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In its June issue, National Geographic magazine has published a selection of startling photos highlighting the vast amounts of discarded plastic choking the world's oceans, shorelines and rivers.

Wildlife, particularly marine animals, are at risk when they become entangled in plastic waste, or ingest it.

Trapped in a plastic bag at a landfill in Spain, this stork has a lucky escape - the photographer later freed it.

One bag can kill more than once: carcasses decay, but the plastic lasts.

Seven charts that explain plastic pollution

Plastic fantastic: How it changed the world

Earth is becoming 'Planet Plastic'

This loggerhead turtle has become entangled in an old plastic fishing net in the Mediterranean, off the coast of Spain.

The turtle could stretch its neck above water to breathe but would have died had the photographer not freed it.

Derelict fishing gear poses a major threat to large marine animals such as turtles.

On Okinawa, Japan, a hermit crab resorts to a plastic bottle cap to protect its soft abdomen.

Beachgoers collect the shells the crabs normally use, leaving their rubbish behind.

The magazine has devoted much of its issue to the problem; the plastic pollution we can see at the surface is probably just a small proportion of what's in the ocean.

Plastic waste can break down into tiny particles, which are less visible, but may still affect marine life.

Plastic 'berg chokes Indonesian river

Plastic heading for oceans quantified

Ocean plastic could triple in decade

'Shame and anger' at plastic pollution

After sheets of clear plastic trash have been washed in the Buriganga River, in Dhaka, Bangladesh, a woman spreads them out to dry.

She turns them regularly, while also tending to her son.

The plastic will eventually be sold to a recycler. Less than one-fifth of all plastic gets recycled globally. In the US it's less than 10%.

These hyenas are shown scavenging at a landfill in Harar, Ethiopia.

They have adapted to the new normal: the animals listen for the collection trucks and find much of their food in the rubbish.

Plastic bottles choke the Cibeles fountain, in central Madrid. An art collective called Luzinterruptus filled this and two other Madrid fountains with 60,000 discarded bottles as a way of calling attention to the environmental impact of disposable plastics.

To ride currents, seahorses clutch drifting seagrass or other natural debris. In the polluted waters off the Indonesian island of Sumbawa, this seahorse has latched onto a plastic cotton bud. Photographer Justin Hofman said it was "a photo I wish didn't exist".
Ellen MacArthur Guest Edits the June issue of National Geographic. Working in collaboration with Global Editor-in-Chief Susan Goldberg and the editorial team, twelve notable British figures, each respected leaders in their fields, have been exploring topics such as sustainability, technology, environmentalism and human ingenuity, as part of this first ever Guest Editor project. It began in January, with the world's greatest living explorer Sir Ranulph Fiennes and a further eight Guest Editors were then announced including Dame Ellen MacArthur, Sir Mo Farah, Lily Cole, Archie Panjabi, Katie Piper, Maria Balshaw and Professor Brian Cox.

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Plastic pollution: Images of a global problem

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In its June issue, National Geographic magazine has published a selection of startling photos highlighting the vast amounts of discarded plastic choking the world's oceans, shorelines and rivers. Wildlife, particularly marine animals, are at risk when they become entangled in plastic waste, or ingest it.

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For indispensable reporting on the coronavirus crisis and more, subscribe to Mother Jones' newsletters.

This story was originally published by the Bulletin of the Atomic Scientists.

On May 24, the Royal Swedish Academy of Sciences will award one of the world's largest scientific prizes to two of the world's top climate researchers. In the presence of Swedish royalty, MIT professor of atmospheric chemistry Susan Solomon and Princeton University senior meteorologist Syukuro Manabe will receive the 2018 Crafoord Prize in Geosciences-and 6 million kronor, equivalent to about $690,000-for "fundamental contributions to understanding the role of atmospheric trace gases in Earth's climate system."

The Crafoord Prize is an annual award established by Swedish industrialist Holger Crafoord and his wife Anna-Greta Crafoord. The Academy is responsible for selecting the Crafoord Laureates, and the prize is awarded in disciplines that complement those for which Nobel Prizes are awarded.

Manabe, one of the founders of climate modeling, did groundbreaking work predicting how the climate system would respond to increases in carbon dioxide. Solomon, who is on the Bulletin's Science and Security Board, is best known for solving the mystery of the ozone hole, the annual thinning of the protective stratospheric ozone layer over Antarctica.

Solomon's studies and measurements in Antarctica identified both the mechanism for ozone destruction and the culprit: chemicals called chlorofluorocarbons, which were once widely used as refrigerants and aerosol propellants. Identifying the problem led to a global solution called the Montreal Protocol, an international treaty to phase out ozone-destroying gases and replace them with less harmful chemicals.

Although Solomon's recent studies have shown that the ozone hole has begun to heal, there is still much to be learned about how the ozone layer is responding to human intervention, and about what can be done to improve its recovery during what Solomon calls the "accountability" period of ozone research. (A group of scientists reported last week that emissions of a banned chemical appear to be rising, which suggests that someone is cheating on the agreement.)

Solomon, who has co-chaired a working group of the Intergovernmental Panel on Climate Change, is also studying how changes in the stratosphere affect Earth's winds and climate systems. Bulletin contributing editor Dawn Stover spoke with her about her work and the Crafoord Prize.

Bulletin of the Atomic Scientists: How did you learn that you'd won the Crafoord Prize? Did you get one of those 5:00 a.m. calls from Stockholm?

Susan Solomon: I was actually on a ship in the middle of the Antarctic Ocean when they called me. There was no telephone, and we had extremely limited Internet, so they sent me an email which I didn't see for a day and a half.

BAS: What were you doing in the Antarctic?

SS: I wish I could tell you that it was a research cruise. I did my real research in the Antarctic in the late '80s and early '90s, and all of our work was out of McMurdo Station, which is on land. But I've on a couple of occasions been a lecturer onboard a tourism ship, and that's what I was doing.

BAS: So you were having fun.

SS: I was doing a little outreach, and talking about how wonderful the Antarctic ecosystem is, and all the great creatures that live down there, and how climate change is affecting some of them. So yeah, it was a lot of fun.

BAS: How many times have you been to Antarctica?

SS: Seven times.

BAS: So you won the prize for solving the mystery of what was causing a hole to appear in the ozone layer. Spoiler alert for our readers: The chlorofluorocarbons did it. For the benefit of people who may not be familiar with your work, can you explain how you figured that out?

SS: Sure. Back in the 1970s people first started wondering whether using chlorofluorocarbons might someday deplete the ozone layer, but we thought that the effect would be a few percent, and it would be far in the future. No one ever expected to see such a big depletion-and in 1985. So it was a tremendous shock when the British Antarctic Survey announced that they'd been measuring ozone since the 1950s; it had spent 20 years being constant and then, boom! It just kind of fell off the map. Nowadays there's only about half as much ozone over your head when you're in the Antarctic in October or November as there would have been in, say, the 1960s. And we knew that similar things were not happening in the Arctic. So if this was caused by chlorofluorocarbon chemistry, it had to be a chemistry operating in a very different way than what we were expecting. And that turned out to be what it is.

BAS: How did you uncover the chemistry?
"If the chlorine from the chlorofluorocarbons was reacting on the surfaces of those stratospheric clouds, that might explain why the Antarctic was so different from the rest of the world."
SS: I started wondering about the fact that Antarctica is the coldest place on Earth, which means that clouds form in the Antarctic stratosphere during the cold season. In the United States, you never see clouds at stratospheric altitudes. You see them in the lower atmosphere, but not up in the stratosphere where the ozone layer exists. And I thought that those clouds might be changing the chemistry in a simple but pretty fundamental way: If the chlorine from the chlorofluorocarbons was reacting on the surfaces of those stratospheric clouds, that might explain why the Antarctic was so different from the rest of the world. I looked at what sorts of reactions might be happening on those surfaces and proposed that particular types of chemistry might be accelerated by those clouds, and that turned out to be right.

BAS: Okay.

SS: I just want to emphasize one thing.

BAS: Sure.

SS: It's not that the clouds themselves are causing the ozone hole. There would be no ozone hole if we hadn't put chlorofluorocarbons in the atmosphere, but the clouds are basically enhancing [the chlorofluorocarbons'] ability to be effective, particularly in the polar regions. We now know that we get some of the same chemistry happening in the Arctic, not to nearly the same degree, but a significant amount of Arctic ozone depletion can also happen, and even over middle latitudes ozone depletion is worse than we expected. So it's an interesting example of an environmental issue where we made some predictions and they turned out to be very conservative, actually. The problem is much more severe than what we thought.

BAS: I think it was the year 2000 that the ozone hole reached its largest size, is that right?

SS: You can actually use all kinds of different ways to define "largest." You could talk about the depth of the ozone hole, in other words, what percent of the ozone that used to be there has been destroyed. If you do that, then you're correct, the deepest ozone holes happened around the year 2000.

BAS: That sounds a bit like the melting of the icecaps; it's not just how much area opens up, but also how thin the ice is.

SS: Exactly.

BAS: It wasn't until 2016, though, that a team that you led identified what I think you said were the first signs of healing of the hole.

SS: That's right.

BAS: Is the ozone layer still at risk, or will the hole keep shrinking from now on?

SS: We have every reason to believe that the ozone hole will recover. It's really quite a remarkable science-policy success story. As I showed in the 2016 paper, if you analyze the data carefully and look at the month of September in particular, you can show that the rate at which the ozone hole opens up every year is getting slower and slower, which is exactly what we expect from the fact that we've stopped putting the chlorofluorocarbons into the atmosphere, but those molecules have very long lifetimes. They live in the atmosphere anywhere between 50 and 100, even 500 years, depending on which one of the molecules you talk about, and there's many different ones that were used in applications like spray cans, solvents, foam blowing, and refrigeration, of course.

Since we stopped emitting them in the late 1990s, what you see today are the leftovers decaying away slowly following a very long lifetime. There will still be ozone holes probably as late as 2050, but probably by the time you get to 2060 or 2070 they won't be happening anymore except maybe once in ten years or something like that; and you might even have a year in the 2030s or 2040s when you might not have an ozone hole. That will be an incredible year. What we showed, which is really exciting, is that, if you account for the kind of variability that is happening and you account for how chlorine has gone away, not only is the rate at which the ozone hole opens up getting slower, but also the area of the ozone hole in September is shrinking and the hole is getting less deep.
"If you account for the kind of variability that is happening and you account for how chlorine has gone away, not only is the rate at which the ozone hole opens up getting slower, but also the area of the ozone hole in September is shrinking."
BAS: That's good news. But a study published recently reported that, although the upper stratospheric layer of ozone appears to be recovering nicely, the ozone in the lower stratosphere is still declining.

SS: Not in the Antarctic. There it's very clear that ozone is beginning to recover. But in the tropics, there's some evidence for ozone losses in the lower stratosphere that are being discussed and debated right now. I think it's too early to say whether that's just interannual variability or whether perhaps the way that the different satellite data steps have been stitched together to produce that result might not be quite right. I think the tropical issue is a new and very interesting science area for the community to explore, but the Antarctic is clearly recovering and it's a very different situation.

BAS: Are you still working on those new studies, or is your ozone work now done?

SS: No, it's not done. I'm having a ball with the recovery. I find the issue of how the ozone hole is displaying its healing process to us to be absolutely fascinating, so I'm having tremendous fun going after that problem, and I have continued to do a whole series of studies on it that look at different pieces of that issue.

BAS: Antarctica is where you started getting the data confirming your theory about the ozone hole. What do you remember most about your time there?

SS: Oh, it was just so wonderful. It is such an incredibly beautiful, awe-inspiring, spectacular place with the most remarkable wildlife that you can imagine, although at McMurdo there's not a lot of that wildlife. When you do see something like a group of emperor penguins, it's really impressive, and whales, and seals, and everything else that's down there, but also just the remoteness of the place. It really is like going to another planet. From a scientific point of view, it was exploration at its best. We had this tremendous mystery, and very few measurements had been made there. If the ozone hole had popped up at another latitude, we would've had a lot more information to go on, but it was just in every way the unexplored last continent.

BAS: After your big breakthrough with the hole, how did you move on from that?

SS: I spent many years, and still do, just doing chemistry of the stratosphere because I find it interesting. I have started doing more work in climate, including this issue of whether changes in wind patterns in the stratosphere actually influence lower altitudes. When we talk about changes in the global climate, nowadays we're looking at warming, relative to 1880, of something like 0.8 degrees Celsius, or on the order of 1.5 degrees Fahrenheit. But when you talk about the stratosphere, the cooling that's occurred due to the ozone hole is just massive. I mean, it's on the order of five degrees per decade over a few decades, so you're talking about 10 degrees, 12 degrees Celsius. The reason for that is that ozone provides the source of heat to the stratosphere. If you take all the ozone away, which is what the ozone hole does, then there's no heat and it just cools like crazy. The potential of that to modify the wind system is very clear, and then to look at how that might propagate into the troposphere all the way down to the ground became something that my colleague, Dave Thompson, and I got interested in, and we did a series of papers, and still are continuing to work on that issue. And it turns out to be pretty important.

BAS: How does that affect the winds?

SS: As the stratosphere has cooled, it's changed the winds in such a way that the troposphere has also cooled over the surface of the continent, and it has strengthened the polar vortex. You often hear how cold weather is caused by the polar vortex here in the United States. The same thing happens in the southern hemisphere to some degree. But in the case of the ozone hole, the polar vortex got even colder and even more stable, and therefore kind of shrunk over the continent. So it made places like the South Pole itself, and the high plateau of East Antarctica, colder than they would have been, and it made the regions just outside the polar vortex warmer-because they're just not getting those excursions of really cold air from higher latitudes anymore, the way they used to. It has also affected rainfall patterns: If you shift the wind patterns, you can shift where the humidity and the rainfall is going. We've shown, and other people have too, that that is actually pretty important for the climates of places like South America, Australia, even parts of Africa. The ozone hole has really rocked the southern hemisphere, as far as climate goes.

BAS: In your work on climate, I imagine that maybe you've had some encounters with climate deniers, but I don't recall ever hearing of any ozone hole deniers. Is there something about the science of climate change that makes it more controversial?
"There were ozone hole deniers, actually, in the very beginning...One of the things that the ozone hole always had going for it was the massiveness of the effect.
SS: There were ozone hole deniers, actually, in the very beginning. There are going to be some people who will distrust the science for whatever reason. As the science gets stronger and clearer, it becomes more and more difficult for that kind of view to be tenable, and I think one of the things that the ozone hole always had going for it was the massiveness of the effect. When you look at ozone measurements from the 1950s and '60s, and you see values that are twice what they are today, it's just a lot easier for people to understand. You don't have to be a statistician to understand a change of a factor of two. But when you talk about climate, I think it's much more different for people to wrap their heads around.

Another thing about the ozone issue is that it was a very clear-cut area as far as what the human impacts would be. If there were to be significant ozone depletion, then it would cause issues like skin cancer and cataracts. Everyone knows that ultraviolet light is bad for you, and if you've ever been sunburned, you know it's not something you want to do too often because it can lead to skin cancer. So the degree of personal concern was universal, whereas when you talk about climate change, I think those of us particularly in the developed world, we feel pretty safe. We have a society that's rich enough to insulate itself against the slings and arrows of climate fortunes. We've got years of bad harvest and years of good harvest, and it doesn't lead to famines in the United States. We just don't feel it as a threat in the same way that we understand skin cancer as a threat. And finally, of course, the solutions to the [ozone] problem were not that difficult to identify. In the case of climate change, a lot of people imagine that's there's no way we could ever get off of fossil fuels. But I think it's been shown, more and more now, how practical many of the solutions actually are. In the case of the ozone issue, the initial problem really had to do with the use of chlorofluorocarbons in spray cans, and a lot of those spray cans were for things like hairspray and deodorant. That was not all that difficult to shift away from, and we still have hairspray; it just doesn't have chlorofluorocarbons in it.

BAS: It is interesting how fixing the problem took a combination of policy (in the form of a global treaty) and a switch to using different products. Would that same combination work for global warming as well?
"What the ozone issue shows you is that it is possible for society to come together and make a decision to regulate a chemical internationally. Every country in the world has signed on to the Montreal Protocol to protect the ozone layer."
SS: I think there is some degree of analogy. What the ozone issue shows you is that it is possible for society to come together and make a decision to regulate a chemical internationally. Every country in the world has signed on to the Montreal Protocol to protect the ozone layer. It's really quite amazing how chemical plants in places like China and India have been closed along with chemical plants in this country. That's a remarkable scientific and policy success story, but it's also dealing with an industry that, all told, is something like only 15 different chemical companies worldwide. I don't know the exact dollar value of the chlorofluorocarbon industry at its height, but it wasn't anything even remotely resembling the fossil fuel industry. Everything we do relies on energy, and as long as energy relies on fossil fuels and it's the engine of our economy and the economies of all other nations too, that makes it difficult for people to contemplate the idea of being part of an international agreement to regulate it.

BAS: Not to mention industry resistance.

SS: I must say, I give the chemical industry some credit. Some of my colleagues argue that they were difficult to deal with in the beginning, and I saw that occasionally, but I also think they were willing to change. The chemical companies are all about innovation. They are always looking for different molecules to make, and I don't think they shrank from the challenge of doing something different.

BAS: How much of that comes down to leadership at the top?

SS: Well, leadership's important, but what's also important is what the nature of the industry actually is. An industry whose nature is to make stuff, I think, honestly, that they're going to be different than an industry whose nature is to extract stuff.

BAS: When you're thinking about the impacts of climate change that are still mostly off in the future, what worries you most about it?

SS: The impact on the developing world. The number of people who will be suffering in countries that contributed very, very little to the problem and just don't have the resources to deal with the impacts. I've done a lot of work recently on issues like the potential effects of climate change on food production in places like Africa, and it's very concerning to me that, as we move into the rest of the 21st century, I think it's going to be very hard to grow food in some parts of Africa. Again, we're insulated because we're rich enough to afford things like irrigation. A fair amount of Africa doesn't have that, so they are completely reliant on what falls from the sky as rain. If that's changing, or if it's hotter and there's more evaporation, what's that doing to them? Certainly ecosystems and agriculture, as well as human health, are at risk. People die from heat waves. People died last year in India, if you remember.

BAS: You got my attention with a paper that you edited last year that talked about the risk of a planet so hot that literally billions of people could die without air conditioning.

SS: Beyond a certain temperature, the human body is unable to cool itself if the relative humidity is too high.

BAS: So you can't live in that place anymore?

SS: Well, you can only live in that place if you're living in a bubble, right? I mean, kids can't go outside to play. You'll have to be in air conditioning essentially all the time. Maybe you can quickly go from your vehicle to your air-conditioned store or home or whatever, but you're going to be living in a surreal kind of world.

BAS: You've been on a lot of advisory panels, including here on the Bulletin 's own Science and Security Board, and you're very well-known as a scientist. You get inquiries from journalists like me all the time, and I'm wondering how you balance your public life as an ambassador for science with your professional and private life as somebody who is still actively doing research.

SS: I view it as a responsibility to do some public outreach, and I'm particularly aware of the fact that there's a fair number of younger, early-career women in this field, but I started out at a time when women were extremely few and far between. Because of that, I put effort into activities that I think help with the role-model aspect. I still have to limit it. Sometimes I have to decide, "No, I can't do that because I just don't have time and it would take too much time away from the research that I love."

BAS: In another interview, you talked some about the dangers of scientists becoming too sure of themselves as they get older, and the importance of examining your own thinking and staying open to completely new ideas. In the context of climate change, how do you advocate for that kind of "uncertainty" without playing into the hands of people who are promoting uncertainty as a reason to do nothing about global warming?

SS: Well, don't ever forget that uncertainties cut both ways. It's also quite possible to underestimate how bad things could be, and we certainly did that with the ozone problem. Climate is all about risk. There's a risk that we're going to be over-careful, I suppose, in doing things to protect ourselves from climate change. But there's a much bigger risk that we're going to be under-careful and not do enough. We don't buy fire insurance for our homes because we think the home is going to burn; we buy it because of how bad it would be if it actually did. In this case, we know that our home is going to get a lot hotter, and it could happen faster than we think. I see so many indicators that a lot of things are going to be bad.

An easy example is wildfire: We're seeing more and more of it, and the fire season is now longer than it used to be. We don't really understand ecosystem dynamics well enough to fully predict how bad it could get, but I think we have every reason to believe that it's going to be just horrible. There will be places where the landscape will be permanently altered. I find that sort of thing to be heart-wrenching, because of what it's going to do to the people who live in those places.

BAS: You seem to really love a challenge, so what is the encore to solving the ozone puzzle?

SS: I think we are in an interesting phase now with ozone that some people call the accountability period. The first period of ozone research sometimes is called credibility: Was [the ozone hole] real? Then we moved into manageability: What can we do about it? Now we're into accountability: Have we done all the things we could do? There are still, for example, chlorofluorocarbons out there in what's sometimes called the banks, things like old refrigerators and old air conditioners. To what extent is our recycling process operating at top efficiency, to better recover all that material that we don't need anymore? I think that's a very, very interesting question. And then, just understanding the chemistry of how the ozone layer responds as chlorine decreases is a fascinating and interesting problem, too. I'm not bored with ozone yet.

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Some actual good news about the ozone layer

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For indispensable reporting on the coronavirus crisis and more, subscribe to Mother Jones' newsletters. This story was originally published by the Bulletin of the Atomic Scientists. On May 24, the Royal Swedish Academy of Sciences will award one of the world's largest scientific prizes to two of the world's top climate researchers.

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As the world seeks to slow the pace of climate change, preserve wildlife, and support more than eight billion people, trees inevitably hold a major part of the answer. Yet the mass destruction of trees-deforestation-continues, sacrificing the long-term benefits of standing trees for short-term gain of fuel, and materials for manufacturing and construction.

We need trees for a variety of reasons, not least of which is that they absorb the carbon dioxide we exhale and the heat-trapping greenhouse gases that human activities emit. As those gases enter the atmosphere, global warming increases, a trend scientists now prefer to call climate change.

There is also the imminent danger of disease caused by deforestation. An estimated 60 percent of emerging infectious diseases come from animals, and a major cause of viruses' jump from wildlife to humans is habitat loss, often through deforestation.

But we can still save our forests. Aggressive efforts to rewild and reforest are already showing success. Tropical tree cover alone can provide 23 percent of the climate mitigation needed to meet goals set in the Paris Agreement in 2015, according to one estimate.

Causes of deforestation

Forests still cover about 30 percent of the world's land area, but they are disappearing at an alarming rate. Since 1990, the world has lost more than 420 million hectares or about a billion acres of forest, according to the Food and Agriculture Organization of the United Nations-mainly in Africa and South America. About 17 percent of the Amazonian rainforest has been destroyed over the past 50 years, and losses recently have been on the rise. The organization Amazon Conservation reports that destruction rose by 21 percent in 2020, a loss the size of Israel.

Farming, grazing of livestock, mining, and drilling combined account for more than half of all deforestation. Forestry practices, wildfires and, in small part, urbanization account for the rest. In Malaysia and Indonesia, forests are cut down to make way for producing palm oil, which can be found in everything from shampoo to saltine crackers. In the Amazon, cattle ranching and farms-particularly soy plantations-are key culprits.

Logging operations, which provide the world's wood and paper products, also fell countless trees each year. Loggers, some of them acting illegally, also build roads to access more and more remote forests-which leads to further deforestation. Forests are also cut as a result of growing urban sprawl as land is developed for homes.

Not all deforestation is intentional. Some is caused by a combination of human and natural factors like wildfires and overgrazing, which may prevent the growth of young trees.

Why it matters

There are some 250 million people who live in forest and savannah areas and depend on them for subsistence and income-many of them among the world's rural poor.

Eighty percent of Earth's land animals and plants live in forests, and deforestation threatens species including the orangutan, Sumatran tiger, and many species of birds. Removing trees deprives the forest of portions of its canopy, which blocks the sun's rays during the day and retains heat at night. That disruption leads to more extreme temperature swings that can be harmful to plants and animals.

With wild habitats destroyed and human life ever expanding, the line between animal and human areas blurs, opening the door to zoonotic diseases. In 2014, for example, the Ebola virus killed over 11,000 people in West Africa after fruit bats transmitted the disease to a toddler who was playing near trees where bats were roosting.

(How deforestation is leading to more infectious diseases in humans.)

Some scientists believe there could be as many as 1.7 million currently "undiscovered" viruses in mammals and birds, of which up to 827,000 could have the ability to infect people, according to a 2018 study.

Deforestation's effects reach far beyond the people and animals where trees are cut. The South American rainforest, for example, influences regional and perhaps even global water cycles, and it's key to the water supply in Brazilian cities and neighboring countries. The Amazon actually helps furnish water to some of the soy farmers and beef ranchers who are clearing the forest. The loss of clean water and biodiversity from all forests could have many other effects we can't foresee, touching even your morning cup of coffee.

In terms of climate change, cutting trees both adds carbon dioxide to the air and removes the ability to absorb existing carbon dioxide. If tropical deforestation were a country, according to the World Resources Institute, it would rank third in carbon dioxide-equivalent emissions, behind China and the U.S.

What can be done

The numbers are grim, but many conservationists see reasons for hope. A movement is under way to preserve existing forest ecosystems and restore lost tree cover by first reforesting (replanting trees) and ultimately rewilding (a more comprehensive mission to restore entire ecosystems).

(Which nation could be the first to be rewilded?)

Organizations and activists are working to fight illegal mining and logging-National Geographic Explorer Topher White, for example, has come up with a way to use recycled cell phones to monitor for chainsaws. In Tanzania, the residents of Kokota have planted more than 2 million trees on their small island over a decade, aiming to repair previous damage. And in Brazil, conservationists are rallying in the face of ominous signals that the government may roll back forest protections.

(Which tree planting projects should you support?)

Stopping deforestation before it reaches a critical point will play a key role in avoiding the next zoonotic pandemic. A November 2022 study showed that when bats struggle to find suitable habitat, they travel closer to human communities where diseases are more likely to spillover. Inversely, when bats' native habitats were left intact, they stayed away from humans. This research is the first to show how we can predict and avoid spillovers through monitoring and maintaining wildlife habitats.

For consumers, it makes sense to examine the products and meats you buy, looking for sustainably produced sources when you can. Nonprofit groups such as the Forest Stewardship Council and the Rainforest Alliance certify products they consider sustainable, while the World Wildlife Fund has a palm oil scorecard for consumer brands.

Editor's note: This story was originally published on February 2019. It has been updated.

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Deforestation and Its Effect on the Planet

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Large scale destruction of trees-deforestation-affects ecosystems, climate, and even increases risk for zoonotic diseases spreading to humans.

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What are genetically modified organisms (GMOs)?

Genetically modified organisms (or GMOs, for short) are any plant, animal, or bacteria that has been altered at the genetic level in a laboratory. These organisms do not occur naturally. Genetic scientists can take genes from one organism and add them to another, or they can remove genetic material to get rid of undesired traits.

Creating GMOs

Genetically modified organisms are created for a variety of applications. Scientists have created crops that are more resistant to weather, pests, and chemicals, all while providing higher yields. They're also working toward increasing the nutritional content of food, especially for foods sent to impoverished nations. For example, a new type of rice called golden rice is being developed to supply nutrition-poor areas with a reliable source of vitamin A.

GMOs are also used to make a variety of biofuels like corn-derived ethanol and algae biodiesel, as well as numerous medical products like growth hormones and insulin.

Genetically modified animals also exist. Examples include goats that create spider silk proteins in their milk, fish that glow in the dark under ultraviolet light, and sheep that glow green.

Notable uses of GMOs

GMOs were once used to prevent the destruction of an entire industry. In the 1990s, the Hawaiian papaya was saved from a devastating virus, thanks to the creation of a genetically modified papaya that was resistant to the virus.

Scientists have also modified animals to combat disease. In 2014, Brazil authorized the release of genetically modified mosquitoes into the wild to combat Dengue fever, which is spread by mosquitoes. By 2016, it was confirmed that the occurrence of Dengue fever had fallen by 91 percent in areas where the modified mosquitoes had been released.

GMO safety

In 2016, the National Academy of Sciences released a study showing that no one has gotten sick due to consuming food with genetically modified ingredients. However, many people around the world remain skeptical. Due to this skepticism, many nations have restricted or banned the growth and sale of GMOs.

Despite the uncertainty, genetically modified foods have become common in the United States. Most of the corn, soybeans, and sugar beets used to produce packaged food is genetically modified in some way. It's also been possible to purchase modified meat since late 2015, when genetically modified salmon was approved for sale. Thus far, no health problems have been reported.

With respect to the environment, however, genetically modified crops have caused problems. By making the crops more resistant to chemicals and pests, both weeds and pests have adapted, forcing the use of stronger pesticides and modified crops to keep everything under control.

Avoiding GMO foods

If you are uncomfortable eating food with genetically modified ingredients, try eating organic. Organic food producers are prohibited from using any GMOs in the cultivation of their products.

In most countries, you can also check the labels on your food for genetically modified contents. Here's an example of a U.S. Nutrition Facts label for food containing genetically modified ingredients. Note that it says Genetic Engineering, which is another term for manipulating the genes of an organism in a lab.

The debate on GMOs

Some critics are concerned that the companies creating modified crops control too much of the agricultural process. These critics don't want a nation's agricultural industry to be dependent on this handful of companies, especially because many farmers in poorer nations have no choice but to rely on these companies.

Further disagreement stems from the actual effectiveness of modified crops. For instance, while the United States has grown modified crops since the mid-1990s, Europe has avoided them. According to The New York Times, Europe's non-modified corn yields have increased at the same rate as American yields over the past 20 years. These findings go against industry claims that modified crops generate larger yields.

At the same time, many agricultural experts claim that modified crops are worthwhile and have changed their lives for the better. Their findings state that modified crops require less pesticide and oversight, thus saving farmers time and money.

The controversy over genetically modified organisms will likely continue for years to come. Even as the science behind GMOs shows that they're safe and effective, GMO opponents will argue that many problems remain with the technology. Only time will tell if GMOs will eventually be accepted by the public at large.

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The Now: What are Genetically Modified Organisms (GMOs)?

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en/thenow/what-is-3d-printing/content/ Genetically modified organisms (or GMOs, for short) are any plant, animal, or bacteria that has been altered at the genetic level in a laboratory. These organisms do not occur naturally. Genetic scientists can take genes from one organism and add them to another, or they can remove genetic material to get rid of undesired traits.

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"Invasive species"-they may not sound very threatening, but these invaders, large and small, have devastating effects on wildlife.

Invasive species are among the leading threats to native wildlife. Approximately 42 percent of threatened or endangered species are at risk due to invasive species.

Human health and economies are also at risk from invasive species. The impacts of invasive species on our natural ecosystems and economy cost billions of dollars each year. Many of our commercial, agricultural, and recreational activities depend on healthy native ecosystems.

What Makes a Species "Invasive"?

An invasive species can be any kind of living organism-an amphibian (like the cane toad), plant, insect, fish, fungus, bacteria, or even an organism's seeds or eggs-that is not native to an ecosystem and causes harm. They can harm the environment, the economy, or even human health. Species that grow and reproduce quickly, and spread aggressively, with potential to cause harm, are given the label "invasive."

An invasive species does not have to come from another country. For example, lake trout are native to the Great Lakes, but are considered to be an invasive species in Yellowstone Lake in Wyoming because they compete with native cutthroat trout for habitat.

How Invasive Species Spread

Invasive species are primarily spread by human activities, often unintentionally. People, and the goods we use, travel around the world very quickly, and they often carry uninvited species with them. Ships can carry aquatic organisms in theirballast water, while smaller boats may carry them on their propellers. Insects can get into wood, shipping palettes, and crates that are shipped around the world. Some ornamental plants can escape into the wild and become invasive. And some invasive species are intentionally or accidentally released pets. For example, Burmese pythons are becoming a big problem in the Everglades.

In addition, higher average temperatures and changes in rain and snow patterns caused by climate change will enable some invasive plant species-such as garlic mustard, kudzu, and purple loosestrife-to move into new areas. Insect pest infestations will be more severe as pests such as mountain pine beetle are able to take advantage of drought-weakened plants.

Threats to Native Wildlife

Invasive species cause harm to wildlife in many ways. When a new and aggressive species is introduced into an ecosystem, it may not have any natural predators or controls. It can breed and spread quickly, taking over an area. Native wildlife may not have evolved defenses against the invader, or they may not be able to compete with a species that has no predators.

The direct threats of invasive species include preying on native species, outcompeting native species for food or other resources, causing or carrying disease, and preventing native species from reproducing or killing a native species' young.

There are indirect threats of invasive species as well. Invasive species can change the food web in an ecosystem by destroying or replacing native food sources. The invasive species may provide little to no food value for wildlife. Invasive species can also alter the abundance or diversity of species that are important habitat for native wildlife. Aggressive plant species like kudzu can quickly replace a diverse ecosystem with a monoculture of just kudzu. Additionally, some invasive species are capable of changing the conditions in an ecosystem, such as changing soil chemistry or the intensity of wildfires.

Examples of Invasive Species

Cogongrass is an Asian plant that arrived in the United States as seeds in packing material. It is now spreading through the Southeast, displacing native plants. It provides no food value for native wildlife, and increases the threat of wildfire as it burns hotter and faster than native grasses.

Feral pigs will eat almost anything, including native birds. They compete with native wildlife for food sources such as acorns. Feral pigs spread diseases, such as brucellosis, to people and livestock. E. coli from their feces was implicated in the E. coli contamination of baby spinach in 2006.

European green crabs found their way into the San Francisco Bay area in 1989. They outcompete native species for food and habitat and eat huge quantities of native shellfish, threatening commercial fisheries.

Dutch elm disease (caused by the fungus Ophiostoma ulmi) is transmitted to trees by elm bark beetles. Since 1930, the disease has spread from Ohio through most of the country, killing over half of the elm trees in the northern United States.

Water hyacinth is a beautiful aquatic plant, introduced to the U.S. from South America as an ornamental. In the wild, it forms dense mats, reducing sunlight for submerged plants and aquatic organisms, crowding out native aquatic plants, and clogging waterways and intake pipes.

Curbing the Spread

One way to curb the spread of invasive species is to plant native plants and remove any invasive plants in your garden. There are many good native plant alternatives to common exotic ornamental plants. In addition, learn to identify invasive species in your area, and report any sightings to your county extension agent or local land manager.

Regularly clean your boots, gear, boat, tires, and any other equipment you use outdoors to remove insects and plant parts that may spread invasive species to new places. When camping, buy firewood near your campsite (within 30 miles) instead of bringing your own from home, and leave any extra for the next campers. Invertebrates and plants can easily hitch a ride on firewood you haul to or from a campsite-you could inadvertently introduce an invasive to a new area.

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Invasive Species | National Wildlife Federation

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Invasive species are among the leading threats to native wildlife. Learn about how they spread and how they threaten native wildlife in the United States.

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The page you tried was not found. You may have used an outdated link or may have typed the address (URL) incorrectly. You might find what you're looking for in one of these areas:

For Technical Support, visit the MH Education Support site at www.mhhe.com/support.

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The page you tried was not found. You may have used an outdated link or may have typed the address (URL) incorrectly. You might find what you're looking for in one of these areas: For Technical Support, visit the MH Education Support site at www.mhhe.com/support.

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Whale Poaching: 122 Pregnant whales killed:(

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Whale Poaching: 122 Pregnant whales killed:(

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Japanese hunters caught and killed 122 pregnant minke whales as part of its Antarctic summer "field survey".

A report sent to the International Whaling Commission (IWC) reveals hunters caught 333 minkes in total.

The team left Japan in November 2017 for the Southern Ocean and returned in March 2018.

Japan says its whaling programme is for scientific purposes, despite a 2014 UN ruling against its "lethal research" and widespread condemnation.

In a new research plan published after the UN ruling, Japan said it was "scientifically imperative" to understand Antarctica's ecosystem through collecting and analysing animals.

Japan to resume whaling in Antarctic

Why Japan keeps on whaling

Is Japan losing the taste for whale meat?

How many whales did Japan catch?

The country's New Scientific Whale Research Program in the Antarctic Ocean (NEWREP-A) sent a report to the IWC detailing the 333 minkes caught, 152 male and 181 female, during its "third biological field survey" in the area.

Japan cut down its catch by two-thirds under its new research plan, and has stuck to taking about 330 whales each year.

The data shows that in the 2017/18 hunt, 122 of the female minkes captured were pregnant, while 61 of the males and 53 of the females were not yet adults.

After a few weeks of surveys, the team caught all the whales within just 12 weeks before setting off back to Japan.

The whale meat is then sold to be eaten.

Why does Japan hunt whales?

Under Article VIII of the International Convention for the Regulation of Whaling, signed in 1946, countries can "kill, take and treat whales for purposes of scientific research", and this is the rule Japan says it follows in its hunts.

Aside from its research claims, the Japanese government says whale hunting is an ancient part of Japan's culture.

Coastal communities in Chiba prefecture and Ishinomaki in northern Japan have long practised coastal whaling, while Taiji in Wakayama prefecture holds annual dolphin hunts.

However, expeditions to the Antarctic for whale meat only began after World War Two, when the devastated country depended on whales as its main source of meat.

While the meat is still sold, it is increasingly unpopular, with far fewer businesses selling it now than in the past.

Does anyone else hunt whales?

Figures from charity Whale and Dolphin Conservation (WDC) show that many countries other than Japan still catch whales.

The International Whaling Commission (IWC), which regulates the industry, agreed to a moratorium on commercial whaling from the 1985, with exceptions.

Norway and Iceland still hunt whales for meat, the former rejecting the moratorium and the latter only partially agreeing.

So-called aboriginal subsistence whaling for local communities continues in Greenland, Russia, the USA, and St Vincent and the Grenadines.

But Japan remains the only country to send ships to Antarctica to catch whales, under the scientific research exemption.

Is the hunting wiping out Antarctic whales?

Japan says it is conducting its research to show the Antarctic whale population is healthy and can be sustainably fished.

The International Union for Conservation of Nature (IUCN) says there is insufficient data to determine whether the Antarctic minke whale is threatened.

While the number of minkes is "clearly in the hundreds of thousands", they are investigating a possible decline over the last 50 years.

Depending on how significant the drop is, the Antarctic minke could be classified as Least Concern, or as Endangered.

You may also be interested in:

A guide to the great whales

Beached whales die en masse in Australia

The people of the whale

Killer whale could be saying 'set me free'

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Japanese hunters kill 122 pregnant whales

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Japanese hunters caught and killed 122 pregnant minke whales as part of its Antarctic summer "field survey". A report sent to the International Whaling Commission (IWC) reveals hunters caught 333 minkes in total. The team left Japan in November 2017 for the Southern Ocean and returned in March 2018.

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https://www.awf.org/campaigns/lion-poaching/

https://news.nationalgeographic.com/2017/10/wildlife-watch-poachers-south-africa-target-captive-lions/#close

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It was a fairy tale ending when 33 lions rescued from circuses in Peru and Colombia were airlifted to a sanctuary in South Africa in May 2016. Setting foot on the sandy soil after years of abuse, they must have felt they were in paradise.

Right from the start, two of the male lions, José and Liso, housed in the special needs section of the Emoya Big Cat Sanctuary, were fast friends. Liso looked out for José, who had brain damage from blows to his head during his circus days, guiding him around their enclosure.

When the team from Animal Defenders International first saw them in Peru, "they were snarling, spitting balls of fury," recalls Jan Creamer, CEO and co-founder of the London-based nonprofit. But with reassuring routines and gentle treatment in their new home, the lions soon calmed down.

Then in the early hours of May 29, 2017, tragedy struck: Poachers entered the sanctuary, poisoned José and Liso in their enclosure, and hacked off their heads, tails, paws, and skins.

The killing appears to be the leading edge of a new trend: poachers targeting lions at sanctuaries, private nature reserves, and breeding farms for their body parts.

Lion bones are sought after in Asia for use in traditional medicine-as health tonics and wines-and increasingly as a substitute for remedies made from the bones of tigers, whose numbers in the wild are somewhere around 3,900. Lion teeth and claws are also in high demand in China and elsewhere in Asia as necklaces and other adornments and trinkets. In some African countries the heads, tails, and paws are favored for use in traditional medicine, known as muti.

"It really shook us," says Tim Phillips, co-founder of Animal Defenders with Creamer, of José and Liso's killing. "We lived with them for a long time. We did a lot of one-on-one rehabilitation with them, and we did a lot to get them. We were so close to these animals. They were favorites."

He says the top priority now is to find José and Liso's killers. "They've picked on the worst people possible. They've killed two members of the ADI family, and we will not let it go."

WHO'S BEHIND THE KILLINGS?

Animal Defenders International is working with police in South Africa and also gathering information about other attacks on privately owned captive lions. In 2015 there were none. "Then in 2016 the attacks began and have continued to escalate," Phillips says. "It's part of an awful pattern."

According to Animal Defenders, at least 20 captive lions, including José and Liso, were killed or targeted in Limpopo province, in the northeastern part of the country, during the first eight months of 2017. The trend is upward-during all of 2016, 18 attacks were reported. Most victims were poisoned and mutilated, with their heads, paws, and other parts cut off.

Paul Funston, senior director of the lion program at Panthera, a conservation organization devoted to the world's wild cats, says there's also been "a massive spike" in killings of lions in the wild during the past few years. "Poachers cut off the head and feet and leave the mutilated carcass. They extract the teeth and claws later. It's much rarer for poachers to process the lion for bones because it takes longer."

Funston suggests that some of the same people involved in lion killings may also be poaching rhinos-lion parts, which may be legal, are sometimes found in shipments of smuggled rhino horns. When Mozambican authorities seized 23 rhino horns at Maputo airport in March 2016, for example, they also found 19 lion teeth and 57 claws. The arrest in May 2017 of a rhino horn kingpin in Vietnam also yielded lion parts. In South Africa seven suspects were arrested in February 2017 for smuggling rhino horn, elephant ivory, and lion claws and teeth, and a bust in June uncovered a stash of rhino horns and lion bones.

Phillips believes the legal international trade in bones and other parts from captive-bred lions is contributing to the killings by stoking demand. The decision to keep a legal trade in the parts of captive lions was a compromise made at the meeting in South Africa last year of 182 countries that are party to the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES). A proposal to stop all commercial trade in lions and their parts was rejected, and it was instead decided to prohibit international commercial trade in bones, teeth, and claws from wild lions and continue allowing it for captive-bred lions.

In the past, says Panthera's Funston, conservationists didn't think that trade in lion parts was a serious threat. More problematic, it was believed, were habitat loss, bush meat hunting of lions' prey animals, which robs the cats of food, conflict with humans over lions' predation of their livestock, and trophy hunting.

Between 2008 and 2011 South Africa legally exported 1,160 captive lion skeletons (almost 11 tons), and in June it announced a quota of 800 skeletons for 2017.

Sales in Asia of bones, teeth, and claws are booming, and Funston thinks that's partly because the legal trade has stimulated new markets. "In the past there was tiger bone wine," he says. "Now you can buy lion bone wine-it's a completely new product."

Colman O'Criodain, the World Wildlife Fund's wildlife practice policy manager, is of like mind. He told the Guardian that, "as with the trade of parts of captive-bred tigers, the trade in bone from captive-bred lion keeps demand for big cat bone alive and complicates enforcement efforts."

According to Funston, increased demand in Africa for traditional medicine products isn't to blame. "There's always been a demand for lion parts for muti," he says. "What's changed? I can see no trigger or driver for why there would be an upsurge. This is 100 percent driven by new demand in the Far East."

Michael 't Sas-Rolfes, a research fellow with the Oxford Martin Programme on the Illegal Wildlife Trade and a lead researcher for a forthcoming report on the lion bone trade, notes that certain bones in a lion's paw are used by Africans in the traditional practice of "throwing the bones" to divine information about such things as personal difficulties and health problems. He acknowledges that although José and Liso may have been killed not for their bones but for muti, Asian demand for bones may be playing a role in the increased killings of privately owned lions.

Even if captive lion killings aren't directly related to the Asian market, they may be indirectly influenced by it, according to 't Sas-Rolfes. In South Africa, he says, "lion hunting had been going on for some time, providing a low-cost source of body parts to the locals." But now that lion carcasses "have acquired greater value for the export market, the supply to the local market is likely not as secure or cheap as it was, and that might be a factor that's contributing to local poaching for muti."

He also notes that lion ranchers in South Africa were thrown into disarray by the U.S. Fish and Wildlife Service's ban, as of October 2016, on imports of trophies from captive-bred lions because " canned" hunting of these cats was determined to have no conservation value. "A lot of breeders have lost one of their most significant markets," 't Sas-Rolfes says, and that means some may be stepping up their breeding for lion bones. "It's not a stable industry right now."

Although it's not possible to draw a direct line between the CITES decision and our lions dying, Phillips says, "it's part of the same tapestry." All the markets for lion parts-from traditional medicine to trophies-are a mixture of legal and illegal, he says. Captive lions are easy prey, and "until we have more comprehensive protection and make it incredibly hard to sell any of these animals' body parts, these killings will continue."

"It is important not to react on the basis of assumptions or rumors, especially given the emotive nature of some of these issues," notes CITES spokesman Yuan Liu. "As a science and facts-based convention, CITES will analyze and consider the available data before drawing conclusions as a part of its science-based decision making."

CITES, he says, is undertaking a study due in July 2018 on the legal and illegal trade in lions, including lion bones and other parts and derivatives, to ascertain, among other things, the origin and smuggling routes of that trade. "Only when this study is completed will [CITES] be in a position to meaningfully comment."

Protecting the 31 remaining lions rescued by Animals Defenders International that live at the Emoya sanctuary is expensive-"a huge, sudden add-on," Jan Creamer says. The organization is now spending $7,000 a month on armed guards, plus more for other needed security improvements.

To help defray these costs, Animal Defenders, together with the musician Moby, launched the José and Liso Anti-Poaching Fund. The fund, which has an initial target of $100,000, will support the South African police's anti-poaching officers with their investigations, help collect and analyze information, and identify poaching patterns in order to bring José and Liso's killers to justice. It will also be used to investigate and obtain evidence on other killings of captive lions and other big cats and to build a picture of what is happening and where.

Phillips hopes that what befell the two lions will help end the lion parts trade before it reaches the terrible scale of the tiger trade. José and Liso, Phillips says, "lived together, looked after each other, and-tragically-died together."

Read more stories about wildlife crime and exploitation on National Geographic's Wildlife Watch. Send tips, feedback, and story ideas tongwildlife@natgeo.com.

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Poachers Target Rescued Circus Lions in Worrying New Trend

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It was a fairy tale ending when 33 lions rescued from circuses in Peru and Colombia were airlifted to a sanctuary in South Africa in May 2016. Setting foot on the sandy soil after years of abuse, they must have felt they were in paradise.

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published on 3 November 2016 in water

What is eutrophication? Causes, effects and control

After seeing the picture of children swimming in a sea of seaweed, you will surely wonder what strange phenomenon has hit the coast of Qingdao in eastern China. It is an abnormal growth of algae, a clear manifestation of a process called eutrophication.
" Eutrophication is an enrichment of water by nutrient salts that causes structural changes to the ecosystem such as: increased production of algae and aquatic plants, depletion of fish species, general deterioration of water quality and other effects that reduce and preclude use". This is one of the first definitions given to the eutrophic process by the OECD (Organization for Economic Cooperation and Development) in the 70s.
Eutrophication is a serious environmental problem since it results in a deterioration of water quality and is one of the major impediments to achieving the quality objectives established by the Water Framework Directive (2000/60/EC) at the European level. According to the Survey of the State of the World's Lakes, a project promoted by the International Lake Environment Committee, eutrophication affects 54% of Asian lakes, 53% of those in Europe, 48% of those in North America, 41% of those in South America and 28% of those in Africa ( www.lescienze.it).
All water bodies are subject to a natural and slow eutrophication process, which in recent decades has undergone a very rapid progression due to the presence of man and his activities (so called cultural eutrophication).
The cultural eutrophication process consists of a continuous increase in the contribution of nutrients, mainly nitrogen and phosphorus (organic load) until it exceeds the capacity of the water body (i.e. the capacity of a lake, river or sea to purify itself) , triggering structural changes in the waters.
These structural changes mainly depend on 3 factors:

Use of fertilisers: Agricultural practices and the use of fertilisers in the soil contribute to the accumulation of nutrients. When these nutrients reach high concentration levels and the ground is no longer able to assimilate them, they are carried by rain into rivers and groundwater that flow into lakes or seas.

Discharge of waste water into water bodies: In various parts of the world, and particularly in developing countries, waste water is discharged directly into water bodies such as rivers, lakes and seas. The result of this is the release of a high quantity of nutrients which stimulates the disproportionate growth of algae. In industrialised countries, on the other hand, waste water can be illegally discharged directly into water bodies. When instead water is treated by means of water treatment plants before discharge into the environment, the treatments applied are not always such as to reduce the organic load, with the consequent accumulation of nutrients in the ecosystem.

Reduction of self purification capacity: Over the years, lakes accumulate large quantities of solid material transported by the water (sediments). These sediments are such as to able to absorb large amounts of nutrients and pollutants. Consequently, the accumulation of sediments starts to fill the basin and, increasing the interactions between water and sediment, the resuspension of nutrients present at the bottom of the basin is facilitated (N. Sechi, 1986). This phenomenon could in fact lead to a further deterioration of water quality, accentuating the processes connected with eutrophication (V. Tonolli, 2001).

Formation mechanism
By clicking here you can see a short outreach video that well describes the eutrophication process. Eutrophication is characterised by a significant increase of algae (microscopic organisms similar to plants) due to the greater availability of one or more growth factors necessary for photosynthesis, such as sunlight, carbon dioxide and nutrients (nitrogen and phosphorus). When algae start to grow in an uncontrolled manner, an increasingly large biomass is formed which is destined to degrade. In deep water, a large amount of organic substance accumulates, represented by the algae having reached the end of their life cycle. To destroy all the dead algae, an excessive consumption of oxygen is required, in some cases almost total, by microorganisms. An anoxic (oxygen-free) environment is thus created on the lake bottom, with the growth of organisms capable of living in the absence of oxygen (anaerobic), responsible for the degradation of the biomass. The microorganisms, decomposing the organic substance in the absence of oxygen, free compounds that are toxic, such as ammonia and hydrogen sulphide (H ₂ S). The absence of oxygen reduces biodiversity causing, in certain cases, even the death of animal and plant species. All this happens when the rate of degradation of the algae by microorganisms is greater than that of oxygen regeneration, which in summer is already present in low concentrations.

Effects
The disturbance of aquatic equilibria may be more or less evident according to the enrichment of water by nutrients (phosphorus and nitrogen). An aquatic environment with a limited availability of phosphorus and nitrogen is described as "oligotrophic" while one with high availability of these elements is called "eutrophic"; a lake with intermediate availability is called "mesotrophic".When the eutrophication phenomenon becomes particularly intense, undesirable effects and environmental imbalances are generated. The two most acute phenomena of eutrophication are hypoxia in the deep part of the lake (or lack of oxygen) and algal blooms that produce harmful toxins, processes that can destroy aquatic life in the affected areas ( www.unep.or.jp).
The main effects caused by eutrophication can be summarised as follows (N. Sechi, 1986):

abundance of particulate substances (phytoplankton, zooplankton, bacteria, fungi and debris) that determine the turbidity and colouration of the water;

abundance of inorganic chemicals such ammonia, nitrites, hydrogen sulphide etc. that in the drinking water treatment plants induce the formation of harmful substances such as nitrosamines suspected of mutagenicity;

abundance of organic substances that give the water disagreeable odours or tastes, barely masked by chlorination in the case of drinking water. These substances, moreover, form complex chemical compounds that prevent normal purification processes and are deposited on the walls of the water purifier inlet tubes, accelerating corrosion and limiting the flow rate;

the water acquires disagreeable odours or tastes (of earth, of rotten fish, of cloves, of watermelon, etc.) due to the presence of particular algae;

disappearance or significant reduction of quality fish with very negative effects on fishing (instead of quality species such as trout undesirable ones such as carp become established);

possible affirmation of toxic algae with potential damage to the population and animals drinking the affected water;

prohibition of touristic use of the lake and bathing, due to both the foul odour on the shores caused by the presence of certain algae, as well as the turbidity and anything but clean and attractive appearance of the water; bathing is dangerous because certain algae cause skin irritation;

reduction of oxygen concentration, especially in the deeper layers of the lake at the end of summer and in autumn.

In the light of these significant repercussions and serious consequent economic and naturalistic damage, there is a clear need to curb the progress of eutrophication, avoiding the collapse of the affected ecosystems.

Control
In the past, the traditional eutrophication reduction strategies, including the alteration of excess nutrients, physical mixing of the water, application of powerful herbicides and algaecides, have proven ineffective, expensive and impractical for large ecosystems (Michael F. Chislock, 2013). Today, the main control mechanism of the eutrophic process is based on prevention techniques, namely removal of the nutrients that are introduced into water bodies from the water.It would be sufficient to reduce the concentrations of one of the two main nutrients (nitrogen and phosphorus), in particular phosphorus which is considered to be the limiting factor for the growth of algae, acting on localised loads (loads associated with waste water) and widespread loads (phosphorus loads determined by diffuse sources such as land and rain). The load is the quantity (milligrams, kilograms, tons, etc.) of nutrients introduced into the environment due to human activity.
The possible activities to be undertaken to prevent the introduction of nutrients and to limit phosphorus loads can be summarised as follows ( www3.uninsubria.it):

improvement of the purifying performance of waste water treatment plants, installing tertiary treatment systems to reduce nutrient concentrations;

implementation of effective filter ecosystems to remove nitrogen and phosphorus present in the run-off water (such as phyto-purification plants);

reduction of phosphorous in detergents;

rationalisation of agricultural techniques through proper planning of fertilisation and use of slow release fertilisers;

use of alternative practices in animal husbandry to limit the production of waste water.

In cases where water quality is already so compromised as to render any preventive initiative ineffective, "curative" procedures can be implemented, such as:

removal and treatment of hypolimnetic water (deep water in contact with the sediments) rich in nutrients since in direct contact with the release source;

drainage of the first 10-20 cm of sediment subject to biological reactions and with high phosphorus concentrations;

oxygenation of water for restore the ecological conditions, reducing the negative effects of the eutrophic process, such as scarcity of oxygen and formation of toxic compounds deriving from the anaerobic metabolism;

chemical precipitation of phosphorous by the addition of iron or aluminium salts or calcium carbonate to the water, which give rise to the precipitation of the respective iron, aluminium or calcium orthophosphates, thereby reducing the negative effects related to the excessive presence of phosphorus in the sediments.

Conclusions
Water is not a commercial product like any other but rather a heritage which must be defended and protected, especially in the presence of a global decline in the availability of drinking water and increase in its demand.
Despite the considerable efforts made to improve the water quality by limiting nutrient enrichment, cultural eutrophication and the resulting algal blooms continue to be the main cause of water pollution. The prevention and protection action that countries must adopt to safeguard the quality of surface water as requested not only by the scientific community and other experts, but to an increasing extent also by citizens and environmental organisations, is therefore increasingly important ( ec.europa.eu).
Management of the eutrophic process is a complex issue that will require the collective efforts of scientists, policy makers and citizens.
By Francesca Scannone Bibliographical references

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What is eutrophication? Causes, effects and control - Eniscuola

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After seeing the picture of children swimming in a sea of seaweed, you will surely wonder what strange phenomenon has hit the coast of Qingdao in eastern China. It is an abnormal growth of algae, a clear manifestation of a process called eutrophication. "Eutrophication is an enrichment of water by nutrient salts that causes structural ...

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We all know what kinds of adverse effects water pollution has on humans. What about the effects of water pollution on animals? Let's spare some time to acquaint ourselves with, and ponder upon, the plight of other creatures on planet Earth, due to water pollution.

As we watch the Sun go down, evening after evening, through the smog across the poisoned waters of our native Earth, we must ask ourselves seriously whether we really wish some future universal historian on another planet to say about us: "With all their genius and with all their skill, they ran out of foresight and air and food and water and ideas," or, "They went on playing politics until their world collapsed around them." ~ U. Thant

Although the concern voiced by the former UN Secretary General is valid to the core, the issue is way larger than what opinion some future universal historian on another planet will harbor about the Great Human Race. The issue that we have at hand is of a way more sinister nature. With the reckless acts humanity has been committing in the name of technological and economic progress, that has the future of all life forms on planet Earth hanging by a thread, does it even matter what some historian belonging to an alien race would think of us? I don't think so! Be it soil, water or air, mankind has not spared any of the basic life-sustaining elements from its avaricious clutches.

In fact, these three elements did not suffice to accommodate humanity's materialistic intentions to the complete extent, thereby, prodding Man to look beyond the Earth's atmosphere for furthering his banefully selfish ends. Evidence of this can be seen in form of space waste, which is junk and useless material that no longer serves any purpose to humanity, and has been left to orbit the Earth in the form of space debris. Anyway, speaking of water pollution, its effects are far more harmful and devastating on animals than humans, especially, when those animals happen to be aquatic. Let's take a look at some of the most pronounced ill effects of water pollution on animals.

Water Pollution Effects on Animals

While we humans only feel the harmful consequences of water pollution when we consume contaminated water, go swimming in polluted water sites or make aquatic life forms from polluted water bodies part of our diet, animals are easier victims of the harmful effects of water pollution. While we have the option of treating polluted water to make it safe and drinkable and we can always choose not to bathe in polluted waters or refrain from eating aquatic animals, animals are not capable of resorting to any of these alternatives to escape the toxicity of water that has been contaminated by human and industrial waste.

Some common issues faced by animals from pollution and contamination of water by humans are as follows:-

Chemical contaminants carried by industrial wastes kill a lot of smaller aquatic organisms, such as frogs, fish, tadpoles, etc. This, in turn, causes a loss of food source for bigger aquatic creatures, leading them to either consume poisoned, dead fish and perish, or leave their natural habitat to go in search of food in other aquatic quarters. Often, this leads to sickness and death of these animals due to the inability to adapt to changed water temperatures, unfavorable tides, as well as exposure to new predators.

An excess of nutrients, such as nitrogen and phosphorus in the water, leads to an increased growth of toxic algae and aquatic plants, that cause poisoning and death in fish and other animals who feed on them.

Presence of huge quantities of mercury in water has led to a lot of undesirable changes in aquatic species. Too much mercury leads to hormonal imbalances and glandular damage, leading to abnormal behavioral shifts. Also, mercury is a toxic metallic chemical that gives a huge blow to the reproductive functions, growth and development of animals, that are continuously exposed to high doses of it.

Oil spills that introduce unhealthy amounts of oil into the marine environment also make marine animals sick and lead to their unnatural deaths.

Dumping solid trash such as plastic, metallic scrap, garbage, etc., may block aquatic channels, and can also cause small animals to get trapped in the debris. Most water-dwelling animals tend to suffocate or drown on being trapped and unable to swim.

Polluted water used for irrigation also contaminates the soil and the agricultural produce. This may lead to health issues in herbivorous animals who feed on agricultural plants and leftovers.

These pollutants can radically alter the metabolism of a number of soil-dwelling bacteria and insects, making them perish or unsuitable for consumption by common predators of the local ecosystem.

Atmospheric pollutants may get mixed with clouds and fall back on earth as acid rain. This toxic shower is potent enough to inflict mortal injuries to any life form that gets exposed to it.

These are a few of the most common and prominent repercussions of water pollution on animals. From these points, we can easily see that most animals get hit harder than humans, when water is contaminated. Although huge steps need to be taken on national and industrial levels to arrest this situation before it goes totally out of our hands, individuals can do their small part by refraining from littering beaches and lakes with paper, plastic and other garbage, so that lesser animals make it to the Extinct Species list, and so you can tell your children that the ocean waters still abound in whales, dolphins, turtles, seals, and all those other animals, that are marked as Endangered Species.

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These Tragic Effects of Water Pollution on Animals are Saddening

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We all know what kinds of adverse effects water pollution has on humans. What about the effects of water pollution on animals? Let's spare some time to acquaint ourselves with, and ponder upon, the plight of other creatures on planet Earth, due to water pollution.

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Examples of invasive species; why are they a problem

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Examples of invasive species; why are they a problem

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Where kids go to save animals! - The Kid's Conservation Organization

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Bullying is not just a problem in school yards; it's also a problem in nature! Invasive species are plants and animals that are brought to a new habitat and bully the native species to the point where many can't survive. They are usually hardier, more demanding and reproduce much faster. Since they are new to a habitat, they don't have any natural predators. That means there aren't any species to stop them from taking over an area.

In this top ten, we take a look at ten invasive species from the Global Species Database's 100 most invasive species.

Asian Carp
Asian carp refers to several carp species native to Asia including grass carp, silver carp, bighead carp, black carp, common carp and others.
Native To: Eastern Russia and China

Introduced To: North America and Europe

How did they get there? Asian carp were brought over as food, part of the pet trade and for sport fishing.

Why are they a problem? Asian carp are large, have big appetites and reproduce quickly. They take food and habitat away from native fish and have been known to prey on the eggs of other fish species. When carp eat, they stir up sediments and organisms from the lake and river beds changing a clear lake into murky one and changing the type of species that can survive there.

http://www.issg.org/database/species/ecology.asp?si=60&fr=1&sts=sss&lang=EN
http://yosemite.epa.gov/r10/ECOCOMM.NSF/B724CA698F6054798825705700693650/19CF2902BD848550882574160056CDD1?OpenDocument

Zebra Mussel (Dreissena polymorpha)

Native To: Black, Caspian, Aral and Azov seas

Introduced To: Russia, Europe and North America

How did they get there? Zebra mussels were brought over in ballast water (water carried by ships to help them stay balanced while at sea). They also attach to the outsides of boats or get carried around by floating vegetation.

Why are they a problem? Zebra mussels are one of the most aggressive freshwater invaders because their population numbers grow so quickly. Massive populations of zebra mussels filtering water can severely impact native plankton, which reduces food for fish. These plankton-eating fish then have to find a new source of food or move to a new lake in order to survive. Unfortunately, that isn't an option for many species. Zebra mussels also leave very little for native mussels to filter, causing them to starve as well.
http://www.issg.org/database/species/ecology.asp?si=50&fr=1&sts=sss&lang=EN
Cane Toad (Rhinella marina)

Native To: Northern South America, Central America and Mexico

Introduced To: Many countries with warm climates, like Australia

How did they get there? Cane toads were brought over as a way to control crop pests.

Why are they a problem? Cane toads have an amazing defense mechanism; they produce toxic ooze. While predators in their native habitat are immune to this toxic ooze, predators in other areas are not. Many animals that attempt to eat a cane toad die instead. With nothing around to keep their numbers in check, populations of cane toads in non-native habitats have exploded and they are taking their toll on native animal and plant species.
http://www.issg.org/database/species/ecology.asp?si=113&fr=1&sts=sss&lang=EN
European Starling (Sturnus vulgaris)

Native To: Europe, Asia and Northern Africa

Introduced To: North America, Southern Africa, Australia and New Zealand

How did they get there? European starlings were brought over as a way to control pests, as pets and by a group of people trying to introduce all the birds mentioned in the works of Shakespeare into North America.

Why are they a problem? European starlings form huge flocks, many times with more than 3,000 birds. When a flock this size feeds on fruit and grains, it can cause serious damage to a farm. These birds are also aggressive, fighting with native species over food and territory. They will even take over other birds' nests, leaving native birds without a place to lay their eggs or raise their young.
http://www.issg.org/database/species/ecology.asp?si=74&fr=1&sts=sss&lang=EN
The European/Common Rabbit (Oryctolagus cuniculus)

Native To: Southern Europe and North Africa.

Introduced To: All continents except Antarctica and Asia

How did they get there? Rabbits were brought over as a source of food and as a way to remind people of the country they came from during colonial times.

Why are they a problem? Rabbits reproduce very quickly. In one year, one female can have between 18-30 babies! Their population numbers grow so large and they eat so much that they have pushed native plant species to the brink in certain areas. They also compete for food and shelter with native animals, causing a decline in the number of native species in the area. They have caused soil erosion from burrowing and overgrazing, leading many species who depend on that environment to suffer.
http://www.issg.org/database/species/ecology.asp?si=18&fr=1&sts=sss&lang=EN
Kudzu (Pueraria montana var. lobata)

Native To: Eastern Asia and some Pacific Islands

Introduced To: North America and Europe

How did they get there? Kudzu has been sold as a plant for gardens and for eating.

Why are they a problem? Kudzu is an aggressive vine, capable of growing up to 26 cm (a little less than 1 ft.) a day. Since it expands so quickly, it smothers other plants, stopping them from having access to sunlight. Kudzu can even kill mature trees. This prevents native plants from growing and changes the ecosystem structure. What's even worse is that once kudzu starts growing, it is extremely difficult to get rid of.
http://www.issg.org/database/species/ecology.asp?si=81&fr=1&sts=sss&lang=EN
Asian long-horned beetle (Anoplophora glabripennis)

Native To: China, Japan, Korea

Introduced To: North America and Europe

How did they get there? Asian longhorn beetles were brought over in shipments of wooden packaging materials and trees

Why are they a problem? Asian longhorn beetles aren't picky about where they lay their eggs; almost any deciduous tree will work. As larvae, they eat the soft sappy bark, which makes it hard for nutrients to reach other parts of the tree. As they grow, the larvae burrow into the middle of the tree leaving large tunnels as they move, making the tree physically weaker. As adults, Asian longhorn beetles emerge from the tree, breaking through the bark leaving large holes. Many trees don't survive once they are infested with Asian longhorn beetles.

http://www.issg.org/database/species/ecology.asp?si=111&fr=1&sts=sss&lang=EN
http://www.mnr.gov.on.ca/en/Business/Forests/2ColumnSubPage/STEL02_166979.html

Small Indian mongoose (Herpestes auropunctatus)

Native To: Southeast Asia

Introduced To: Asia, Central America, South America

How did they get there? Small Indian mongooses were brought over for pest control for rats and snakes.

Why are they a problem? Small Indian mongooses are aggressive predators. They are blamed for the decline of bar-winged rail (extinct), Jamaica petrel (critically endangered and possibly extinct), hawksbill turtles (critically endangered), pink pigeon (endangered), Amami rabbit (endangered) and many other birds, reptiles and mammals. Mongooses also carry rabies and other human diseases.
http://www.issg.org/database/species/ecology.asp?si=86&fr=1&sts=sss&lang=EN
Northern Pacific seastar (Asterias amurensis)

Native To: Waters around China, Japan, Korea

Introduced To: Australia

How did they get there? Northern Pacific seastars were brought over in ballast water (water carried by ships to help them stay balanced while at sea). They can also be attached to boats and fishing equipment or be transported along with live fish.

Why are they a problem? Northern Pacific seastars are aggressive eaters. They will eat almost anything they can find. To make matters worse, Northern Pacific seastars reproduce very quickly. In one area where they were introduced, their population reached an estimated 12 million seastars in just two years. They have been blamed for the decline of the critically endangered spotted handfish.
http://www.issg.org/database/species/ecology.asp?si=82&fr=1&sts=sss&lang=EN
Water hyacinth (Eichhornia crassipes)

Native To: The Amazon basin and waterways of Western Brazil, South America

Introduced To: Africa, Asia, North America, Australia and New Zealand

How did they get there? Water hyacinth was brought over as a decorative plant, for animal food, as part of the aquarium trade, by getting stuck on boats and through the spreading of seeds

Why are they a problem? Water hyacinth is a fast growing water plant. They are known as one of the world's worst weed, found in more than 50 countries. In the right conditions, a small patch of water hyacinth can double in size in just 6 days! These plants are thick and dense, clogging up rivers and making in nearly impossible for animal life to move through them. They block sunlight and oxygen from getting to other plants below the water, causing the ecosystem to change dramatically.
http://www.issg.org/database/species/ecology.asp?si=70&fr=1&sts=sss&lang=EN
If you think animals are amazing, the Earth Rangers Podcast is for you!

Join Earth Ranger Emma as she travels the world on a quest to solve some of nature's greatest mysteries! With top ten countdowns, animal guessing games and epic animal showdowns, this is a journey you won't want to miss!

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Ten of the World's Most Invasive Species - Where kids go to save animals!

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An invasive species might look harmless but if not controlled it can destroy an ecosystem. In this top 10 we take a look at ten of the worst.

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Water pollution has become and epidemic in the United States. It has affected our homes and communities in ways that you can't imagine. Despite our prevention efforts it continues to ravage our country, and in turn our lives as well.

If you're worried about water pollution in the United States, you're certainly in the RIGHT PLACE. Read on...

Water pollution in the United States is a real problem, and if you're worried about it, you're in the right place. In this article, you'll be introduced to the problem of water pollution in America as well as its many different sources. You'll learn what steps are being taken to get rid of pollution and help prevent it in areas that haven't been seriously affected yet, and you'll even find out a little more about pollution in the neighboring countries of Canada and Mexico too.

By the time you've finished with this article, you'll know everything you need to know to get started fighting against water pollution where you live. You'll be well prepared with plenty of information and education so you'll know exactly what the situation is in your area.
Read on to find out more.

27 Facts about Water Pollution in the US

In order to understand water pollution in the US, it's important to know some facts about how it has affected our nation. Some of these facts may be disturbing, but remember that it's always important to know just what's going on in the world around you and especially in the country where you live.

It might be hard to read some of this, but in educating yourself on the subject of water pollution in USA cities, you'll be better able to find out just how you can get involved. The more you know, the more you'll be able to work to make a difference.

1. In the past 12 years, drinking water used by 49 million residents of the United States has been contaminated with bacteria, radioactive materials, and arsenic in levels that are both illegal and incredibly unsafe.

This means that the Safe Drinking Water Act has been violated severely by over twenty percent of the United States' water treatment facilities. Most of these water treatment facilities did nothing about it, and most of them were never fined or given anything other than a verbal warning to improve their water quality. While some of these were one-time problems, many of these facilities continue to provide poor quality water to United States residents today.

2. Since 2004, tap water containing unsafe and illegal levels of harmful bacteria has been provided through 205 different water treatment facilities in New York state alone.

3. Every year, the Mississippi River brings 1.5 million metric tons of pollution, mostly in the form of nitrogen, from land throughout the southern United States into the Gulf of Mexico.

When this happens, a massive dead zone forms in the Gulf, killing off almost all of the plant, fish, and animal life there. This dead zone is close to the size of the state of New Jersey, and it only expands every year.

4. Every year, water in the United States is contaminated with 1.2 trillion gallons of stormwater, industrial runoff wastewater, and sewage that are dumped into freshwater sources throughout the country.

Even if these substances aren't purposefully dumped in freshwater supplies, they still often enter them by way of groundwater contamination anyway. More practices need to be put in place to regulate and clean up the removal of waste products from various industries, but we aren't there yet. Unfortunately, even in industries where regulations are present, they aren't very widely enforced.

5. There are many lakes throughout the United States.

However, about 40% of them are too polluted for human interaction, and it's unsafe to fish in, swim in, or drink from them. The causes of this type of pollution vary from lake to lake, but it usually has something to do with bacteria that have grown out of control due to dumping and waste products present in the water sources. It's getting more and more common to see signs posted warning people not to go into lake water even in some of the most protected parts of the United States.

6. Agricultural practices use 70% of all water consumed in the United States every year.

However, they are also the number one cause of water pollution in this country. Unfortunately, there aren't a lot of steps being taken on a nationwide scale to cut back on water pollution from agricultural practices, even though there are more and more small farmers working to improve the quality of groundwater surrounding their farms. Pollution from pesticides and other agricultural substances continues to drift down rivers and into the oceans and the Gulf of Mexico.

7. Wetlands provide a huge amount of drinking water to some of the most populated cities in the United States.

Unfortunately, over half of the wetlands in existence since 1900 have completely dried up and disappeared. 13 million hectares of forest and wetlands are lost every year due to water pollution and a lack of water conservation. This is mostly related to poor groundwater practices, but it also has something to do with air pollution as well as with dumping in these areas. Wetlands protection is slowly being enacted, but it's taking a long time.

8. While global warming is a controversial, hot-button topic, it is contributing to the problem of water pollution as well as a lack of clean drinking water around the world-not just in the United States.

It's believed that residents of highly populated cities in the United States will see a reduction in clean drinking water because of global warming by the year 2050 and that these residents will be forced to live on 100 liters of water per day. This isn't very much water for sustaining a healthy lifestyle.

9. Every day in the United States, 7 billion gallons of perfectly good, clean drinking water are wasted because of leaking pipes and water infrastructure that hasn't been maintained and cleaned properly throughout the years.

10. In Michigan has caught the attention of media around the country over the past two years, and with good reason.

In the city of Flint, Michigan, levels of lead in the water supply are so high that they're too toxic for human consumption and have been known to cause lead poisoning. Lead corrosion quickly took place in the pipelines throughout the city, and it still hasn't been cleaned up. The residents of Flint, Michigan, have had unsafe drinking water for two years with no promise of this changing.

11. Michigan isn't the only state with problems in their drinking water.

West Virginia water pollution has been heavily discussed in recent years, too, in the wake of the Elk River chemical spill. In 2014, a chemical called MCHM leaked into the Elk River and contaminated the water downstream in the city of Charleston, West Virginia. The areas affected included nine counties, and residents still believe the water hasn't been completely cleaned up today.

12. Water pollution in California runs rampant today too.

12. Water pollution in California runs rampant today too.

Four hundred rural communities in California alone can't provide clean drinking water to their residents because of high levels of nitrate in the water. This comes from fertilizers, pesticides, and other sources originating from agricultural practices. Arsenic pollution is also on the rise in these communities. Unfortunately, since these are areas where the population is small, the payoff for cleaning up the water isn't deemed worth it, and they're usually left to suffer because of economic problems. Lower income communities around the United States continue to be afflicted with dirty, unsafe drinking water.

13. Yearly spending on water cleanup in California clocks in at around $10 billion.

This mostly goes to water treatment facilities, where it is vital to clean up water before it reaches individuals throughout the state. Stormwater cleanup programs cost the state a lot, too, and come in at least at $500 million in spending every year. Despite all this money put toward cleaner water and safer practices, California still sees a lot of water pollution and contamination anyway.

14. Salt is a common pollutant in California.

While salt in water isn't necessarily a pollutant in some circumstances-and may be simply classified as a contaminant in many situations-in California, it so severely affects freshwater sources that it has become a major pollution problem. It comes from animal waste and fertilizers as well as human waste and even from the nearby ocean. This type of pollution affects farmlands and agricultural practices in a very negative way, even though they also often contribute to the problem.

15. Water pollution in Florida continues to pose both risks to human health as well as dangers to the surrounding environment.

There are many lakes in Florida, but the largest by far is Lake Okeechobee. This lake, unfortunately, is heavily polluted due to the many factories and other industries that have been dumping waste, chemicals, and fertilizer in the lake for decades. Water flows from Lake Okeechobee at a rate of 70,000 gallons per second, and it eventually empties into the Gulf of Mexico. Communities on the Gulf Coast have begun to see serious pollution problems from the flow of water that comes from this large inland lake.

16. Florida's water pollution has led to algal blooms which have choked out a lot of marine life in the coastal regions surrounding the state.

This has led, in turn, to a serious decline in shellfish populations, which leaves many fishermen without jobs or a means of supporting themselves or their families. Similarly, since Florida relies so heavily on tourism as a source of income, the state is suffering due to the serious water pollution problems keeping visitors away.

17. In Florida and other coastal states, about ¼ of the beaches in the United States close for at least part of the year every year due to water contamination.

This causes a lot of extended problems. For one thing, when water at freshwater and saltwater beaches is contaminated, plant, animal, and fish life is severely affected as well. When these beaches are forced to close, tourism takes a hit in these areas as well, which can, in turn, affect the quality of life of the individuals who rely on this industry for their income. In some extreme circumstances, beaches are never able to fully open again, and businesses are forced to relocate, leaving the surrounding area basically a ghost town.

18. Every year, over two billion pounds of pesticides are used in the United States agricultural industry alone.

This huge number of chemicals is made up of over seventy different types of pesticides. Unfortunately, a very large amount of these pesticides ends up polluting freshwater sources throughout the United States yearly as well. This type of pollution is very common, especially in areas where agricultural practices are prevalent. This means that much of the rural part of the country faces groundwater pollution caused by toxic chemical runoff from these pesticides every year.

19. Residents of the United States use more water in a daily shower than people in many developing countries have access to for everything in an entire day.

A five-minute shower uses more water than you might think, and although limiting your shower to only five minutes is a good step to take toward water conservation, it's still using a lot more water than many people worldwide have access to on a regular basis.

20. According to the EPA water quality assessment in 2012, only two states have seen drastic reductions in polluted, contaminated, and otherwise impaired waterways.

Of the remaining 48 states, 14 of them have between one and five thousand polluted sources of freshwater within their boundaries, and one state-New York-has more than five thousand. Although many of these states have seen steps in the right direction, there's still a long way to go.

21. According to a 2010 EPA water quality assessment, chromium-6 is present in 35 different United States cities alone, disregarding smaller and less populated communities that might be affected as well.

This substance leads to cancer as well as birth defects and other threats to human health. While it's unknown how many smaller residential communities also face contamination from chromium-6, it's safe to assume that there are several. Unfortunately, this substance is very hard to filter out of water sources, and most places where it's present are unable to get rid of it completely. This means that some individuals drink water contaminated with chromium-6 for their whole lives.

22. In 2016, a Harvard study found PFASs, another very harmful chemical substance, in water from 33 of the 50 states, and determined that over six million United States residents were affected by these contaminated water supplies.

PFASs are linked to cancer, birth defects, and hormone-related diseases and disorders in both humans and animals. In the states where this pollutant is widespread in water sources, cancer rates are notably higher than they are in states where this pollutant isn't present.

23. In 2014, four different states confirmed water pollution related to drilling and fracking in various places throughout the states

Fracking is a huge topic of controversy throughout the United States, and for a long time, industries that relied on fracking firmly believed that there was no way this process could be contaminating water. However, since then, Pennsylvania, West Virginia, Ohio, and Texas have all confirmed the presence of pollutants and contaminants in water in places where fracking occurs. In the years since their initial confirmations, however, the number of pollutants has decreased due to safer water practices and more concern for water sources.

24. The list of endangered species in the United States grows every year, largely due to water pollution.

Especially in the wetlands, where pollution has reached staggering levels in the past few decades, more and more species are beginning to disappear. In the United States alone, the U.S. Fish and Wildlife Service has recognized 1,361 endangered species of animals and plants as of 2009. That number has only risen since then, and unfortunately, some of these species are gone forever.

25. The Mississippi River is the most polluted river in the United States.

Coming in right behind it are the Ohio River and the Tennessee River. All three of these Rivers affect the southern United States, so this part of the country is especially contaminated in terms of water sources. The state of Kentucky is affected by all three of these rivers and their water contamination, and the states of Tennessee and Alabama are affected by two of the three of them. Unfortunately, many of these states also have lower incomes than others, so economics plays a big part in their inability to clean up their water sources.

26. The Ohio River is seriously contaminated because of chemical dumping from the Dupont industry starting in the 1950s.

This dumping wasn't regulated for many decades, leading to a dangerous buildup of PFOA, which causes cancer in both animals and in humans. PFOA cannot be removed from the environment once it enters it, and so the Ohio River is likely going to be contaminated by this chemical forever. Many humans have some levels of PFOA in their blood since this chemical is present in cleaners, popcorn bags, cookware, and more.

27. The American Water Works Association estimates that it would take several trillion dollars to repair the over two hundred thousand water main breaks and leaks throughout the United States water supply infrastructure.

This would take a huge overhauling of spending practices throughout the country, and there are no signs of a change like this taking place anytime soon. It's an unfortunate truth that the nation may not have enough money to really clean up the water as needed.

BONUS: Facts about Canada and Mexico

Water pollution in Mexico and Canada can be just as serious as it is in the United States. To better understand the situation throughout all three of these countries, it is important to know what's going on in each one individually. Check out this bonus list of facts about water pollution in Canada and Mexico, and you'll be one step closer to figuring out the best way you can get involved no matter where you live. You might also learn something about the difference in water contamination between the United States and its two closest neighbors, too, which is a great way to help you better examine the state of the water where you live.

Water Pollution in the US

Water pollution in the United States is a major problem. It affects the entire nation, but some places have much more serious problems with water pollution than others. If you're lucky enough to live in a place where this type of pollution isn't a very big problem, you might not realize just how bad it's getting elsewhere in your own home country. However, it's important to keep in mind the condition of the water throughout the United States, and not just in your own personal area. If possible, you should always take steps to help cut back on the spread of water pollution throughout the nation.

There are a few things you should keep in mind when considering the United States and water pollution. Here is a list of ideas that can help you get started understanding this problem and where it's headed in the future.

Pollution and contamination aren't the same things. Most of the water in the United States is contaminated with something, but this doesn't necessarily mean it's polluted. However, when contaminants cause a threat to human life or well-being, they become pollutants. This is an unfortunate problem in a lot of the freshwater sources in the United States today.

Groundwater is even more heavily polluted than surface water in most places. Groundwater collects and absorbs lots of different types of pollutants, from chemicals to bacteria to poisonous natural substances. When this happens, it carries the pollutants slowly through the soil until they reach surface water sources. From there, the pollutants build up in the water supply and eventually reach residents as drinking water.

Water treatment facilities are incapable of removing all pollutants from the water. Even the most updated and well-kept of these facilities can't make a big difference when water is very badly polluted. Because of this, water in many areas is unfit to drink even though it's being used by residents of these areas on a regular basis.

Sources of Water Pollution in the US

In the United States alone, there are several different sources of water contamination and pollution. Some are more prevalent than others, but all of them are serious problems that need to be considered and cleaned up. Different types of water pollution cause different issues, so depending on where you live, you might see a variety of different problems associated with dirty water. Pay careful attention to potential problems that might arise from contaminated water in your city or state, and don't be afraid to reach out to people in positions of power to find out more about what's going on.

Agriculture - This is by far the largest contributor to water pollution in the United States. The agricultural industry causes a significant amount of water pollution in the country every year, and unfortunately, it hasn't been very heavily regulated until recent decades. While you might think that agricultural practices should be more concerned with the quality of water they use to grow plants and raise animals, they usually aren't, and they allow waste, pesticides, and even dead animals to contaminate water supplies surrounding agricultural areas across the country.

Other industries - Factories and other industries also contribute to water contamination in the United States. Factories have been dumping wastewater and even chemical waste into freshwater sources for decades, and although some regulations have been put into place to try to stop this, there hasn't been a lot of change made. Travel industries also contribute to the problem, and the burning of fuel and oil leads to air pollution that in turn affects clean water sources across the country. In cities where air pollution is heavy, water pollution is also very common.

Nuclear power - Where nuclear power plants are present, water is seriously contaminated. This water is completely unsafe for human use, and if plants and fish are still able to live in the water, they are usually poisoned or severely damaged in some way. Unfortunately, many rural parts of the United States are built around these power plants, and the people who live in these areas suffer greatly because of it. Cancer and birth defects are much more common in these areas, but many of these communities are lower income and can do nothing about it.

Fracking and mining - Fracking and mining both contribute to natural chemicals rising in water sources throughout the United States. They cause poisonous substances to quickly reach water supplies, and they can cause arsenic and lead poisoning, as well as other types of pollution and contamination. In cities close to fracking sites, water quality decreases very quickly while fracking is under way.

Residential chemical use - Larger residential communities contribute to groundwater pollution every time chemicals are used. Chemicals used to clean cars and the outside of homes, to treat lawns and home gardens for pests, and to clean up swimming pool and hot tub water are all potential threats to groundwater quality. When these chemicals spill or are washed into yards, they can reach groundwater easily and further pollute freshwater sources in the area significantly.

Residential chemical use - Larger residential communities contribute to groundwater pollution every time chemicals are used. Chemicals used to clean cars and the outside of homes, to treat lawns and home gardens for pests, and to clean up swimming pool and hot tub water are all potential threats to groundwater quality. When these chemicals spill or are washed into yards, they can reach groundwater easily and further pollute freshwater sources in the area significantly.

Landfills and runoff - Landfills are an important part of any waste reduction, and it's always a good idea to dump garbage and landfills. However, most people dispose of waste improperly at landfills, which causes more groundwater contamination. There are many substances that should be disposed of properly at dedicated waste sites, and these can cause chemical and bacterial pollution in groundwater surrounding landfills. This is a huge problem in the United States.

Actions Taken Against Water Pollution in the US

There are many actions taken regularly in the United States to help cut back on the amount of water pollution around the country every year. These actions mostly come in the form of policies and laws, but not always. Unfortunately, a lot of these policies are difficult to actually enact, so while they sound good on paper, they don't always make a big difference in the long run. Even so, more and more people are beginning to be concerned with the state of water in the United States, so the situation is slowly but surely shifting.

Pollution Prevention Act - The Pollution Prevention Act was passed in 1990 after it became more widely known that industries were contributing significantly to the massive amounts of pollution entering into the water and atmosphere every year in the United States. The Act focused on reducing pollution at the source, which meant it regulated industries' abilities to dump hazardous or toxic waste or release this waste into the environment in any way. It also states that releasing these wastes into the environment must only be done as an absolute last resort, and it encourages recycling whenever possible.

Executive Order - Executive Order 13693, which was signed by President Obama in 2015, encourages environmentally friendly and sustainable practices by federal agencies. It makes it against the law for any federal agency to receive items or conduct daily, routine business in a way that could be damaging to the environment. This Order revoked two previous Orders that were meant to work toward this ultimate goal.

Clean Water Act - The Clean Water Act is the basis for most regulations against the dumping of toxic chemicals and pollutants into water throughout the United States. This Act was enacted in 1948 but was changed into its more modern-day version in 1972. The Act regulates wastewater standards for various industries across the board, and it tries to offer a solution that will work well for the environment as well as for the businesses, factories, and farms that need to remove waste. However, it also allows for some workarounds by way of getting a dumping permit. Although the Clean Water Act has been around for a long time, it hasn't made as many changes as it should have in the area of dumping and storage of toxic chemicals. It does lead to more frequent inspections and investigations, but even so, problems go unnoticed and untreated for years in many instances.

State level regulations - In a lot of situations, regulations of various industries are up to the states to decide. Different states have different regulations, and some are a lot more forward-thinking in terms of water pollution than others. You might live in a state where these rules are very strict already, or you might live in one where you can get involved trying to make a difference by enforcing stricter ones. Get in touch with your state's government to find out more about regulations where you live.

City and county regulations - Much like the individual states' regulations in terms of water pollution, cities and counties sometimes have their own as well. It depends on where you live what sort of regulations you have in your area. You can usually contact your local water treatment facility to find out more, or you can contact your own water supplier to ask how to learn more instead.

Organized cleanups - Many communities have regularly organized water cleanup days. Although this doesn't do anything for dissolved pollutants and contaminants like chemicals and bacteria, it can still make a big difference in the long run when it comes to reducing the amount of water pollution in your area. If you live in a place where regular river and lake cleanups take place, be sure to get involved with them whenever possible. And if you don't, don't be afraid to start up your own and see if you can get your friends, family and neighbors involved. This is a great way that many communities throughout the United States are taking action to make a difference.

Conclusion

Learning about water pollution where you live is one of the first steps you can take toward making a difference. Now that you've read through this article, you've found out a lot about what's going on in the United States, as well as how water quality is changing for its neighbors, Canada and Mexico. From here, it's entirely up to you how you choose to get involved. Whether you decide to make changes around your home to ensure that you aren't contributing further to water pollution and contamination in your area or you want to get out there and start advocating locally or on a nationwide scale for the cleanup of water sources, you can easily find your place in the fight against water contamination.

One of the best ways for you to fight against pollution is to get a friend or family member involved with you. While it's entirely possible to fight for a cause you believe in on your own, when you have some support that's close to you and someone to share your beliefs with, you can make an even bigger difference in no time. Don't be afraid to reach out to the people you know and see if someone else will be interested in helping you speak out against water pollution. You never know when someone in your neighborhood might be waiting for the same opportunity!

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27 Alarming Facts About Water Pollution in the United States (END GAME)

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Water pollution has become and epidemic in the United States. It has affected our homes and communities in ways that you can't imagine. Despite our prevention efforts it continues to ravage our country, and in turn our lives as well. If you're worried about water pollution in the United States, you're certainly in the RIGHT PLACE.

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Air Pollution (How do we cause Air Pollution

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Air Pollution (How do we cause Air Pollution

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We cause air pollution directly through our use of electricity, fuels, and transportation.

We also cause air pollution indirectly, when we buy goods and services that use energy in their production and delivery. Most of this air pollution we cause results from the burning of fossil fuels, such as coal, oil, natural gas, and gasoline to produce electricity and power our vehicles.

Carbon dioxide (CO2) is a good indicator of how much fossil fuel is burned and how much of other pollutants are emitted as a result. Using carbon dioxide as an example, the average family in the United States causes air pollution in the following ways:

How Much Air Pollution Do We Cause?
An average family in the United States causes the following amounts of air pollution each year:

Climate Change Pollution (CO ₂) = 85 Tons
Ozone-Causing Pollution (NOx) = 325 Pounds
Acid Rain Causing Pollution (SO ₂) = 411 Pounds
Small Particulate Pollution = 43 Pounds
Toxic Lead Pollution (Pb) = 1.2 Ounces
Toxic Mercury Pollution (Hg) = 0.04 Ounces

Find out how much pollution is caused by your household electricity use with the Cleaner and Greener Pollution Calculator .

And each year, the average individual in the United States causes the following amounts of air pollution:

Climate Change Pollution (CO ₂) = 27 Tons
Ozone-Causing Pollution (NOx) = 102 Pounds
Acid Rain Causing Pollution (SO ₂) = 129 Pounds
Small Particulate Pollution = 14 Pounds
Toxic Lead Pollution (Pb) = 0.4 Ounces
Toxic Mercury Pollution (Hg) = 0.01 Ounces

The following table summarizes some sources and effects of these air pollutants.
Sources and Effects of Common Air Pollutants

Secondary pollutant formed by chemical reaction of VOCs and NOx in the presence of sunlight.

Breathing problems, reduced lung function, asthma, irritates eyes, stuffy nose, reduces resistance to colds and infections, premature aging of lung tissue.

Damages crops, forests, and other vegetation; damages rubber, fabric, and other materials; smog reduces visibility.

Burning of gasoline, natural gas, coal, oil.

(Cars are a major source of NOx.)

Lung damage, respiratory illnesses, ozone (smog) effects.

Ozone (smog) effects; precursor of acid rain which damages trees, lakes, and soil; aerosols can reduce visibility.

Acid rain also causes buildings, statues, and monuments to deteriorate.

Burning of gasoline, natural gas, coal, oil.

Reduces ability of blood to bring oxygen to body cells and tissues.

Fuel combustion, solvents, paint.

(Cars are a major source of VOCs.)

Ozone (smog) effects, cancer, and other serious health problems.

Ozone (smog) effects, vegetation damage.

Emitted as particles or formed through chemical reactions; burning of wood, diesel, and other fuels; industrial processes; agriculture (plowing, field burning); unpaved roads.

Eye, nose, and throat irritation; lung damage; bronchitis; cancer; early death.

Source of haze which reduces visibility.

Ashes, smoke, soot, and dust can dirty and discolor structures and property, including clothes and furniture.

Burning of coal and oil, especially high-sulfur coal; industrial processes (paper manufacturing, metal smelting).

Respiratory illness, breathing problems, may cause permanent damage to lungs.

Precursor of acid rain, which can damage trees, lakes, and soil; aerosols can reduce visibility.

Acid rain also causes buildings, statues, and monuments to deteriorate.

Combustion of fossil fuels and leaded gasoline; paint; smelters (metal refineries); battery manufacturing.

Brain and nervous system damage (esp. children), digestive and other problems. Some lead-containing chemicals cause cancer in animals.

Harm to wildlife and livestock.

Fossil fuel combustion, waste disposal, industrial processes (incineration, smelting, chlor-alkali plants), mining.

Liver, kidney, and brain damage; neurological and developmental damage.

Accumulates in food chain.

Health Effects of the Pollution We Cause
Exposure to emissions of lead, mercury, sulfur dioxide, particulate matter, carbon dioxide, and ozone-forming nitrogen dioxides are hazardous to public health. Toxic compounds, like mercury and lead, poison organ systems and can lead to brain damage and death. In parts of the country where lakes and waterways have been contaminated with mercury from electric power plants, fish are no longer safe to eat because they, too, are contaminated with heavy metal pollutants. Other pollutants, like ozone and particulate matter, cause respiratory and other health problems, particularly in children and the elderly.
Environmental Effects
Climate change on a global scale has been attributed to increased emissions of carbon dioxide (CO ₂), a greenhouse gas. A global average temperature rise of only 1C could have serious implications. Possible consequences include melting of polar ice caps; an increase in sea level; and increases in precipitation and severe weather events like hurricanes, tornadoes, heat waves, floods, and droughts. Indirect effects include increases in infectious disease, weather-related deaths, and food and water shortages. All these effects put a stress on ecosystems and agriculture, and threaten our planet as a whole.

Other atmospheric effects of air pollution include urban smog and reduced visibility, associated with ozone-forming nitrogen oxides and volatile organic compound emissions. Sulfur dioxide and nitrogen oxides combine with water in the atmosphere to cause acid rain, which is detrimental to forests and other vegetation, soil, lakes, and aquatic life. Acid rain also causes monuments and buildings to deteriorate.
Economic Effects
The effects of air pollution on human health and the environment have economic impacts. According to the Healthy People 2000 report , each year in the United States:

The health costs of human exposure to outdoor air pollutants range from $40 to $50 billion.

An estimated 50,000 to 120,000 premature deaths are associated with exposure to air pollutants.

People with asthma experience more than 100 million days of restricted activity, costs for asthma exceed $4 billion, and about 4,000 people die of asthma.

The Environmental Defense Fund (EDF) article, "Why is it Better to Buy Green Electricity?" , states that acid rain causes $6 billion a year in damage to crops, forests, lakes, and buildings. The potential economic impact of global warming is estimated to be in the billions of dollars. While green sources of electricity may cost more, they do not incur the external costs of traditional fossil fuel-based generation. The EDF article states that:

"Increasing reliance on green sources reduces financial risks such as future regulations, taxes on greenhouse gases, and price fluctuations associated with fossil fuels. Green resources increase U.S. energy self sufficiency, and thus economic security, by reducing reliance on fossil fuel imports. They also help reduce current rapid depletion of natural resources.

Green resources are a good source of jobs and income because they rely on local labor, land, and resources. Rural communities would probably benefit the most from renewable energy development, as wind and biomass energy production is likely to take place in rural areas."
What You Can Do
There are many actions people of all ages can take to reduce their emisisons. To learn more, read the checklist of things you can do in your home and in your school in the Cleaner and Greener Program's " ." If we all work together, we can make the world a cleaner and greener place to live! Green Marketing and websites provided by Guide to Air Pollution and the Emissions We Cause Custom Creative

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We cause air pollution directly through our use of electricity, fuels, and transportation. We also cause air pollution indirectly, when we buy goods and services that use energy in their production and delivery. Most of this air pollution we cause results from the burning of fossil fuels, such as coal, oil, natural gas, and gasoline to produce electricity and power our vehicles.

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Each year, 46 to 58 million square miles of forest are lost due to deforestation -- the removal of trees from the land by man-made and natural events. Deforestation is caused by land-clearing for urban development and agriculture, tree harvest for wood products, and forest fires. The loss of trees has an adverse affect on the air.

TL;DR (Too Long; Didn't Read)

Deforestation has an adverse affect on air by reducing the amount of oxygen and increasing the amount of carbon dioxide as well as contributing to global warming.

Trees and plants, in general, produce energy for growth using a process known as photosynthesis. Using light, water and carbon dioxide, a plant produces energy in the form of sugar and releases oxygen into the air. Forests cover approximately 30 percent of the land on earth and sustain nearly 80 percent of the world's terrestrial organisms. It is estimated that one acre of trees in urban forests can produce enough oxygen for eight people and remove 188 pounds of carbon dioxide from the air.

Oxygen comprises only about 21 percent of air's chemical component. Yet, it is extremely important to life on earth. Living organisms, from single-celled animals to humans, use oxygen to produce the energy required to sustain them. Since trees are larger plants, their production of oxygen is significant. It is estimated that tropical rainforests, produce 40 percent of the earth's oxygen even though they cover only about 6 percent of the land. Rainforests in the Amazon have declined by 17 percent in the last 50 years as a result of deforestation.

Carbon dioxide is one of the greenhouse gases that help to hold heat in the atmosphere. Trees remove some of this carbon dioxide from the air through photosynthesis and store that carbon in their tissues and in the soil. This process is known as carbon sequestration. Since the industrial revolution began in the mid-1700s, more greenhouse gases have been released than removed from the air. In 2011, forests in the United States removed only about 14 percent of the carbon dioxide emitted into the air. Deforestation reduces the removal component of this cycle, further increasing the carbon dioxide in the air. This results in an increase in temperature, an effect known as global warming.

Not only does deforestation contribute to global warming by increasing the amount of carbon dioxide in the air but it also directly increases the temperature radiating from the land. The forest canopy shades the ground, absorbs the sun's rays for photosynthesis, and reflects about 12 to 15 percent, cooling the land beneath. This holds moisture in the soil that carries nutrients through the roots into the plant. Plants then release water vapor into the air through their leaves in a process known as transpiration. A single leaf can release more water into the air than its own weight. Water vapor in the air accumulates and falls as rain, cooling the land and carrying nutrients back to the plants. Without forests, the land would radiate and reflect heat back into the air, adding to global warming. It is estimated that trees in tropical rainforests lower the temperature by 3.6 to 6.3 degrees Fahrenheit. In the past century, the average temperature around the world has increased by 1.4 degrees Fahrenheit.

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Deforestation, or clearing the land of trees, has detrimental effects on air. Removing wide areas of trees results in less oxygen being produced, more carbon dioxide in the air and higher global temperatures.

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You may use the outline on the right side of the website to navigate to specific resources:)

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Population growth is one of the most important topics we cover at Our World in Data.

For most of human history, the global population wasa tiny fraction of what it is today. Over the last few centuries, the human population has gone through an extraordinary change. In 1800, there were one billion people. Today there are more than 8 billion of us.

But after a period of very fast population growth, demographers expect the world population to peak by the end of this century.

On this page, you will find all of our data, charts, and writing on changes in population growth. This includes how populations are distributed worldwide, how this has changed, and what demographers expect for the future.

Key insights on Population Growth

Population cartograms show us where the world's people are

Geographical maps show us where the world's landmasses are; not where people are. That means they don't always give us an accurate picture of how global living standards are changing.

One way to understand the distribution of people worldwide is to redraw the world map - not based on the area but according to population.

This is shown here as a population cartogram: a geographical presentation of the world where the size of countries is not drawn according to the distribution of land but by the distribution of people. It's shown for the year 2018.

As the population size rather than the territory is shown in this map, you can see some significant differences when you compare it to the standard geographical map we're most familiar with.

Small countries with a high population density increase in size in this cartogram relative to the world maps we are used to - look at Bangladesh, Taiwan, or the Netherlands. Large countries with a small population shrink in size - look for Canada, Mongolia, Australia, or Russia.

You can find more details on this cartogram in our article about it:

What you should know about this data

This map is based on the United Nation's 2017 World Population Prospects report. Our interactive charts show population data from the most recent UN revision. This means there may be minor differences between the figures shown on the map and the latest estimates in our other charts.

The world population has increased rapidly over the last few centuries

The speed of global population growth over the last few centuries has been staggering. For most of human history, the world population was well under one million.¹

As recently as 12,000 years ago, there were only 4 million people worldwide.

The chart shows the rapid increase in the global population since 1700.

The one-billion mark wasn't broken until the early 1800s. It was only a century ago that there were 2 billion people.

Since then, the global population has quadrupled to eight billion.

Around 108 billion people have ever lived on our planet. This means that today's population size makes up 6.5% of the total number of people ever born.²

This increase has been the result of advances in living conditions and health that reduced death rates - especially in children - and increases in life expectancy.

What you should know about this data

This data comes from a combination of sources, all detailed in our sources article for our long-term population dataset.

Population growth is no longer exponential - it peaked decades ago

There's a popular misconception that the global population is growing exponentially. But it's not.

While the global population is still increasing in absolute numbers, population growth peaked decades ago.

In the chart, we see the global population growth rate per year. This is based on historical UN estimates and its medium projection to 2100.

Global population growth peaked in the 1960s at over 2% per year. Since then, rates have more than halved, falling to less than 1%.

The UN expects rates to continue to fall until the end of the century. In fact, towards the end of the century, it projects negative growth, meaning the global population will shrink instead of grow.

Global population growth, in absolute terms - which is the number of births minus the number of deaths - has also peaked. You can see this in our interactive chart:

The world has passed "peak child"

Hans Rosling famously coined the term " peak child " for the moment in global demographic history when the number of children stopped increasing.

According to the UN data, the world has passed "peak child", which is defined as the number of children under the age of five.

The chart shows the UN's historical estimates and projections of the number of children under five.

It estimates that the number of children in the world peaked in 2017. For the coming decades, demographers expect a decades-long plateau before the number will decline more rapidly in the second half of the century.

What you should know about this data

These projections are sensitive to the assumptions made about future fertility rates worldwide. Find out more from the UN World Population Division.

Other sources and scenarios in the UN's projections suggest that the peak was reached slightly earlier or later. However, most indicate that the world is close to "peak child" and the number of children will not increase in the coming decades.

The 'ups and downs' in this chart reflect generational effects and 'baby booms' when there are large cohorts of women of reproductive age, and high fertility rates. The timing of these transitions varies across the world.

The UN expects the global population to peak by the end of the century

When will population growth come to an end?

The UN's historical estimates and latest projections for the global population are shown in the chart.

The UN projects that the global population will peak before the end of the century - in 2086, at just over 10.4 billion people.

What you should know about this data

These projections are sensitive to the assumptions made about future fertility and mortality rates worldwide. Find out more from the UN World Population Division.

Other sources and scenarios in the UN's projections can produce a slightly earlier or later peak. Most demographers, however, expect that by the end of the century, the global population will have peaked or slowed so much that population growth will be small.

Explore data on Population Growth

Research & Writing

More Key articles on Population Growth

Hannah Ritchie and Edouard Mathieu

Hannah Ritchie, Edouard Mathieu and Lucas Rodés-Guirao

Hannah Ritchie and Edouard Mathieu

Demographic change

Definitions and sources

Other articles related to population growth

Interactive charts on Population Growth

Endnotes

1. See, for example, Kremer (1993) - Population growth and technological change: one million BC to 1990. In the Quarterly Journal of Economics, Vol. 108, No. 3, 681-716.

2. As per 2011 estimates from Carl Haub (2011), " How Many People Have Ever Lived on Earth? " Population Reference Bureau.

Cite this work

Our articles and data visualizations rely on work from many different people and organizations. When citing this topic page, please also cite the underlying data sources. This topic page can be cited as:

Hannah Ritchie, Lucas Rodés-Guirao, Edouard Mathieu, Marcel Gerber, Esteban Ortiz-Ospina, Joe Hasell and Max Roser (2023) - "Population Growth". Published online at OurWorldInData.org. Retrieved from: 'https://ourworldindata.org/population-growth' [Online Resource]

BibTeX citation

@article{owidpopulationgrowth, author = {Hannah Ritchie and Lucas Rodés-Guirao and Edouard Mathieu and Marcel Gerber and Esteban Ortiz-Ospina and Joe Hasell and Max Roser}, title = {Population Growth}, journal = {Our World in Data}, year = {2023}, note = {https://ourworldindata.org/population-growth} }

Reuse this work freely

All visualizations, data, and code produced by Our World in Data are completely open access under the Creative Commons BY license. You have the permission to use, distribute, and reproduce these in any medium, provided the source and authors are credited.

The data produced by third parties and made available by Our World in Data is subject to the license terms from the original third-party authors. We will always indicate the original source of the data in our documentation, so you should always check the license of any such third-party data before use and redistribution.

All of our charts can be embedded in any site.

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Explore global and country data on population growth, demography, and how this is changing.

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Last Stand of the Orangutan, Rapid Response Assessment | GRID-Arendal

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Assessment of the current status of Orangutan (Borneo and Sumatra) with a special focus on the national park system in Indonesia. The protected areas in Indonesia are underfunded, and the current park staff are not equipped to tackle the rampant illegal logging, hunting and burning that takes places in these areas.

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Climate change and global pollution cannot be adequately tackled without addressing the neglected issue of the world's booming population, according to two leading scientists.

Professor Chris Rapley, director of the British Antarctic Survey, and Professor John Guillebaud, vented their frustration yesterday at the fact that overpopulation had fallen off the agenda of the many organisations dedicated to saving the planet.

The scientists said dealing with the burgeoning human population of the planet was vital if real progress was to be made on the other enormous problems facing the world.

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Sharing the full story, not just the headlines

"It is the elephant in the room that nobody wants to talk about" Professor Guillebaud said. "Unless we reduce the human population humanely through family planning, nature will do it for us through violence, epidemics or starvation."

Professor Guillebaud said he decided to study the field of human reproduction more than 40 years ago specifically because of the problems he envisaged through overpopulation.

His concerns were echoed by Professor Rapley, an expert on the effects of climate change on the Antarctic, who pointed out that this year an extra 76 million people would be added to the 6.5 billion already living on Earth, which is twice as many as in 1960.

By the middle of the century, the United Nations estimates that the world population is likely to increase to more than nine billion, which is equivalent to an extra 200,000 people each day. Professor Rapley said the extra resources needed to sustain this growth in population would put immense strains on the planet's life-support system even if pollution emissions per head could be dramatically reduced.

"Although reducing human emissions to the atmosphere is undoubtedly of critical importance, as are any and all measures to reduce the human environmental 'footprint', the truth is that the contribution of each individual cannot be reduced to zero. Only the lack of the individual can bring it down to nothing," Professor Rapley says in an article for the BBC website.

"So if we believe that the size of the human 'footprint' is a serious problem - and there is much evidence for this - then a rational view would be that along with a raft of measures to reduce the footprint per person, the issue of population management must be addressed."

Professor Rapley says the explosive growth in the human population and the concomitant effects on the environment have been largely ignored by many of those concerned with climate change. "It is a bombshell of a topic, with profound and emotive issues of ethics, morality, equity and practicability," he says.

"So controversial is the subject that it has become the Cinderella of the great sustainability debate - rarely visible in public, or even in private.

"In interdisciplinary meetings addressing how the planet functions as an integrated whole, demographers and population specialists are usually notable by their absence.''

Professor Guillebaud, who co-chairs the Optimum Population Trust, said it became politically incorrect about 25 years ago to bring up family planning in discussing the environmental problems of the developing world. The world population needed to be reduced by nearly two-thirds if climate change was to be prevented and everyone on the planet was to enjoy a lifestyle similar to that of Europeans, Professor Guillebaud said.

An environmental assessment by the conservation charity WWF and the Worldwatch Institute in Washington found that humans were now exploiting about 20 per cent more renewable resources than can be replaced each year.

Professor Guillebaud said this meant it would require the natural resources equivalent to four more Planet Earths to sustain the projected 2050 population of nine billion people.

"The figures demonstrate the folly of concentrating exclusively on lifestyles and technology and ignoring human numbers in our attempts to combat global warming," he said. "We need to think about climate changers - human beings and their numbers - as well as climate change."

Some environmentalists have argued that is not human numbers that are important, but the relative use of natural resources and production of waste such as carbon dioxide emissions. They have suggested that the planet can sustain a population of nine billion people or even more provided that everyone adopts a less energy-intensive lifestyle based on renewable sources of energy rather than fossil fuels.

But Professor Guillebaud said: "We urgently need to stabilise and reduce human numbers. There is no way that a population of nine billion - the UN's medium forecast for 2050 - can meet its energy needs without unacceptable damage to the planet and a great deal of human misery."
Crowded Earth
* The human population stands at 6.5 billion and is projected to rise to more than 9 billion by 2050.

* In less than 50 years the human population has more than doubled from its 1960 level of 3 billion.

* China is the most populous country with more than 1.3 billion people. India is second with more than 1.1 billion.

* By about 2030 India is expected to exceed China with nearly 1.5 billion people.

* About one in every three people alive today is under the age of 20, which means that the population will continue to grow as more children reach sexual maturity.

* Britain's population of 60 million is forecast to grow by 7 million over the next 25 years and by at least 10 million over the next 60 years, mainly through immigration.

* This is equivalent to an extra 57 towns the size of Luton (pop 184,000)

* By the time you have finished reading this column, an estimated 100 babies have been born in the world.

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Overpopulation 'is main threat to planet'

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Climate change and global pollution cannot be adequately tackled without addressing the neglected issue of the world's booming population, according to two leading scientists. Professor Chris Rapley, director of the British Antarctic Survey, and Professor John Guillebaud, vented their frustration yesterday at the fact that overpopulation had fallen off the agenda of the many organisations dedicated to saving the planet.

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Dr. Hans W. Paerl's Illustration of the Eutrophication Cycle

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Dr. Hans W. Paerl's Illustration of the Eutrophication Cycle

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Algae grow in the sea feeding on teria which consume oxygen in this process so that the water may become temporarily anoxic ( hypoxia ) which may be toxic to aquatic life. An enrichment by or excess of nutrients to the water is called nutrients in the water. Algae grow better when more nutrients (nitrates and phosphates) are present in the water column . A small increase in algal biomass has no adverse effects on the ecosystem and can even lead to an increase of certain fish populations . An overgrowth however can lead to an The algae may keep out the light and when they eventually die, they are decomposed by bac eutrophication and may result in an explosive growth of algae. D epending on the environment (quiet bay or rough seas) and the type of algae (microsco algal bloom which may disturb the water. pic or macroscopic), a 'bloom' can be observed in different forms: foam or a green tide on the beach.

Foam on the beach due to a Phaeocystis bloom (Le Portel France: 04/2012)
(Photo credit: Nausicaa, Adrien Delater-Julien Legrand)

Green algae on the beach (Nord Finistère, Brittany-France)
(Photo credit: Thesupermat, Wikipedia)

Eutrophication is one of the causes of the deterioration of water quality. In the North Sea and the English Channel, this is mainly due to human activities. Nutrients can have a natural or anthropogenic origin and come from:

Domestic wastewater

Industrial waste

Agriculture (fertilizer use)Atmos pheric deposition of nitrogen (livestock and gases)

Increasing biomass of phytoplankton resulting in 'algal blooms'.

Hypoxia (reduced dissolved oxygen content of a body of water).

An increasing number of incidents of fish kills.

The water can have a bad taste, color and odeur which has a negative impact on tourism. Governments have to invest more in waste water treatment.

Decline or loss of species biodiversity (commercially important species may disappear).

Some phytoplankton species produce toxins that cause severe symptoms such as diarrhea, memory loss, paralysis and in severe causes death.

Schematic diagram of the different pathways of nutrient deposition into coastal waters and ensuing processes leading to eutrophication (algal blooms) and hypoxia (Photo credit: Dr. Hans W. Paerl)

Such environmental problems have not only an effect on aquatic life, but can also have a negative impact on the economic activities of the sea (fishing, tourism, recreation ...). Past 20 years, all these issues have been extensively studied and have been the subject of many discussions ... The problem has been addressed in the Water Framework Directive and the European Union within the OSPAR Convention in 1992. Both agreements aim to establish a good management of our rivers and our coastal waters. To achieve these objectives, the parameters of water quality should be regularly monitored and published. Similarly, we must study the socio-economic effects on the areas subject to eutrophication and identify the necessary information to stakeholders (political, agricultural, industrial, tourism ...).

Need more information? Go to the WIKIPAGE

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Algae grow in the sea feeding on teria which consume oxygen in this process so that the water may become temporarily anoxic ( hypoxia ) which may be toxic to aquatic life. An enrichment by or excess of nutrients to the water is called nutrients in the water.

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Causes of eutrophication

In general, the nutrient elements limiting the primary production in freshwater is phosphorus (mainly phosphate) while that in the marine environments is nitrogen (mainly nitrate). In the marine environment, exceptions have been reported to this general rule. Thus the eastern Mediterranean Sea and many eutrophied estuaries are P rather than N limited, while the equatorial Pacific and extensive regions around Antarctica appear to be Fe-limited. What are the sources of nutrients to aquatic ecosystems? There is nutrient supply from

agriculture and husbandry,

aquaculture and factories,

sewage from towns, river run-off and erosion,

atmospheric deposition,

nitrogen fixation.

28% of the annual N fixation of the global biosphere is caused by nitrogen fertilizer production, which is energetically expensive and largely based on fossil fuel consumption. A three-fold increase in N utilization by agriculture in Western Europe and USA has been recorded between 1950 and 1970 on agricultural land that actually declines because increased efficiency or over-exploitation (Figure 2). Animal waste from intensive husbandry is of particular significance for nutrient point sources: considerable amounts are directly supplied to freshwater and fields. There are also significant losses by NH ₃ emission and denitrification on fields, rivers or shallow estuaries, connecting the agricultural lands directly to the atmosphere. Agricultural run-off has given rise to significant eutrophication in most estuaries, but also in entire coastal seas such as the southern North Sea, Baltic Sea, Kattegat, northern Adriatic Sea, Chesapeake Bay and Seto Inland Sea in Japan.

Figure: Annual global nitrogen fertilizer consumption for 1960-1995 (1 Tg = 10 ¹² g; data from FAO 1999). The rate of increase was relatively steady until the late 1980s, when the collapse of the Soviet Union reduced fertilizer use in Russia and former Soviet republics. Fertilizer use is growing again, driven in large part by use in China (modified from Matson et al.[] and Anonymous[]).

Aquaculture techniques are applied to restricted areas such as straights, fjords and rias where it, in the worst case, may induce anoxia (if hydrodynamic energy supply is insufficient). C and N supply is normally regulated by environmental control, but can be detrimental in some areas. It has been reported that accumulation rates of fat- and N-rich food and faeces at the bottom below caged fish production sites could make up to 10 cm per month! As much as 30 and 40% of the annual discharge of P and N, respectively, is caused by aquaculture in some fjords. Unless an entire region is used for aquaculture, it has `local' consequences for both plankton and benthos. However, large factories of the food industry can discharge significant amount of dissolved and particulate organic matter as well as nutrients into the recipient that can represent important point sources.

Close to cities and dense populated areas sewage is of utmost significance, but compared to run-off from agricultural drainage basins, point sources are of less significance; see also agricultural runoff section). The emphasis given to sewage treatment in many regions is in contrast to the inefficient and at time completely lacking emphasis on the largest nutrient source for aquatic recipients, i.e. the agriculture. Sewage discharge has `local' consequences, although local could mean entire estuaries, river mouths and fjords. The frequent removal of P by sewage plants and the decline of utilization of P fertilizers (in contradiction to N, Figure 3) results often in an excess supply of N. Consequently, marine recipients are forced into P rather than N limitation. Far more emphasis has been given to sewage treatment than manipulations of effluents from agriculture, and this can be partly explained by the relative simplicity of removing nutrients from point sources.

Figure: U.S. commercial fertilizer use (modified from Evans et al. [] and Anonymous[]).

River-run off has changed significantly over the last 200 years in many region of the world. Large-scale manipulation of lower reaches of river has resulted in greater river speeds. The residence times of water in the Rhine river water shed was far greater before 1850 when it was so shallow and meandering south of the town of Strasbourg that one could walk through it even during flood times! Extensive wetlands have been removed in favour of shipping and straightforward navigation. Both agriculture and logging result in increased erosion as trees, bushes and vegetation is reduced. Removal of wetlands for agricultural purposes results in decreasing self-purification as denitrification decreases. As a consequence, we experience an increased contribution of particulate matter and nutrients to estuaries. Due to various practices, N supply to marine waters does still increase in Western Europe, while P supply decreases (Figure 3). As a consequence P limitation in eutrophicated coastal regions increases.

Lately, more focus has been given to the role of the atmosphere affecting the availability of nutrients in aquatic ecosystems (see atmospheric deposition section). Generally, nutrient supply from the atmosphere is in the form of N. Only in case dust is deposited particulate P is deposited atmospherically. Atmospheric deposition of nutrients is partly due to fossil energy application, leading to the emission of NO x gasses to the atmosphere. Here these gasses are transformed to nutrients such as NO ₃ that can be deposited as wet or dry deposition. However, much of the atmospheric nutrient deposition comes from the emission of NH ₄ by intensive husbandry and meat production. The annual atmospheric supply of N to open Skagerrak is more than 30% of N the budget! It is relatively lower in the winter months when run-off from land is prominent, but can be the dominating N source during summer. Atmospheric N deposition is closely reflected to source regions, the movements of air masses and the low-pressure pathways. Atmospheric deposition of N gives rise to a wide spread eutrophication of freshwater and terrestrial environments as well as the sea. Eutrophication due to use of fossil energy depends on emission and precipitation pattern.

During nutrient limiting conditions N fixation can be an important source of N in fresh water and brackish water bodies such as the Baltic Sea. The significance of N fixation is still a matter of discussion in marine environments. However, the global N ₂ cycle has changed greatly due to the production of fertilizers as human N ₂ fixation is now in the same order of magnitude than the calculated global fixation.

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Eutrophication -- Causes of eutrophication

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In general, the nutrient elements limiting the primary production in freshwater is phosphorus (mainly phosphate) while that in the marine environments is nitrogen (mainly nitrate). In the marine environment, exceptions have been reported to this general rule.

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Landfills and Water Quality Management by G. Fred Lee

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Landfills and Water Quality Management by G. Fred Lee

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Reprinted from Transactions Northeast Fish and Wildlife Conference May 1972 p. 39-60

EUTROPHICATION

G. Fred Lee
Institute for Environmental Sciences
The University of Texas at Dallas
P.O. Box 688
Richardson, Texas 75080

ABSTRACT

The eutrophication-excessive fertilization of natural waters is becoming one of the most important causes of water quality deterioration. The cultural activities of man greatly accelerate the transport of phosphorus, nitrogen and other elements which may limit aquatic plant growth in natural waters. These nutrients stimulate the growth of floating or suspended algae, attached algae and macrophytes. Excessive growths of these aquatic plants result in a significant deterioration in water quality for the use of the water for domestic and industrial water supplies, irrigation and recreation.

The control of eutrophication is normally based on limiting aquatic plant nutrient input. Such control efforts must be directed toward the element which is currently limiting or can be made to limit algal growth in the body of water of concern. Domestic wastewaters represent potentially significant sources of nitrogen and phosphorus for the excessive fertilization of surface waters. Eutrophication control efforts are generally directed toward limiting the phosphorus content of domestic wastewaters by precipitation or co-precipitation treatment methods involving the use of aluminum or iron salts or lime. Other potentially significant sources of nitrogen and phosphorus include urban and rural stormwater drainage and atmospheric inputs. One of the most important sources of phosphorus in the upper Midwest is the manure spread on frozen soil from dairy farming and feedlot operations. The control of nitrogen and phosphorus from urban and rural diffuse sources is a much more difficult task and will require the expenditure of large amounts of funds if excessive fertilization of natural waters it to be minimized to the greatest possible extent.

The fertilization of natural waters may result in the production of excessive growths of algae and higher plants. These crops may cause a serious deterioration of water quantity. Today, the excessive fertilization (eutrophication) of natural waters is one of the most significant causes of water quality problems in North America. It is likely that as other sources of pollution are abated, the problems of excessive fertilization will assume a greater role in the deterioration of aquatic environmental quality. Eutrophication problems are not restricted to lakes; they also occur in rivers, impoundments, estuaries and other coastal waters.

This paper discusses the general aspects of the eutrophication of natural waters. Emphasis is placed on methods of measuring eutrophication, on the causes of eutrophication (particularly the sources of aquatic plant nutrients and the factors that influence aquatic plant production), on the effects of eutrophication on water quality and oil methods of controlling or reducing the rate of eutrophication. Additional information on these topics can be obtained in the following papers and reviews: Anonymous (1961), Edmonson (1968), Frey (1963), Hasler (1947), Hutchinson (1957, 1967), Jackson (1964, 1968), Lee and Fruh (1966), Machenthun (1962), Machenthun and Ingram (1967), Machenthun et al. 1964), National Academy of Science (1969), National Technical Advisory Committee (1968), Sawyer (1966), Stewart and Rohlich (1967), Veatch and Humphrys (1964) and Vollenweider (1968).

CLASSIFICATION OF LAKES

Lakes and other surface waters are frequently divided into one of two types, oligotrophic and eutrophic. Although the exact meaning of these two terms depends on the user, it is generally agreed that oligotrophic lakes are relatively unproductive and receive small amounts of aquatic plant nutrients, while eutrophic lakes are highly productive and experience high fluxes of aquatic plant nutrients.

The problem of defining these terms, oligotrophic and eutrophic, is related to the fact that some aquatic scientists use them to refer only to the flux of aquatic plant nutrients, while others use them to describe the amounts of plant and/or animal production. Still others use them to relate nutrient flux to water quality. In reality, with few exceptions, the various definitions all are essentially the same since high nutrient fluxes result in higher plant and animal production and decreased water quality.

Table I. General Characteristics Frequently Used to Classify Lakes

Table I summarizes the general characteristics of oligotrophic and eutrophic lakes. Oligotrophic lakes contain small amounts of organisms but many different species of aquatic plants and animals. Eutrophic lakes are generally thought to contain large numbers of aquatic plants and animals of a few species. Recent evidence seems to indicate that eutrophic lakes may contain as many different species as oligotrophic lakes. The difference between the two is primarily that in eutrophic lakes there tends to be one or two species that dominate the population. Normally, lakes that are sufficiently deep to develop a thermocline (two-layer system due to density differences as a result of the thermal structure) and show a partial or complete depletion of dissolved oxygen in the hypolimnion (bottom layer) are classified as eutrophic, while those that maintain the oxygen in the hypolimnion throughout the period of thermal stratification are oligotrophic. T his oxygen depletion in the bottom waters of a lake is dependent on amounts of aquatic plants that develop in the surface water and the morphology of the lake. For lakes with a given amount of aquatic plant production in the epilimnion (surface layer), those with a large hypolimnetic volume tend to have the oxygen concentration depleted to a lesser degree than those with a smal hypolimnetic volume. With few exceptions, the amount of aquatic plants produced in a lake is restricted to the surface waters since light penetration is usually restricted to epilimnetic waters.

In addition to differences in the total amounts of aquatic plant and animal production and the numbers of types (species) of each, the two types of lakes vary as to the type of organisms produced. Although no indicator species have been found that are only present in one type of lake, it is generally observed that eutrophic lakes have greater numbers of blue-green algae and rough fish such as carp. At times, statements appear in the popular press that a eutrophic lake, like Lake Erie, is dead. Actually, this is exactly opposite to the real situation in that eutrophic lakes suffer from problems due to excessive amounts of life of all forms. The fertilization of a body of water increases all forms of life from the planktonic (freely suspended) algae, attached algae and rooted higher plants that develop in nearshore water to the zooplanklon, benthic organisms and fish.

Oligotrophic lakes arc usually deeper than eutrophic lakes. However, this characteristic is highly variable and it is probably best to state that shallow lakes are frequently eutrophic and that as an oligotrophic lake fills due to deposition of sediments, it will become more eutrophic.

Another characteristic that is sometimes used to classify lakes is the total dissolved salt content or specific conductivity The use of this parameter is based on an empirical correlation between the general levels of plant and animal production and total dissolved salts. Frequently lakes with higher dissolved salts tend to be more productive. Beeton (1965) has presented as evidence for the eutrophication of the St. Lawrence Great Lakes an increase in the dissolved salt content of these waters. Chemical species that make up the bulk of the total salts in most lakes are calcium (Ca⁺⁺), magnesium (Mg⁺⁺), sodium (N a⁺), potassium (K⁺), sulfate (SO ₄=), bicarbonate (HCO ₃-) and chloride (Cl⁻). Sometimes nitrate (NO ₃-) concentrations are encountered in ground waters in amounts that contribute to the dissolved salts or specific conductance of the water. With the exception of nitrate, all of these species play minor roles in aquatic plant production of a lake. i.e., their concentrations are in sufficient excess so that they do not limit the plant production. Therefore, high total salts in a lake usually mean that the lake also has a high content of aquatic plant nutrients.

In the case of the St. Lawrence Great Lakes, the increase in dissolved salts with time observed by Beeton was the result of a greater degree of cultural activity in the lakes' drainage basins and thus an increased flux of many of the common cations and anions normally found in lakes. As will be shown later, associated with the increase in cultural activity, a higher nitrogen and phosphorus flux will also occur. Although the total amounts of nitrogen, phosphorus and other aquatic plant nutrients are insufficient to be determined as a part of the dissolved salts or specific conductivity, they are sufficient to cause excessive growths of algae and other aquatic plants in Lake Erie and parts of the Great Lakes. Even though these salts probably do not significantly contribute to the nutrients for aquatic plants, their buildup in the Great Lakes is of major concern and will require their removal from some waste waters in the foreseeable future.

Limnologists use many other terms to classify lakes, such as dystrophic, mesotrophic, hypereutrophic, etc. Some of these terms bear little or no relationship to the nutrient flux, while others do (i.e., they are subdivisions of the oligotrophic-eutrophic classification). For the purposes of this discussion, oligotrophic and eutrophic classification is adequate to describe the relationship between nutrient flux and water quality problems.

CLASSIFICATION OF EUTROPHICATION

Once a lake has been found to be eutrophic, it is further classified as to the process by which the eutrophication took place. Some lakes and other surface waters are naturally eutrophic, i. e., they receive sufficient aquatic plant nutrients from natural sources to produce excessive crops of algae and macrophytes. Many references in the literature state that lakes start as infertile bodies of water, with time accumulate nutrients, become more fertile, eventually fill with sediments and become a marsh and then dry land (Hasler, 1947). However, studies on the chemical characteristics and organism remains in lake sediment cores indicate that lakes do not become more fertile with time. In fact, it is likely that lakes are highly fertile immediately after formation and may lose this fertility as the easily leachable nutrients are removed from the watershed.

Regardless of whether these lakes become more or less fertile with time, natural eutrophication accelerates when a lake becomes shallow enough due to sediment accumulation so that it loses its permanent stratification. At this point, nutrients are no longer trapped below the thermocline, and the lake becomes more fertile since its nutrients are more rapidly recycled from its sediments. A final major transformation in the natural eutrophication of a lake is the point where the lake is sufficiently shallow so that macrophytes occupy a major part of the lake basin. At this point in time, the lake starts to fill at a markedly different rate due to partial degradation of higher aquatic plant remains. Whether the natural eutrophication of lakes follows the sigmoid growth curve or proceeds in a stepwise manner, as proposed here, will await further research (see Figure 1).

It might be argued that the shape of the natural eutrophication curve should have a step in it to correspond to the time that the hypolimnetic waters of the lake become anoxic to any significant degree. While it is clear that deoxygenation of the hypolimnion does lead to and cause large releases of many aquatic plant nutrients such as nitrogen and phosphorus, it is doubtful that this release plays an important role in fertilizing the lake during the critical use period of the summer. The thermocline appears to be a very effective barrier to the transport of nutrients from deeper sediments of lakes to the overlying water. Fall overturn or mixing in the lake does result in the mixing of high-nutrient hypolimnetic waters with the epilimnetic waters. Often this will result in an algal bloom. Normally, by this time of year the water has cooled sufficiently so that the algae that cause the severe summer blooms (blue-greens) do not develop. Although the fall blooms can cause serious water quality problems from a water supply use point of view, these blooms rarely cause serious recreational use problems because the waters generally are not used as intensively in the fall as in the summer.

The high nutrient level that develops at the beginning of fall overturn rarely persists for any period of time since the fall algal blooms tend to carry the nutrients to the sediments and, more importantly, the ferrous iron that was present in the hypolimnion is oxidized to ferric iron by dissolved oxygen and precipitates as ferric hydroxide, carrying with it coprecipitated and occluded phosphorus to the sediments. Based on the current degree of understanding of the aqueous environmental chemistry of phosphorus, it is unlikely that the aquatic plant nutrients brought to the surface waters at this time play a major role in increasing the degree of eutrophication of a lake, and therefore no provision has been made to include a step in this natural eutrophication diagram to reflect the time in a lake's history that the hypolimnion becomes anoxic to a significant degree. It should be pointed out that research in systems models of the water chemistry of plant nutrients will likely produce changes in the shape of this diagram.

While these lakes become naturally eutrophic in the absence of man, other lakes are culturally eutrophic, i. e., they receive aquatic plant nutrients from artificial sources or, more specifically, as a result of man's presence. The activities of man in a lake's watershed can bring about the cultural eutrophication of a lake in a period of a few years, whereas natural eutrophication is a very slow process and is estimated as occurring over hundreds to thousands of years. Because of this marked difference in the normal relative rates of cultural versus natural eutrophication, it is likely that any measurable change in the tropic state of a lake in the past 50 years is due to cultural rather than natural causes.

CAUSES OF EUTROPHICATION

A great variety of influences contribute to the eutrophication of a water. These are discussed as a background to considering the effects of eutrophication and means of reducing them.

FACTORS THAT INFLUENCE AQUATIC PLANT PRODUCTION

The productivity of a given body of water is dependent on solar radiation, temperature (to some degree) morphology and the concentration of aquatic plant nutrients present in water and/or available to organisms.

Aquatic plant production is apparently not inhibited by cold temperatures since excessive algal populations are found in waters near the freezing point. Frequently, very high concentrations of blue-green algae will be found in temperate lakes growing under a meter or more of ice, although some of the more objectionable forms of algae such as the blue-greens are generally considered warm-water organisms.

The discharge of waste heat from large electric generation stations such as nuclear power plants is often alleged to cause an increased eutrophication of a lake. While it is true that blue-green algae tend to be more prevalent in warm waters, there is no reason to believe that the total biomass of the organism would change significantly as a result of heating the water a few degrees above ambient. Normally, the biomass of a certain type of algae during a season is dependent on availability of aquatic plant nutrients rather than on factors such as temperature. There is serious doubt that the highly localized heating of water resulting from large nuclear-power electric generating stations located on large lakes should have an effect on the over-all degree of eutrophication of the take as a whole. It is possible that, where suitable substrates for the attached algae exist in the region of the discharge plume of the electric generating station, these forms might develop a little earlier each spring and persist slightly longer each fall. However, it is doubtful that the total amounts of these organisms would be increased during the critical recreational use during summer months.

The amounts of planktonic algae would not be expected to increase due to discharge of waste heat to large lakes since their rate of growth is normally much slower than the time they would be exposed to elevated temperatures in most electric generating station thermal plumes.

Light does limit the aquatic plant production in waters which have large amounts of suspended solids that increase turbidity or have high color. Normally, lakes of this type are very shallow and are subject to strong mixing by wind or animals such as fish or receive large amounts of marsh or swamp drainage.

The role of morphology of a lake in deter mining its productivity is discussed under a subsequent topic.

Of factors thus far considered, if light, temperature, basin morphology and residence time of water are "normal," a sufficiently high flux of aquatic plant nutrients can create eutrophication problems. Even if these other factors are not "normal," i. e., they are operating to increase aquatic plant production. This production is still most frequently controlled by the flux of chemical compounds that influence algal growth. Although the nutritional requirements of algae and higher aquatic plants are poorly understood, it is generally agreed that they all have large requirements for carbon (C), nitrogen (N), hydrogen (H), oxygen (O), and phosphorus (P) and need lesser amounts of many different trace elements (Anonymous, 1967; Fogg, 1965; Goldman, 1966; Irwin, 1962; Machenthun, 1965; Machenthun and Ingram, 1966; Middlebrooks et al., 1969; Vollenweider, 1969). The nutrient requirements of aquatic plants are much the same as those of terrestrial plants except for the need for potassium by terrestrial plants. The fixation of potassium by clay minerals causes a deficiency in soils, while in water there is generally sufficient potassium to meet the needs of the aquatic plants. Aquatic plants are different in one important respect from some terrestrial plants in that they can use either NO ₃- or NH ₄+ with about equal facility, while some terrestrial plants are reported to use only NO ₃-. Some algae will take up NH ₄+ in preference to NO ₃-. Some of the blue-green algae also have the ability to use N ₂ gas. Since the dissolved N ₂ content of water is always high, the process of N ₂ fixation gives this group of algae the ability to grow at very low NO ₃- and NH ₄+ concentrations. Orthophosphate (PO ₄) is the form of phosphorus that is readily available for algal growth although it is possible that other forms such as P-O-P and organic phosphorus may also be available to algae. The role of these compounds in the growth of algae is discussed under a subsequent topic.

TYPES OF AQUATIC PLANT NUTRIENTS

The aquatic plant nutrients often considered to be the most significant ones limiting the growth of aquatic plants in surface waters are orthophosphate, nitrate, nitrite and ammonia. Other species of phosphorus and nitrogen, such as the organic forms, can and do contribute to the fertility of the water, either directly through uptake by the organisms or indirectly through their conversion to the other previously mentioned forms by abiotic and biotic chemical reactions.

There are some who feel that carbon should be listed as one of the critical elements in terms of the fertilization of natural waters. However, evidence to date seems to indicate that carbon (in the form, CO ₂) becomes limiting only in the presence of excessive or massive blooms of algae and that under these conditions the degree of eutrophication is exceedingly high. At that time, water quality has deteriorated to such a degree that further plant production is of limited consequence.

With regard to the trace elements, it is known that some are essential for growth of plants; for example, the diatoms need silica for growth. However, even with the diatoms, silica is generally not a limiting element, but is in excess 6f what is needed for the production of large numbers of these organisms.

Probably the next most frequently mentioned element that could possibly limit or control the populations of algae in lakes is iron. Iron is present in the epilimnion of lakes in the ferric form; in this state of oxidation, it is extremely insoluble as a hydrous oxide and is rapidly precipitated and transmitted to the sediments of the lake. Since some investigators have found an apparent iron deficiency in some waters, iron may indeed be an element limiting plant growth.

Other elements that are mentioned as essential for growth of algae and other aquatic plants include sulfur, potassium, magnesium, calcium, boron, zinc, copper, molybdenum, manganese, cobalt, sodium and chlorine. Regarding these elements and various organic components of water such as vitamins, hormones and chelating agents, the question must hr asked do they control (i.e., limit) algal growth or are they simply essential and in sufficient concentrations to provide for excessive crops of aquatic plants?

It is fair to state that nitrogen and phosphorus are probably the key elements in controlling aquatic plant growths and that the other elements, compounds and components of water may be important under certain conditions in certain types of waters. Further research will be necessary to fully delineate their roles in the eutrophication of natural waters.

CONCENTRATIONS AND SOURCES OF NITROGEN AND PHOSPHORUS

Since nitrogen and phosphorus appear to be the most important plant nutrients, the question may be asked: what are the critical concentrations of these two nutrients in most natural waters? This is a topic of great concern today in terms of attempting to manage the nutrient input to lakes. If the nutrient input can be limited so that the total concentrations in the lake are less than the critical concentrations, beyond which eutrophication will occur, then it would be possible to control the degree of eutrophication of the water. Although few studies have been made, reports by Sawyer et al. (1945) and Vollenweider (1961) pertaining to Wisconsin lakes and Swiss lakes, respectively, indicate that when the inorganic nitrogen content (ammonia plus nitrate nitrogen) is equal to or greater than 0.3 milligram per liter of nitrogen and the orthophosphate content is equal to or greater than 0.01 milligram per liter of phosphorus, then the lake is likely to have excessive crops of algae and other aquatic plants. These numbers represent, to some degree, the best estimates available today of the critical concentrations of these elements.

Unfortunately, the relationship between these concentrations and aquatic growth is a complicated one and the use of these concentrations to predict or prevent the eutrophication of a given body of water is difficult for the following reasons:

1. The productivity of a given body of water, as pointed out previously, depends on other factors in addition to the concentrations of nutrients. For example, the species of algae and other aquatic plants are determined not only by the amounts of, but also by the ratios between, the various elements.

2. Even if productivity were controlled only by nutrient concentrations, it is not certain at the present time whether nitrogen and/or phosphorus is (are) the controlling element(s). The evidence obtained in the past few years seems to show that nitrogen controls a certain population at certain times during the year while phosphorus in the same lakes may be controlling another population at another time.

3. The critical concentrations proposed by Sawyer and Vollenweider are based on excessive growths of algae as the quality criteria. While these concentrations might be used to predict one kind of eutrophication (caused by excessive plant growths), they overlook those water quality problems produced by much lower concentrations of nutrients. Specific forms of algae, for example, are known to cause taste and odors in water supplies or to produce clogging in sand filters in water treatment plants.

4. The stoichiometric concentrations of some of the primary elements in algae vary within fairly wide limits. Both fresh-water and marine algae contain, on the average, 106 carbon atoms for each 1 phosphorus and 16 nitrogen atoms. Algae, though, have the ability to store what is termed surplus phosphorus which ranges from five to approaching 10 times the minimum requirements for the particular cell. The composition of algae is therefore highly variable and dependent on the composition of water.

5. Furthermore, some algae have specific phosphorus and/or nitrogen requirements which are markedly different from those of other algae. Phosphorus levels which are greatly below the critical concentrations found by Sawyer may be sufficient to support the growth of some algae, yet Sawyer's critical concentrations of phosphorus might actually be toxic to these same algae.

6. Finally, attempts have been made to use the critical concentrations to "limit" the phosphorus content of a given body of water. Such attempts, recently tried by both federal and state governments, do not, however, take into account the complex aqueous environmental chemistry of phosphorus. Trying to control the nutrient input for a given lake, so that its phosphorus levels are kept below Sawyer's critical concentrations, ignores the fact that the sediments of a lake act as a sink and source for many of the nutrient elements. Thus, input control may not limit the actual phosphorus concentrations to a lake because of the rate at which this element is transferred from the sediments to the water. The role of sediments in supplying nutrients to the overlying waters is discussed under a subsequent topic.

References cited under "Factors That Influence Aquatic Plant Production" should be consulted for additional information on the nutritional requirements of algae and other aquatic plants. With this background, it is appropriate to examine the various sources of nitrogen and phosphorus compounds in an attempt to gain some insight into the potential causes of water-quality problems doe to excessive fertilization. Additional information may be obtained from references: Anonymous (1967, 1969), Lee (1966) and Weibel et al. (1964).

DOMESTIC WASTE WATERS

One of the foremost sources of nitrogen and phosphorus in natural waters is domestic waste waters. Domestic waste waters often contain tens of milligrams per liter of nitrogen and from 5 to 20 milligrams per liter of phosphorus . The concentrations of nitrogen and phosphorus in domestic waste waters are highly variable and are dependent on the time of day and day of the week. If these concentrations are compared to the critical concentrations, it is readily apparent that domestic waste waters must be diluted manyfold in order to reduce the fertilizing potential below those levels cited by Sawyer as critical concentrations.

Of major concern today are the sources of phosphorus in domestic waste waters. Several studies have shown that approximately 50 per cent of the phosphorus present in domestic waste waters is derived from the phosphorus that is used in various cleaning compounds such as detergents. Many detergent formulations contain condensed phosphates which have been shown to hydrolyze to orthophosphate during domestic waste water treatment or in natural waters. Some attempts are being made today to try to limit the amounts of phosphates used in detergents to reduce the fertilizing potential of domestic waste waters.

A crude estimate of the amounts of nitrogen and phosphorus contributed by domestic waste waters can be made in terms of a population equivalent. Various studies have shown that 2 to 3 pounds per person per year of phosphorus and 7 pounds per person per year of nitrogen are contributed to typical domestic waste waters. These figures, then, can be used to obtain crude estimates of the potential significance of a given waste water in terms of its nitrogen and phosphorus contribution to a watercourse.

Eutrophication problems may also result from sludge disposal associated with waste water treatment. Sludge and other solids are usually placed on the ground or in a pit, and garbage is frequently disposed of on low lands which have high water tables. Nutrients from these areas can be carried into the ground water and, during periods of heavy rains, into surface waters via runoff. High nitrogen and phosphorus content waters are associated with both domestic wastewater sludge disposal and garbage and refuse disposal areas.

The individual household septic tank disposal system may also contribute nutrients to surface waters. In general, nitrogen is readily transported in ground waters, and, therefore, a significant part of the nitrogen going to septic tank systems will be transported to the ground water if it is oxidized to nitrate and does not become denitrified. Phosphate is usually strongly sorbed by aquifer materials except in sandy areas. Quartz and other sands that have low iron, carbonate. aluminum, clay mineral and organic content will readily transport phosphate in ground waters. In nonsandy soils, septic tanks frequently fail in a short period of time due to the plugging of the tile field. When this occurs, surface discharge results and nutrients are transported via overland flow to the nearby watercourse.

INDUSTRIAL WASTE WATERS

Industrial waste waters can have very large or very small amounts of aquatic plant nutrients. For example, some waste waters which cause serious; water-quality problems, such as waste water from pulp and paper plants, obtain relatively small amounts of nitrogen and phosphorus, but large amounts of carbon. However, waste waters, such as those associated with phosphate mining, do contribute large amounts of phosphorus to the water. The nutrient content of industrial waste waters may or may not be serious and varies front industry to industry.

URBAN DRAINAGE

Runoff from urban areas is beginning to be recognized as an important source of aquatic plant nutrients. Frequently, stormwater runoff contains a few milligrams per liter of nitrogen and phosphorus. Weibel et al.(1964) found that in Cincinnati approximately 9 pounds per acre per year of nitrogen and 0.8 pound per acre per year of soluble phosphorus are contributed in stormwater runoff. At this time, little information is available on the sources of these high concentrations in streets, although fertilizers used on lawns, normal dust fall, leaves, waste materials from domestic pets, gasoline automobile engines and other, combustion processes must be considered as possible sources. Further research, though, will be necessary to delineate the relative significance of these sources.

AGRICULTURAL DRAINAGE

Because of the fact that large quantities of fertilizers are often used on various crops, agricultural drainage is often thought to be a significant source of nutrients for surface waters. Although under proper soil, water and fertilizer management, it is possible to control the amounts of nitrogen and phosphorus derived from fertilizers applied to croplands, misapplication of these materials can result in large amounts being carried to surface waters. Studies of farmlands located near Madison, Wisconsin, have shown that the nutrient content of farmland drainage can range from that essentially associated with natural sources, with concentrations on the order of 0.03 and 0.003 pound per acre per year of nitrogen and phosphorus, respectively, to values many times this amount where applied fertilizers are used in great excess of their needs or where conditions tend to promote their runoff to the nearby surface waters.

One of the most significant sources of nutrients in the agricultural drainage for the area near Madison, Wisconsin, is the manure derived from dairy farm operations. In this part of the country, dairy farmers maintain approximately 100 cows per square mile, each cow producing 15 tons of manure per year. When this manure is spread on the land during late spring, summer and early fall, it is reasonable to expect that the nutrients present in the manure will be carried into the soil and, in general, will become associated with the crops that develop. However, during the winter period the manure spread on the land cannot leach its nutrients to the frozen soil. At the time of spring thaw and rain, the snow melt and rainwater combine in a heavy overland flow, carrying with it the nutrients from the manure spread on frozen land.

In general, the manure problem associated with dairy operations is small compared to the manure problems found on animal feedlots where the density of animals is much higher. Feedlots often have animal densities approaching 50 to 100 animals per acre, and some lots contain as many as 100,000 animals. Drainage from these large feedlots requires treatment similar to the treatment needed for domestic waste waters.

In the western United States, the irrigation return waters have high concentrations of nitrogen which may cause eutrophication problems. Some irrigation return waters have been found to contain concentrations of nitrate approaching 50 milligrams per liter of nitrogen. These waters require treatment to remove the very high concentrations of nitrogen.

NATURAL SOURCES

Many lakes are naturally eutrophic, i.e., they receive large enough quantities of nitrogen, phosphorus and other plant nutrients to produce excessive crops of aquatic plants. Under these conditions, the watershed of the lake serves as the nutrient source and will supply the lake with large amounts of nitrogen and phosphorus. Some soils, such as many of those located in the Midwest, are highly fertile and contain large amounts of nitrogen and phosphorus, with the result that small lakes which receive drainage from large land areas are often naturally eutrophic.

LAKE SEDIMENTS

Sediments of a lake often contain thousands of parts per million (millograms per kilogram dry weight) of phosphorus and nitrogen. If the sediments are mixed with the water and contain leachable nutrients, potentially very small amounts of sediments could fertilize large quantities of water. Fortunately, however, most of the nitrogen and phosphorus present in lake sediments are bound in refractory (nonleachable) forms.

Recent studies have shown that some lake sediments can act as phosphate buffers. If the phosphorus concentration in the overlying waters is decreased, the sediments will contribute phosphorus to the overlying waters to make up for this decrease. Sediments will also contribute nitrogen to overlying waters, although nitrogen appears. to be controlled more by the aerobic and anaerobic conditions (Lee, 1970). Further studies on the role of lake sediments as a source of nitrogen and phosphorus for lakes are urgently needed. Recently-completed studies on the rates of recovery of lakes upon a nutrient to phosphate input reduction have shown that the sediments of the lakes do not significantly affect the lake's recovery rate.

ATMOSPHERIC SOURCES

Precipitation in the form of rainfall and snowfall is a significant source of nitrogen in some parts of the world. In the Midwest, typical rainfall contains on the order of 1 milligram per liter of nitrate nitrogen. When this is compared to the normal 0.3 milligram per liter often cited as the critical concentration of nitrogen, rainfall rather than diluting the nutrients in a lake is actually contributing to them. Phosphorus is fairly low in most rainfall, although some recent data indicate that lakes in some parts of the United States receive significant amounts of phosphorus from atmospheric sources in the form of precipitation and dust fall.

GROUND WATER

Ground water rarely contains significant concentrations of phosphorus since phosphorus species tend to be strongly sorbed on aquifer materials. But ground waters can contain large concentrations of nitrate nitrogen since nitrate is very poorly sorbed by most aquifer materials. It is not uncommon to find that nitrate nitrogen is present in ground waters at 1 milligram per liter of nitrogen. In some situations, this concentration can reach 40 to 50 milligrams per liter. Ammonia nitrogen and various phosphate species tend to he sorbed in most clay soils. However, in sandy soils, such as those frequently encountered around glacial lakes, it may be found that the sorption capacity of sand is exceedingly small with the result that septic tank disposal systems located adjacent to a lake in a sandy soil rarely have problems of plugging. However, these systems also readily transmit the nutrients from the household to the nearby watercourse via ground water.

A special but frequent cause of ground contamination is sanitary landfills and other solid-waste, garbage, refuse and sludge disposal systems. Community waste-solid materials and wastewater sludges are deposited on lowlying land, frequently wetland areas. Recent studies have shown that serious ground water contamination problems have resulted from such practices. Other solid-waste and wastewater-sludge disposal systems must be initiated in order to avoid ground water contamination from various types of aquatic plant nutrients.

MARSHES

In general, marshy areas contain large populations of aquatic plants. It is reasonable to expect that these areas would act as nutrient traps and remove nutrients from inflowing waters during the growing season. However, during the winter and spring period in cold climates, marshes discharge large quantities of nitrogen and phosphorus, and in so doing probably act on a short-term basis to delay until times of high spring flow the outflow of nutrients. Therefore, it is reasonable to question whether or not a marsh is a nutrient trap over an annual cycle.

The drainage and conversion of marshes into either urban or agricultural areas can result in a significant release of nitrogen species, particularly nitrate. The marsh environment is typically an anaerobic one in which the nitrogen is present in the form of organic nitrogen and ammonia, both of which tend to remain associated with soil particles and plant debris within the marsh. However, draining a marsh converts it from an anaerobic to an aerobic environment which promotes biochemical conversion of organic nitrogen to ammonia and the conversion of ammonia to nitrate. Nitrate is highly soluble in water, poorly sorbed by soil particles and rapidly transported from the marsh systems The drainage of a marsh is likely to result in a significant increase in the nitrogen and phosphorus content in the effluent water.

NITROGEN FIXATION

Nitrogen fixation is restricted in natural waters to a few bacteria and a few forms of algae, particularly certain members of the blue-green algae. These organisms can convert nitrogen gas to ammonia and organic nitrogen. It is difficult at the present time to estimate the significance of nitrogen fixation. Certain forms of algae, such as Aphanizomeon and Anabaena are frequently associated wills highly eutrophic waters and are nitrogen fixers. On the other hand, Mycrosystis is also associated with highly eutrophic waters and it is not a nitrogen fixer. It is possible that nitrogen fixation occurs at such a rate as to not significantly affect the over-all nitrogen budget of a given body of water.

MISCELLANEOUS SOURCES

Among the miscellaneous sources of nutrients to lakes are ducks, geese and other organisms. On the one hand, wild duck populations probably do not add significant amounts of nutrients to the water. Since the ducks feed primarily in the water, they simply increase the rate of recycling of nutrients within the water. On the other hand, domestic duck populations such as those in zoos or in parks can contribute nutrients to the water in direct proportion to the amount of feeding by individuals that takes place. A similar problem exists with maintaining large herds of deer and other animals where these animals are fed near a lake shore. Wild geese feed primarily on land and, therefore, can increase the flux of nutrients from the land to the water.

Based on the foregoing discussion, aquatic plant nutrients are derived from many different sources. It is clear that for any given lake a detailed study of each of these potential sources must be made. A study of the nutrient sources for Lake Mendota (in Madison, Wisconsin) was made several years ago (Table 2). Examination of this table shows that the phosphorus is primarily derived from cultural sources, i.e., the waste waters or activities of man. Nitrogen for this particular lake, however, is derived from non-cultural sources such as rainfall, ground water, etc.

Table 2. Estimated Nutrient Sources of Lake Mendota*

Source

Annual contribution
(pounds)

Estimated contribution
(per cent)

Nitrogen

Phosphorus

Nitrogen

Phosphorus

Municipal and industrial waste water

47,000
(total)

17,000
(total)

10

36

Urban runoff

30,300
(soluble)

8,100
(soluble)

6

17

Rural runoff

52,000
(soluble)

20,000
(soluble)

11

42

If other lakes had similar sources it would be logical to proceed with an attempt to control phosphorus inputs, since it would be extremely difficult, if not impossible, to control nitrogen. It may, however, not be possible to keep the elements below critical levels in any type of control program because of the wide variety of sources and particularly since some of these sources, such as stormwater runoff, are not amiable to control at the present time.

MEASUREMENT OF EUTROPHICATION

At the present time, there is no one single analytical tool to measure the degree of eutrophication of a given body of water. Instead, most experts feel the best approach is to measure many different parameters and to synthesize the results into a general pattern which will give an over-all, somewhat average degree of eutrophication for the water. This situation is likely to change within a few years since it may be possible, through the use of systems models, to develop numerical scales for comparing the eutrophication of one lake with that of another. However, even this approach will require large numbers of different parameters to be measured in order to assess the current degree of eutrophication. Fruh et al. (1966) have reviewed this subject. Many of the parameters that should be measured are mentioned under the following topics.

STANDING CROP OF ALGAE AND AQUATIC PLANTS

Since the problems of eutrophication are caused by excessive numbers of planktonic and attached algae and higher aquatic plants, it is logical to use the total numbers of these organisms present as an estimate of the current degree of the eutrophication of the water. Unfortunately, this is extremely difficult to do since it requires a team of scientists to collect the samples and enumerate and identify the organisms present. In order to circumvent this difficulty in obtaining this kind of information, numerous other methods have been proposed for assessing the total biomass of planktonic algae.

AMOUNT OF SUSPENDED SOLIDS

For example, the suspended solids in the water are sometimes used as a measure of the algal populations. The problem with suspended solids is that the majority in most waters are nonliving. In some lakes, there are roughly 10 times more nonliving than living particles of organic matter present in tile sample.

VOLUME OF ALGAE

Others have proposed that the volume of algae be used, i.e., the amount that would be obtained in a graduated centrifuge tube. Under extreme conditions of eutrophication this can give some estimate of the total numbers. Again, though, the problem of living versus nonliving matter must be considered.

AMOUNT OF CHLOROPHYLL

One of the most frequently used methods is one employing the extraction of chlorophyll from the sample. Chlorophyll is present in all plants in sufficient amounts that it can be extracted with various solvents and estimated by means of a spectrophotometer. The problem with chlorophyll is that it works reasonably well for relatively pure cultures of one type of organism. However, with mixed populations of organisms, particularly where there is one type of organism one week and another the next week, it is found that the correlation between the chlorophyll content and the total numbers of mass of algae in the water is frequently is very poor.

NUMBER OF ALGAL BLOOMS

In advanced stages of eutrophication, one of the somewhat subjective types of measurements that could be used to assess the degree of eutrophication is the number of objectionable blooms of algae. Bloom is a term used by aquatic scientists to mean a large number of a certain type of organism. Although there is no general agreement on the exact number of organisms that constitute a bloom, frequently 0.5 to 1 million cells per liter is used. A bloom of planktonic algae usually lasts in the order of a week or so during the summer period in a moderately eutrophic lake. Many lakes have half a dozen or so of these blooms per summer where the numbers of algae fluctuate widely from week to week. If some estimate of the frequency and severity of obnoxious blooms were recorded, it would be an important measure of the degree of eutrophication.

PHOTOSYNTHESIS

Many investigators have proposed that a measure of the photosynthesis of the organisms present in the water be used as a criterion for determining the degree of eutrophication of a body of water. Here, the problem is primarily one of correlating the activity as measured by photosynthesis with water quality problems. Some groups of organisms present in lakes could be photosynthesizing at a high rate, yet not cause significant water quality problems.

PRODUCTIVITY INDEX

Probably one if the better approaches to this is the combination of standing crop and primary production measured by photosynthesis. The productivity index proposed by Strickland and Parsons (1960) in which the primary production is divided by the biomass, might give a better correlation between the degree of eutrophication and its effect on man.

HYPOLIMNETIC OXYGEN CONCENTRATIONS

One of the more frequently-used parameters for assessing the eutrophication of lakes is the oxygen concentration in the hypolimnion. Hypolimnetic oxygen depletion in lakes that are sufficiently deep to stratify is probably the most widely used index for separating oligotrophic from eutrophic lakes. However, there are many problems with this index. The rate of depletion of oxygen from the hypolimnion of a lake depends to a significant degree on the lake's morphology, e. g., its area-to-volume ratio. Lakes that have large hypolimnetic volumes compared with their surface area will lose their oxygen at a significantly lower rate than lakes that have large surface areas and small hypolimnetic volumes. One of the complicating factors is the fact that in many lakes the most significant source of oxygen demand is the accumulated reduced iron, manganese and sulfide species in the lake sediments. Often eutrophic lakes contain thousands of parts per million of iron and sulfur species on a dry weight basis. These materials will react rapidly with dissolved oxygen. The lakes which are not stratified generally have a thin layer of oxidized iron hydroxide on the surface of the sediments. However, once the lake becomes stratified and renewal of oxygen from the atmosphere can no longer take place, this layer of oxidized iron oxide will be reduced, and in turnit is generally found that the oxygen in the hypolimnion is fairly rapidly depleted by abiotic chemical reactions. This statement should not be interpreted to mean that the primary production in the surface waters of a lake does nut control the hypolimnetic oxygen depletion; it does, particularly in oligotrophic and moderately eutrophic lakes. However, at some point in the eutrophication of a lake, there will be significant accumulation of reduced iron and sulfur species which can exert the major oxygen demand during periods of thermal stratification. Under these conditions the epilimnetic production of aquatic plants may change significantly through the years, yet the rate of depletion of the hypolimnetic oxygen will not change since it is controlled to some extent by abiotic reactions.

LIGHT PENETRATION

Light penetration is probably the most widely used measure of eutrophication. Although sometimes criticized as being an extremely crude instrument, the Seechi disk, which consists of a plate about a foot or so in diameter painted in black and white quadrants attached to a metered rope or line, is an important tool in limnological investigations involving eutrophication. One of the most significant effects of eutrophication on water quality is a decreased clarity of water. This decreased clarity of water results from light scattering from the microscophic plants that are produced in the water. The depth at which a Secehi disk can be dropped and still be visible is an estimate of the amount of phytoplankton present in the water. Although this technique involves many problems, it is an important one in that it is inexpensive and can he readily performed by almost any individual. In almost every case where it has been used, it is clearly shown that, as a lake becomes more eutrophic, the depth at which a Secchi disk can be seen decreases significantly.

AQUATIC PLANT NUTRIENT CONTENT

Another parameter that can he used to assess the degree of eutrophication of waters is the aquatic plant nutrient content. Although it is difficult to establish meaningful, critical concentrations that are applicable to many different waters, the nitrogen and phosphorus concentrations determined by Sawyer are often cited as being the critical levels that separate oligotrophic from eutrophic waters. These critical concentrations are often based on the excessive growths of aquatic plants that produce aesthetically unpleasing water. As has been pointed out under an earlier topic, it is quite possible that concentrations considerably less than these amounts could cause significant deterioration in water quality. particularly with respect to the use of the water for domestic water supplies. The use of these critical concentrations to divide oligotrophic from eutrophic lakes must be viewed with caution.

PLANT REGRESSION

Another parameter that could be used to estimate the degree of eutrophication of a lake is the regression of higher plants in the water. Here. we are concerned with the question of what is the maximum depth to which a rooted aquatic plant can grow in a given lake. This maximum depth is determined to a significant degree by light penetration. In some lakes it has been found that as the lake becomes more eutrophic the maximum depth at which higher plants can grow decreases. For example, plants may grow at 20 to 30 feet of water during the more oligotrophic stages of a lake, while in the eutrophic stages they may be restricted to depths of 5 to 10 feet. This is because the phytoplankton develop in sufficient numbers each year to block off the light to such an extent that plants which would normally grow in deeper waters in more oligotrophic conditions simply cannot develop because they do not receive sufficient light.

SEDIMENT COMPOSITION

A possible means of assessing the current degree of eutrophication of a lake is to measure the composition of its sediments. Sediment provide a geological record not only of the events that have occurred within a lake, but also of the events that have occurred within a watershed. It is extremely difficult at the present time to determine the sources of materials in the sediment. There is ample evidence that the carbon present in lake sediments, particularly the organic carbon, is derived primarily from the watershed; yet, it is reasonable to expect that, as a lake becomes more eutrophic, the total amount of organic carbon deposited in the sediments increases. It is also expected that as a lake becomes more eutrophic greater amounts of the phosphorus, nitrogen and other aquatic plant nutrients would be deposited in the sediments. Yet, at the present time, work in this area has not clearly demonstrated a relationship between the chemical composition of the sediments and the degree of eutrophication.

A more fruitful approach is to examine the sediments for specific types of organisms, particularly those with parts which are well preserved in the sediments. Probably one of the best groups for this purpose is the diatoms. The diatoms are a group of algae which have siliceous shells, many of which are well preserved in the sediments. By determining the number and types of such shells in sediments, it is possible to gain some inference about the rate of eutrophication of a given body of water.

In summary, there is no single parameter that can be used to estimate the current degree or rate of eutrophication of a lake or to compare the degree of eutrophication between lakes. Many different parameters must be used and each one must be weighed according to the general characteristics of the lake.

EFFECTS OF EUTROPHICATION

The eutrophication of a water may have a significant effect on domestic, industrial, recreational and agricultural uses of the water. Typical effects in each of these areas are discussed here.

DOMESTIC AND INDUSTRIAL USES

The presence of excessive amounts of nitrogen and phosphorus compounds can have a direct effect on water quality when ammonia exerts an increased chlorine demand and when the various phosphate species, particularly the condensed phosphates, affect the coagulation of particulates in the water with iron and aluminum salts. It is also possible that the nitrate content of the water could be increased significantly to cause problems of methemoglobinemia. However, usually it is found that the direct effects of nitrogen and phosphorus species on water quality are minimal compared with the indirect effects of these nutrients which result in the growth of excessive amounts of aquatic plants.

The excessive growth of these plants can significantly decrease water quality. For example, algae can cause such an increase in turbidity or reduction of light penetration in water that they have to be removed in water treatment. Generally their removal involves the addition of coagulants such as iron or aluminum salts followed by filtration through sand or other media filters. Whenever large concentrations of algae are present in the water, the rate at which these filters become clogged increases to such an extent that the filters have to be cleaned more frequently than they would if no algae were present.

The presence of algae and other plant remains in a water supply will increase the chlorine demand of the water since chlorine species will react with the remains of these organisms to form organochlorine compounds and oxidation products. It is believed by some that the presence of algae and other organisms in a water supply could protect pathogenic organisms from being destroyed by chlorine. For example, various kinds of higher animals could protect some pathogenic bacteria in their intestinal tract from destruction by chlorine normally added for disinfection purposes.

Probably the most significant effect of eutrophication of water supplies is the increased frequency of taste and odor problems. Many algae are notorious for causing tastes and odors in water supplies at very low concentrations of the organisms. A few cells per liter of some algae are said to impart a distinct odor to the water. Algal odors arise either from direct excretion of various organic compounds from the algae while they are alive or shortly after their death, or by the growth of various kinds of fungi on alga remains. The actinomycetes are such fungi; under certain circumstances, they seem to grow in large numbers shortly after the death of blooms of algae.

Some water-plant operators can tell the type of algae present in the water supply by their characteristic odors which may resemble the odors of cucumbers, pigpens, etc. The removal of these tastes and odors from water supplies often involves the addition of activated carbon and/or various kinds of oxidizing agents such as chlorine, ozone or permanganate in an attempt to either sorb or oxidize the odor.

In addition to causing odors and tastes, the growth of algae and aquatic plants can also increase the color content of the water. In general, dead algae release organic compounds which cause a pale yellow color in the water. The removal of color from the water often involves the addition of various oxidizing agents and coagulants with or without activated carbon for sorption of the organics.

Another effect of eutrophication on a water supply concerns eutrophic lakes where oxygen is depleted in the hypolimnion during summer stratification. The lack of oxygen in these deeper waters often causes large concentrations of iron, manganese and/or sulfide species to occur which in turn cause serious water quality problems. If this lake water is used for domestic or industrial purposes, the water-plant operator must take the warm epilimnetic waters which contain large concentrations of algae, instead of taking the cold hypolimnetic waters which are lower in algal numbers.

The location of the depth of a water-supply intake in a lake is dependent upon the degree of eutrophication of the lake. Generally, in oligotrophic lakes the over-all water quality is better in the hypolimnetic (bottom) waters than in the epilimnetic (surface) waters. The bottom waters are colder and contain less algae and particulate matter. However, in eutrophic lakes, the loss of oxygen from the bottom waters results in anaerobic conditions which lead to the formation of reduced species of iron, manganese and sulfur. The oxidized forma of iron (FeIII) and manganese (Mn IV) in natural water are the predominant forms in the presence of dissolved oxygen. Since these forms are insoluable as Fe(OH) ₃ and MnO ₂ in natural waters, they settle to the bottom of the lake and become incorporated in the sediments. Under oxidizing conditions, sulfur is present as sulfate and does not cause any water quality problems in most water supplies. In eutrophic lakes which experience the loss of all dissolved oxygen in the hypolimnion during periods of thermal stratification, anaerobic conditions develop that promote biochemical-chemical production of ferrous iron, manganous manganese and hydrogen sulfide. Since these reduced forms of iron and manganese are highly soluble, the concentrations may increase to levels which cause serious water quality problems.

From a water quality point of view for water supplies, the surface waters of all lakes tend to be of much poorer quality. However, in eutrophic lakes the presence of large amounts of iron, manganese or hydrogen sulfide causes serious water quality problems with the result that the water-supply intake must be adjusted to take the surface waters of the lake in order to avoid the high iron, manganese and hydrogen sulfide found in the bottom waters.

There are reports that organics such as those present in natural color cause an increased fouling of ion exchange resins. Although work in this area to date has not clearly demonstrated the relationship between frequency of fouling and eutrophication, it is reasonable to suppose that further studies may show that more eutrophic waters tend to foul ion exchange resins at a greater rate.

In summary, the eutrophication of domestic and industrial water supplies causes significant problems in water quality. In some cases, the seriousness of these problems can be measured by the increased treatment costs necessary to restore desirable water quality. For example, many water treatment plants keep accurate records of all chemical doses used. Eutrophication could conceivably be measured then by the amounts of chemicals that have been used at a given water plant in order to treat the water.

RECREATIONAL USES

Probably the most significant effect of eutrophication on recreational uses of water is with respect to its aesthetic quality. In general, excessive growths of aquatic plants cause a significant decrease in the aesthetic quality of the water. Certainly some plants, such as water lilies, are pleasing to the eye. However, when they become so thick in an area that it becomes impossible to swim, boat or fish, then their pleasing qualities rapidly become aesthetically undesirable.

These areas where the effects of growths of excessive amounts of aquatic plants are the most pronounced are usually the same areas where man's contact with the water is greatest. The nearshore environment-the shallow waters near the edge of a lake or stream-can become completely choked with various kinds of rooted aquatics and attached algae. The thickness of growth of these plants can make it almost impossible to use the water in this area for any purpose.

Under certain conditions, even the planktonic algal growth that develops in the middle of the lake can accumulate as thick mats of decaying algae along the shoreline. In severe cases, these mats can be so thick that turtles, ducks and other aquatic animals walk on top of them! Their high protein content results in hydrogen sulfide production which in turn develops into an extremely foul-smelling condition that is sometimes mistaken for the discharge of untreated municipal waste. The situation can become so severe on some lakes that shoreline property decreases in value, while the property away from the shore is increasing in value.

In addition to causing aesthetic deterioration of water used for recreational purposes, eutrophication can also cause a deterioration of a lake's fishery which, in terms of total production, depends on the total input of aquatic plant nutrients. Through the food web, the plant nutrients combine through photosynthesis to produce the aquatic plants which feed the aquatic animals which eventually become fish food. Most eutrophic lakes have the greatest production of fish. Eutrophication, in addition to increasing the total fish production in the lake, also changes the type of fisheries. This change is generally one of complete loss of the cold-water fishes such as trout and cisco and almost complete dominance of the less desirable warm water fish such as carp and bullheads. The loss of cold-water fisheries is the result of the depletion of oxygen below the thermocline during the summer stratification period. In an oligotrophic water, oxygen is lost during summer stratification below the thermocline so that a fish that would normally inhabit cold waters simply does not survive there. In summary, the effect of eutrophication on fisheries is one of increased total fish production which results in less desirable fish.

AGRICULTURAL USES

The eutrophication of a water can have significant effect on agricultural uses of the water. Some of the blue-green algae are reported to excrete highly toxic substances which can cause death of waterfowl, cattle, sheep and other animals. Although it is not known how frequently this occurs, some studies have shown that toxins produced by these algae could be significant in certain situations. With respect to human health, however it is estimated that the average human being would have to consume about 1 to 2 quarts of the "pea soup" that results from an excessive bloom of blue-green algae before he would be adversely affected.

Agricultural uses of eutrophic water are also affected where such water is transmitted in canals. The transmission of, water in irrigation canals can he greatly inhibited by excessive growths of aquatic weeds. The weeds increase the frictional resistance and, in addition, these same weeds can cause significant losses of water through increased evapotranspiration. This problem is particularly important in the arid areas of the western part of the United States where long irrigation water canals are used.

METHODS OF REDUCING THE EFFECTS AND RATE OF EUTROPHICATION

The eutrophication of a lake can be controlled or its effects on water minimized by reducing the nutrient input to the lake; increasing nutrient output from the lake, immobilizing nutrients within the lake and controlling excessive growths of algae and macrophytes within the lake. Various methods that have been proposed in each of these areas are summarized under the following topics.

NUTRIENT REMOVAL FROM WASTE WATERS

Since domestic waste waters represent a potentially significant source of aquatic plant nutrients, it is often the source that is looked to first for control. The nitrogen and phosphorus and, to some extent, the other trace elements can be removed from waste waters so that these waters will not be as fertile as they would have been if no nutrients were removed. Various laboratory pilot plant and field scale experiments have shown that both nitrogen and phosphorus can be removed from waste waters at a moderate cost. Phosphorus removal is accomplished by alum flocculation, ferric iron flocculation or lime precipitation, all three of which will remove 80 to 90 per cent of the phosphorus present in waste waters. Removal of ammonia and other nitrogen species can be done by such means as ion exchange, stripping ammonia at high pH in a gas stripping tower or bacterial denitrification in which ammonia is oxidized to nitrate which then becomes dentrified to form nitrogen gas. These various methods have been applied and can bring about nutrient reduction.

In general, however, these methods will cause a cost increase over conventional waste-treatment costs. At the present time, the cost of phosphorus removal is in the order of a few cents per thousand gallons depending on the size of the plant, with larger plants able to accomplish phosphate removal more inexpensively per unit size. This represents roughly a doubling of conventional waste-water-treatment costs. Nitrogen removal is now more expensive although it is expected that the cost will decrease if additional experience in treating water for nitrogen removal is obtained. It is likely that significantly large amounts of funds will soon be spent, first for phosphorus removal and then, in a few years, for nitrogen removal from waste waters.

DIVERSION OF WASTE WATERS

The most frequently used method to reduce lake eutrophication primarily caused by waste waters is to divert the waste waters around or away from the lake. This approach has been used in Madison, Wisconsin, and is being tried in Lake Washington in Seattle, Washington, and to some degree, in Lake Tahoe. While this method does eliminate the problem from the original lake that received the waste waters, it also increases the problem for receiving waters. From a long-range point of view, wastewater diversion is not a satisfactory solution to the problems of eutrophication. Wastewater treatment will have to be practiced as a means of controlling nutrients.

DREDGING

A procedure that can be used to remove nutrients from a lake involves dredging of lake sediments. As previously pointed out, a lake's annual process of self-fertilization and subsequent release of nutrients from sediments to overlying waters may, for some lakes, be one of the primary sources of the lake's nutrients. If nutrient-rich sediments could be dredged from the lake, it is possible that this self-fertilization would be decreased.

One of the problems with dredging, however, is that the nutrient content of lake sediments does not usually change drastically with depth. Recently conducted studies show that, for many lakes, phosphorus and nitrogen content of sediments is approximately the same at the surface as 10 to 15 feet below the surface, although there are some indications that the leachability of elements deep in the sediments may be somewhat less than the leachability of surface sediments. Therefore, it is reasonable to question whether or not dredging will have a significant effect on nutrient release. Certainly any undertaking in which dredging is proposed should be preceded by studies of nutrient release from the various types of sediments that will be dredged.

Another problem that usually accompanies the dredging of sediments is a shift from the growth of rooted aquatic plants to planktonic algae. This shift is due to the fact that rooted plants cannot develop in moderately deep water since algae in the overlying waters shut off the light available to them. As a result of dredging, a lake may be changed from one with an aquatic weed problem to one with an algal scum problem due to the growth of excessive numbers of planktonic algae.

Dredging of lakes clearly needs to be more properly evaluated before it can be used as an effective tool in eutrophication management. Care must be exercised in methods of disposal of the dredged material so that the nutrients present in these materials are not leached out and carried to a nearby watercourse. Considerable concern has been expressed about the effect of the disposal of material dredged from the Great Lakes and its harbors. The hopper dredges used to remove sediments from harbors do not remove large amounts of nutrients since the dredged materials are washed as part of the dredging operation to remove fine particles. Various studies have shown that these fine sediments contain the largest fraction of plant nutrients.

FLUSHING

Flushing can be effectively used to control nutrients within a lake. If large volumes of water low in nutrient content are available, flushing the lake with this water will increase water quality and decrease the frequency and seventy of algal blooms. However, lakes rarely have large quantities of nutrient-poor water available for flushing purposes.

ZONING

It is possible that one of the best methods to control nutrient flux for a given lake is to control land use within the watershed . For example marshes could be zoned to prevent their being dried up for agricultural or urban purposes. Zoning regulations could also control the type of farming and the types and amounts of fertilizers used in order to protect a given watershed.

CHEMICAL CONTROL OF NUISANCE PLANT GROWTHS

Both algicides and herbicides are being used to control the excessive growths of aquatic plants in natural waters. Algicides such as copper sulfate can effectively control algae. Herbicides such as 2, 4-D and sodium arsenite do control rooted aquatic plants. In general, the application of these chemicals to a water requires close attention and supervision, requires large expenditures of funds and must be done at frequent intervals during the growing season. On some occasions, it has been found that whenever a lake is treated to remove certain kinds of algae, a few weeks later another type of algae will rapidly develop and replace that which has been killed off. A potentially quite important aspect of the use of algicides and herbicides is the question of their effects on other organisms present in the water or on other uses of the water. If these chemicals persist in the water, there are always questions concerning their toxicity to fish, to fish-food organisms, or to man if the water is used for domestic or industrial purposes.

This toxicity question may be broken down into two parts. On the one hand, there is an acute toxicity that is associated with the application of the materials. If any of these chemicals are applied in excessive doses, they can cause fish kills. On the other hand, the more important question today, since acute toxicity can be readily taken care of by proper application, is one of chronic toxicity. Will the presence of these chemicals cause genetic changes? Are they carcinogenic; do they affect the rate of reproduction? These kinds of questions regarding long-lasting effects on the aquatic populations cannot be answered at the present time because of insufficient knowledge.

BIOLOGICAL CONTROL OF NUISANCE PLANT GROWTHS

The use of biological controls of excessive growths of algae and macrophytes has not been developed to the point where any potentially effective agents are likely to be found in the near future. The most promising results to date in this area have come from the work on the isolation of a virus that shows promise of being specific for blue-green algae. If such a virus can be found and readily cultured, it may be possible to use it to control excessive blooms of blue-green algae.

HARVESTING

Other methods of reducing the nutrient content or the flux to a given body of water include the removal of weeds, debris and rough fish and the harvesting of algae and aquatic weeds along the shore. Although harvesting does remove certain amounts of nitrogen and phosphorus, in general, it does not make significant inroads on the nutrient balance of a lake. Harvesting procedures are, however, justified in terms of improving the aesthetic quality of the lake by making it useful for swimming, boating and fishing. In situations where total nutrient input is low, harvesting may remove a significantly large proportion of nutrients from the lake and, therefore, would be justified as a nutrient removal procedure.

Many express the opinion that excessive growths of aquatic plants could lead to a harvestable crop of fish or other organisms. As previously explained, larger crops of fish are produced in eutrophic lakes; however, the large fish crops do not occur until sufficiently large populations of algae cause serious deterioration of water quality. In Florida, the manatee is used to keep some of the canals from becoming completely choked with macrophytes. While these animals clear the canals by consuming large quantities of aquatic plants, they are not able to remove significant amounts of nutrients from the water.

Although the harvested weeds do have a good fertilizer and humus potential and could be used as all agricultural fertilizer, the problems of handling and hauling them greatly restrict their use fur this purpose. Frequently the harvested aquatic weeds and rough fish must be hurled in landfills because no one wants the material.

MIXING OF LAKES

One of the methods that is sometimes proposed to control eutrophication is to destratify lakes with the use of compressed air or pumps. The basis of this method is that it is generally believed that aquatic plant nutrients such as phosphorus are not released under aerobic conditions. Recent studies at the University of Wisconsin Water Chemistry Laboratory have shown that this is not the case. Significant phosphorus release occurs in many types of lake sediments under aerobic conditions, and, therefore, the aeration of a body of water for the control of algae is of questionable value particularly if the aeration destroys the thermocline. The thermocline is an effective barrier to nutrient transport from the sediments in many lakes. Very small amounts of chemicals are transported across it. The thermocline is present throughout the growing season which is the critical period of the year for transport of nutrients from the sediments to the overlying water. Therefore, rather than mixing a lake to bring about complete oxygenation and to destroy the thermocline, it would be better to aerate the hypolimnion of a lake without destratification.

Special devices are available which enable this to be done. Hypolimnetic aeration with either air or gaseous oxygen allows the cold water fisheries to exist and would tend to control the nutrients to some degree at the same time. This method of aeration would reduce the amounts of nutrients circulated in overlying waters at fall overturn and would quite possibly take less energy than to completely mix a body of water.

CONTROL OF AGRICULTURAL SOURCES OF NUTRIENTS

Agricultural sources of nutrients can be controlled through educating the farmer in terms of when to apply nutrients, what concentrations to apply and how to control soil erosion and other conditions that tend to promote high nutrient fluxes from farmland. The manure problem that exists in Wisconsin and other nearby states can be controlled by having the farmer store the manure in tanks over the winter period and then spread it on the land after the ground has thawed in the spring.

URBAN DRAINAGE

Control of urban nutrient sources at the present time has little promise. The volume of storm waters that occur during normal thundershower activity is often such that it is impractical to consider diverting these waters or even treating them by any of the conventional means readily available today. The future in control here may lie in understanding the sources of nutrients and thereby controlling them at their source. One possible method is to decrease nutrient input to lakes by increasing street sweeping and effective leaf pick-up.

HYPOLIMNETIC WITHDRAWAL

Eutrophic lakes that are sufficiently deep to develop a stable thermocline accumulate higher concentrations of nitrogen and phosphorus in hypolimnetic waters than they do in the epilimnetic waters. The higher concentrations are derived from the sediments under anaerobic conditions. In some lakes, hypolimnetic withdrawal of water will result in a higher nutrient flux from the lake than would be obtained with epilimnetic removal of water.

In some cases where hypolimnetic withdrawal of water from eutrophic lakes has been practiced, serious hydrogen sulfide odor problems have developed near the point of water discharge due to the release of this gas from the anoxic waters of the hypolimnion of the lake.

WATER-LEVEL MANAGEMENT

Water-level manipulation in impoundments and, where possible, in lakes can reduce the crops of rooted aquatic plants. In cold climates a combination of lowering water levels and freezing will reduce macrophytes in lakes. However, lowering of water levels to achieve freezing or dessication may result in an increased release of nitrogen and phosphorus species.

IMMOBILIZATION OF NUTRIENTS

Aluminum and iron salts may be added directly to the lake to remove phosphorus from the lake water and carry it to the sediments. This method of nutrient control needs study to define the required chemical dosages and the necessary frequency of treatment.

RATE OF RECOVERY OF A LAKE UPON APPLICATION OF REMEDIAL ACTION TO CONTROL EXCESS NUTRIENT DISCHARGE TO A LAKE

The rate of recovery of an excessively fertilized lake after a reduction in nutrient input is dependent on many factors, the more important of which are the morphology of the lake including its drainage basin, the hydrology of the lake (relative amounts of surface and ground water), the theoretical flushing period of the lake, the amount of short-circuiting of its inlet and outlet waters, the amounts, forms and distributions of aquatic plant nutrients in the sediments of the lake, the magnitude of nutrient input reduction, the chemical composition of the water, the chemical processes occurring in the lake, etc. The interrelationship of the various factors is poorly understood. There is a tendency to use the hydraulic flushing characteristics of the lake as a basis for predicting the rate of recovery upon nutrient input reduction. For chemical species such as phosphorus, it is known that this approach grossly overestimates tile rate of recovery. The proper approach for estimating the rate recovery after phosphorus input reduction is to use a phosphorus residence lime model rather than the hydraulic residence time model Where such models have been applied, it is generally found that the phosphorus residence time model predicts a rate of recovery on the order of a year or two, while the hydraulic residence time model predicts a many-year rate.

CONCLUSIONS

Eutrophication of natural waters is one of the most significant water quality problems that man faces today. The growth of excessive amounts of aquatic plants can cause a significant decrease in water quality resulting in increased costs for water treatment, decreased quality for use in recreational purposes and a hindrance to the use of water for agricultural purposes. The nutrients that cause this excessive plant growth are nitrogen, phosphorus and other trace elements. These elements are derived from many sources, the most important of which are domestic waste waters, urban drainage, agricultural sources, the atmosphere, ground water and, to some degree, lake sediments.

The control of eutrophication can best be effected on point sources such as waste water effluent by nutrient removal. Other methods of control which show promise include removal of weeds, debris and rough fish, dredging of lake sediments, flushing and zoning. Chemicals such as herbicides and algicides can be used to provide temporary relief from excessive growths of aquatic plants. However, their use may result in significant water quality problems at some future date.

There is an urgent need for additional research in all aspects of eutrophication ranging from the hydrodynamics, hydrogeology, hydrobiology and water chemistry of lakes and streams to the various engineering aspects of nutrient control including the social, political and economic aspects of water resources management. The control of eutrophication of natural waters will require cooperative efforts of aquatic scientists, engineers, economists, social, political and legal experts. Only through the combined efforts of these individuals will it be possible to manage water resources for the betterment of mankind.

LITERATURE CITED

Anonymous. 1961. Algae and metropolitan wastes. Trans. Seminar on Algae and Metropolitan Wastes, Cincinnati, Ohio. R.A. Taft San. Engr. Center.

Anonymous. 1967. Environmental requirements of blue-green algae. Proc. Symposium, Univ. Washington and Fed. Water Pollution Control Admin. Pacific Northwest Water Lab.

Anonymous. 1967. Excessive water fertilization. Report to Water Subcomm. of Nat. Res. Comm. of State Agencies, Madison, Wis.

Anonymous. 1969. Effects of fertilizers on water quality. Nat. Fertilizer Develop. Center, Tenn. Valley Author.

Beeton, A.M. 1965. Eutrophication of the St. Lawrence Great Lakes. Limnol. Oceanog. 10:240-254.

Edmondson, W.T. 1968. Water-quality management and lake eutrophication: the Lake Washington case. In: Water Resources Management and Policy. Univ. Washington Press.

Foge, G.E. 1965. Algal Cultures and Phytoplankton Ecology. Univ. Wisconsin Press.

Frey, D.E. (ed.) 1963. Limnology in North America. Univ. Wiscorsin Press.

Fruh, E.G., K.M. Stewart, G.F. Lee and G.A. Rohlich. 1966. Measurements of eutrophication and trends. Jour. Water Poll. Control Fed. 38:1237-1258.

Goldman, C.R. (ed.) 1966. Primary Production in Aquatic Environments. Univ. California Press.

Hasler, A.D. 1947. Eutrophication of lakes by domestic drainage. Ecology 28:383-395.

Hutchinson, G.E. 1957. A Treatise on Limnology. Vol. I, Geography, Physics, and Chemistry. John Wiley and Sons, New York.

______________ 1967. A Treatise on Limnology. Vol.11, Introduction to Lake Biology and the Limnoplanklon. John Wiley and Sons, New York.

Jackson, D.F. (ed.) 1964. Algae and Man. Plenum Press.

_______________ 1968. Man and the Environment. Syracuse Univ. Press.

Lee, G.F. (chairman) 1966. Report on the nutrient sources of Lake Mendota. Lake Mendota Problems Comm., Madison, Wis. (revised 1969).

_______________ 1970. Factors affecting the exchange of materials between waters and sediments. Literature Review No. I, Eutroph. Inform. Program, Univ. Wisconsin.

Lee, G.F., and E.G. Fruh. 1966. The aging of lakes. Ind. Water Engr. 3:26-30.

Lewin, RA. 1962. Physiology and Biochemistry of Algae. Academic Press.

Machenthun, K.M. 1962. A review of algae, lake weeds and nutrients. Jour. Water Poll. Control Fed. 34:1077-loss.

1965. Nitrogen and phosphorus in water. An annotated selected bibliography of their biological effects. U.S. Dept. Health, Education and Welfare.

Machenthun, K.M., and W.M. Ingram. 1966. Algal growth factors other than nitrogen and phosphorus. Fed. Water Poll. Control Admin.

_______________ 1967. Biological associated problems in freshwater environments: their identification, investigation and control. Fed. Water Poll. Ccntrol Admin.

Machenthun, K.M., W.M. Ingram and R. Porges. 1964. Limnological aspects of recreational lakes. U.S. Dept. Ilcalth, Education and Welfare.

Middlebrooks, E.J., T.E. Maloney, C.F. Powers and L.M. Kaack. 1969. Proceedings of the eutrophication.biostimulation assessment work. Fed. Water Poll. Control Admin., Corvallis, Ore.

National Academy of Science. 1969. Eutrophication: Causes, Consequences and Correctives. Nat. Acad. Sci., Wash., D.C.

National Technical Advisory Committee (to the Secretary of the Interior). 1968. Water quality criteria. Fed. Water Poll. Control Admin.

Sawyer, C.N. 1966. Basic concepts of eutrophication. Jour. Water Poll. Control Fed. 38:737-744.

Sawyer, C.N., J.B. Lackery and A.T. Lenz. 1945. Investigation of the odor nuisances in the Madison Lakes, particularly Lakes Monona, Waubesa and Kegonsa, from July 1943 to July 1944. Report to Governor's Committee, Madison, Wis.

Stewart, K.M., and G.A. Roblich. 1967. Eutrophication - a review. Calif. State Water Quality Control Bd., Pub. 34.

Strickland, J.D.H. 1960. Measuring the production of marine phytoplankton. Fish. Res. Bd. Canada, Bull. 122.

Veatch, J.O., and C.R. Humphrys. 1964. Lake terminology. Dept. Res. Develop., Agric. Exp. Sta., Mich. State Univ.

Vollenweider, R.A. 1968. Scientific fundamentals of the eutrophication of lakes and flowing waters, with particular reference to nitrogen and phosphorus as factors in eutrophication. Organ. Econ. Coop. and Develop., Directorate for Scientific Affairs.

_____________ 1969. A manual on methods for measuring primary production in aquatic environments. International Biological Programme, Handbook 1 2.

Weibel, S.R., R.J. Anderson and R.L. Woodward. 1964. Urban land runoff as a factor in stream pollution. Jour. Water Poll. Control Fed. 36:914-924.

NOTE

Originally prepared for the Supplement to the Encyclopedia of Chemical Technology, John Wiley and Sons (1970), and printed here with their permission. Also published in essentially this form as Occasional Paper No. 2 of the University of Wisconsin Eutrophication Information Program.

References as:"Lee, G.F., 'Eutrophication,' Transactions of the Northeast Fish and Wildlife Conference, pp 39-60 (1973). "

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Reprinted from Transactions Northeast Fish and Wildlife Conference May 1972 p. 39-60 EUTROPHICATION G. Fred Lee Institute for Environmental Sciences The University of Texas at Dallas P.O. Box 688 Richardson, Texas 75080 ABSTRACT The eutrophication-excessive fertilization of natural waters is becoming one of the most important causes of water quality deterioration.

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Effect of Nitrate and Phosphate Levels on the Growth of Algae by the American Society for Microbiology

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Effect of Nitrate and Phosphate Levels on the Growth of Algae by the American Society for Microbiology

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Nitrate and phosphate are useful as fertilizers in gardening and agriculture, producing more abundant crops. However, since the mass production of ammonia during the 1940's by way of the Haber process, we have known that a phenomenon called "nitrate pollution" may occur. The experiment in this lesson plan demonstrates two main ideas. The first is a test of what levels of nitrate and phosphate allow for optimum algal growth. The second demonstrates at which levels of nitrate and phosphate algal blooms may occur, causing harm to an aquatic ecosystem.

Learning Objectives

After completing this lesson, students will be able to do the following:

1. Predict how increasing concentrations of nitrate and phosphate affect the growth of algae.

2. Explain how algal growth affects marine habitats.

3. Explain why observations from multiple iterations of the same experiment are necessary to draw conclusions.

Student Background

It is recommended that students have prior knowledge of algae's ability to carry out photosynthesis. Also, students should be familiar with laboratory safety.

Science Standards

This lesson addresses National Science Education Standards (1996):

Science as Inquiry - Use Appropriate Tools and Techniques to Gather, Analyze, and Interpret Data.

Science as Inquiry - Understandings About Scientific Inquiry.

Life Science - Populations and Ecosystems.

Life Science - The Interdependence of Organisms.

Science in Personal and Social Perspectives - Risks and Benefits; Environmental Quality.

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Effect of Nitrate and Phosphate Levels on the Growth of Algae

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The experiment in this lesson plan demonstrates two main ideas. The first is a test of what levels of nitrate and phosphate allow for optimum algal growth. The second demonstrates at which levels of nitrate and phosphate algal blooms may occur, causing harm to an aquatic ecosystem.

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Forty-five years ago, Lake Erie was so polluted that TIME magazine warned it was "in danger of dying by suffocation." A massive clean-up effort, involving everyone from local businesses to state and national policymakers, brought the lake back from the brink. Recently, algal blooms have once again tainted western Lake Erie with unhealthy, sometimes toxic, green slime. Why is this happening?

For the past forty years, scientists at Heidelberg University's National Center for Water Quality Research have been measuring pollution in the rivers and streams that feed Lake Erie. Decades of monitoring have led to an inescapable conclusion: phosphorus runoff, primarily from agricultural lands, is feeding explosive cyanobacterial growth in the warm, shallow waters of the western basin.

Understanding the source of the phosphorus pollution that threatens the health of Lake Erie, and of the communities that depend on it, is the first step toward finding solutions.

The History Of Lake Erie's Troubles

How Do We Know Phosphorus Is The Culprit?

In this video, research scientist Laura Johnson of the National Center for Water Quality Research at Heidelberg University explains how 40 years of data points to dissolved reactive phosphorus as the primary culprit behind Lake Erie's harmful algal outbreaks.

What is Toxic Algae?

Not all algae are harmful. Algae are natural components of marine and fresh water ecosystems, and form the foundation of most aquatic food chains. The most commonly occurring groups of freshwater algae are diatoms, green algae, and blue-green algae, which are more correctly known as cyanobacteria. Some cyanobacteria can produce potent toxins known as cyanotoxins.

Outbreaks of cyanobacteria that release toxins are commonly called "toxic algae" blooms. In recent years, toxic algae blooms involving a cyanotoxin called microcystin have led to several temporary "do-not-drink" warnings around the western Lake Erie basin.

A Tale of Two Rivers

The differences in how heavy spring rainfalls affect phosphorus loads in two watersheds - the Maumee and the Cuyahoga - show the different impacts of non-point sources (like the primarily agricultural lands in the Maumee River basin) and point sources (like the urban and industrial lands in the Cuyahoga River basin, which houses nearly 15% of Ohio's population). Both watersheds occasionally have combined sewer overflows (CSOs), but research suggests these volumes pale in comparison to the river volume during storms.

The charts below illustrate the spring 2015 phosphorus concentrations in the two basins. Note that in the Cuyahoga River basin, phosphorus concentrations (shown as brown dots) remained mostly level despite large spikes in water flow (shown as blue spikes) after heavy rains. In the Maumee River basin, by contrast, heavy rains led to dramatic spikes in phosphorus concentrations.

The phosphorus "concentration" is defined as the total amount of phosphorus in a defined volume of water - in this case, milligrams of phosphorus per liter of water. Learn more below about the different kinds of phosphorus, and which are most responsible for Lake Erie's algae outbreaks.

Point Source vs. Non-Point Source Pollution

There are two categories of pollution that contribute to Lake Erie's phosphorus loads: pollution from point sources like pipes from factories or water treatment plants, and non-point sources like runoff from fields. In general, point sources are associated with water use for domestic, commercial and industrial purposes, while nonpoint sources are associated with the interaction of land use activities and the hydrological cycle.

"Point source" pollution is defined by the U.S. Environmental Protection Agency (EPA) as "any single identifiable source of pollution from which pollutants are discharged, such as a pipe, ditch, ship or factory smokestack." In the case of water pollution, factories and sewage treatment plants are the most common point sources of pollution.

"Non-point source" pollution is defined as any source of water pollution that does NOT meet the legal definition of a "point source." Common sources of non-point source pollution include water running off from surface lands like cropland, urban runoff from streets and lawns*, faulty septic systems, and sediment from construction sites.

*NOTE: Some municipalities send some of this surface runoff into combined sewer systems that lead to sewage treatment plants. However, these systems are very expensive and not infallible.

The Role of Tile Drains

A large portion of the western Lake Erie watershed was originally the Great Black Swamp. Thus, farming and settlement was only possible after the widespread construction of drainage ditches and installation of "tile drains" beginning in the early 1900s. Tile drains are simply drain pipes buried beneath fields to help lower the water table and collect surface water after it has filtered through a few feet of soil and then whisk it away from the fields to avoid standing water and surface runoff.

Unfortunately, in the western Lake Erie region, heavy clay soils often develop cracks and pores that act like the drain in your bathtub: surface water quickly drains through the soil into the tile drain, carrying high concentrations of phosphorus with it. Although surface runoff can lead directly into ditches during large storm events carrying even higher concentrations of phosphorus, a majority of field runoff exits through tile drains. Both surface runoff and tile drains empty into ditches that lead to streams, which lead into rivers, which ultimately empty into Lake Erie, delivering damaging loads of phosphorus.

Why is dissolved phosphorus such a problem for Lake Erie?

There are two types of phosphorus that enter Lake Erie from the surrounding watersheds. Dissolved phosphorus is the phosphorus that remains in water after that water has been filtered to remove sediment and other particulate matter. Phosphorus that is attached to sediment or particulate matter is called particulate phosphorus. Together these two forms of phosphorus make up the total phosphorus concentration in a water sample.

Dissolved phosphorus is a special problem in Lake Erie because it is much more "bioavailable" to algae than particulate phosphorus. In other words, algae can easily consume dissolved phosphorus, leading to rapid algal growth. This type of phosphorus is sometimes called "dissolved reactive phosphorus." Dissolved phosphorus also tends to remain in the water, while particulate phosphorus settles to the lake bottom where it may no longer be available to algae. The amounts or loads of dissolved phosphorus entering Lake Erie have more than doubled since the mid-1990s.

Total Phosphorus includes all forms of phosphorus found in the water sample. Particulate Phosphorus will generally settle out of the water column and not be bioavailable to cyanobacteria and other organisms.

Dissolved Reactive Phosphorus is bioavailable to organisms and feeds harmful algal blooms. Dissolved reactive phosphorus comes from agricultural fertilizer and nutrient polluted runoff.

Dissolved phosphorus from agricultural runoff is the primary driver of Lake Erie's harmful algae outbreaks, and a recent report from the USDA-NRCS shows that 84% of phosphorus applied to agricultural land in the Lake Erie Basin is from commercial fertilizers, and 16% is from manure. While we can be quite certain about the sources of the majority of the phosphorus pollution, the solutions are harder to pinpoint. In part this is because agriculture is exporting a small amount of the phosphorus that is applied and many farms are at recommended soil test phosphorus levels. Also, agricultural lands in the Lake Erie watershed vary in the size of the operation, composition of their soil, even the amount of rainfall they receive. What works for one farm or livestock operation might not work for another, and changing the way farmers do business could have large economic costs. Making the wrong kinds of changes might not make things better for Lake Erie - it could even make things worse.

Here are some of the many opportunities for reducing phosphorus pollution while preserving farmland productivity.

Focus on Adaptive Management
Just as there's no "one size fits all" solution, the options for reducing nutrient pollution can change over time. Active monitoring and interpretation of the current conditions on farmlands is crucial to managing nutrient applications and keeping nutrient pollution out of waterways.

Follow the "4Rs" for nutrient stewardship
The 4Rs promote best management practices designed to ensure that the Right fertilizers and manures are applied at the Right rate, at the Right time, and in the Right place. These practices can include avoiding fertilizer and manure application to frozen fields; injecting fertilizer beneath the surface of the soil; and testing soils to know how much fertilizer will be needed for healthy crops. Learn More

Slow down the water

Reducing the rapid loss of water and concurrently stripping excess phosphorus out of water before it reaches waterways can help reduce pollution levels. Opportunities may include controlled drainage structures with bioreactors, blind inlets instead of tile risers, and saturated buffer strips. Cover crops and gypsum application, which would improve water infiltration and soil water storage may also help reduce the rapid delivery of water to drainage ditches and ultimately Lake Erie.

Opportunities may include restoring natural wetlands, installing artificial wetlands, or filtering water that exits tile drains. Cover crops and buffer strips may also reduce runoff from surface soils.

This is a fixable problem. If people work together to reduce phosphorus pollution, Lake Erie can and will recover. Dr. Jeffrey Reutter

Forty years of water monitoring data has made a huge difference to our understanding of what's happening in Lake Erie, and can help us make smart decisions about the steps we need to take. Senator Randy Gardner

Farmers are ready and willing to do the right thing and USDA is working hard to provide incentives focused on dissolved phosphorus reductions, such as holding back runoff water and better fertilizer management.

Steve Davis

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Forty-five years ago, Lake Erie was so polluted that TIME magazine warned it was "in danger of dying by suffocation." A massive clean-up effort, involving everyone from local businesses to state and national policymakers, brought the lake back from the brink. Recently, algal blooms have once again tainted western Lake Erie with unhealthy, sometimes toxic, green slime.

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Enhanced plant production and improved fish yields are sometimes described as positive impacts of eutrophication, especially in countries where fish and other aquatic organisms are a significant source of food. However detrimental ecological impacts can in turn have other negative consequences and impacts which are described below. Essentially the entire aquatic ecosystem changes with eutrophication. The diagram below gives an overview on the eutrophication process and its causes and consequences.

Ecological impacts

Increased biomass of phytoplankton resulting in algal blooms

Phytoplankton or microalgae are photosynthesizing microscopic organisms. They contain chlorophyll and require sunlight in order to live and grow. Most phytoplankton are buoyant and float in the upper part of the ocean where sunlight penetrates the water. In a balanced ecosystem they provide food for a wide range of organisms such as whales, shrimp, snails and jellyfish. Among the more important groups are the diatoms, cyanobacteria, dinoflagellates and coccolithophores (see: Marine Plankton). Phytoplankton species require inorganic nutrients such as nitrates, phosphates, and sulfur which they convert into proteins, fats and carbohydrates. When too many of these nutrients (by natural or anthropogenic cause) are available in the water phytoplankton may grow and multiply very fast forming algal blooms. Algal blooms may occur in freshwater as well as marine environments. Only one or a small number of phytoplankton species are involved and some blooms discolor (green, yellow-brown or red) the water due to their high density of pigmented cells. Blooms in the ocean may cover a large area and are easily visible in satellite images.

Toxic or inedible phytoplankton species (harmful algal blooms)

Harmful algal blooms (HAB) are bloom events involving toxic or harmful phytoplankton. These cause harm through the production of toxins or by their accumulated biomass, which can effect co-occurring organisms and alter food web dynamics. Impacts include:

Human illness,

Mortality of fish, birds and mammals following consumption or indirect exposure to HAB toxins,

Substantially economic losses to coastal communities and commercial fisheries.

Increased blooms of gelatinous zooplankton

Phytoplankton are the food source for numerous other organisms, especially the zooplankton. Zooplankton are heterotrophic plankton. They are primarily transported by ambient water currents but many have locomotion. Through their consumption and processing of phytoplankton and other food sources they play a role in aquatic food webs as a resource for higher trophic levels including fish. Zooplankton can be divided in two important groups: crustacean (copepods and krill) and gelatinous zooplankton. Gelatinous zooplankton have relatively fragile, plastic gelatinous bodies that contain at least 95% water and which lack rigid skeletal parts. The most well-known are the jellyfish. Eutrophication is believed to cause an increase in the relative importance of gelatinous versus crustacean zooplankton. On many areas of the world where the natural species diversity has been affected by pollution, over-fishing and climate change gelatinous zooplankton organisms may be becoming the dominant species.

Decreases in water transparency (increased turbidity)

The growth of phytoplankton can cause increased turbidity or decreased penetration of light into the lower depths of the water column. In lakes and rivers this can inhibit growth of submerged aquatic plants and affect species which are dependent on them (fish, shellfish).

Dissolved oxygen depletion or hypoxia resulting in increased incidences of fish kills and / or dead benthic animals

Oxygen is required for all life forms on the planet. Oxygen is produced by plants during ( photosynthesis). At night animals and plants, as well as aerobic micro-organisms and decomposing dead organisms respire and so consume oxygen which results in a decrease in dissolved oxygen levels. Large fluctuations in dissolved oxygen levels may be the result of an algal bloom. While the algae population is growing at a fast rate, dissolved oxygen levels decrease. When these algae die, they are decomposed by bacteria which consume oxygen in this process so that the water can become temporarily hypoxic. Oxygen depletion, or hypoxia, is a common effect of eutrophication in water. The direct effects of hypoxia include fish kills, especially the death of fish that need high levels of dissolved oxygen. Changes in fish communities may have an impact on the whole aquatic ecosystem and may deplete fish stocks. In extreme cases hypoxic conditions promote the growth of bacteria that produce toxins deadly to birds and animals. Zones where this occurs are called dead zones.

Species biodiversity decreases and the dominant biota changes

Eutrophication leads to changes in the availability of light and certain nutrients to an ecosystem. This causes shifts in the species composition so that only the more tolerant species survive and new competitive species invade and out-compete original inhabitants. Examples are macroalgae and their massive biomass which inhibits the growth of other aquatic plants and algal blooms that consists of one type of phytoplankton species because other species are expelled.

Increased biomass of macroalgae

Algal blooms may also consist of marine seaweeds or macroalgae. These blooms are recognizable by large blades of algae that may wash up into the shoreline. The seaweed is harmless when it is alive, but when decomposed by anaerobic bacteria toxic gases (such as the colorless hydrogen sulfide (H ₂ S)) can be released.

Human health impacts

Harmful algal bloom species have the capacity to produce toxins dangerous to humans. Algal toxins are observed in marine ecosystems where they can accumulate in shellfish and more generally in seafood reaching dangerous levels for human as well as animal health. Examples include paralytic, neurotoxic and diarrhoeic shellfish poisoning. Several algal species able of producing toxins harmful to human or marine life have been identified in European coastal waters. The table gives an overview of some species that are regularly observed and represent a risk for seafood consumers.

Mental confusion and memory loss, disorientation and sometimes coma

Diatoms of the genus Nitzschia

Shellfish (mussels)

Neurotoxic shellfish p oisoning (NSP)

Muscular paralysis, state of shock and sometimes death

Oysters, clams and crustaceans

Venerupin shellfish p oisoning (VSP)

Gastrointestinal, nervous and hemorrhagic, hepatic symptoms and in extreme causes delirium and hepatic coma

Oysters and clams

Diarrhoeic shellfish p oisoning (DSP)

Gastrointestinal symptoms (diarrhoea, vomiting and abdominal pain)

Filtering shellfish (oysters, mussels and clams)

Paralytic shellfish p oisoning (PSP)

Muscular paralysis, difficulty in breathing, shock and in extreme causes death by respiratory arrest

Oysters, mussels, crustacean and fish

Other marine mammals can be vectors for toxins, as in the case of ciguatera, where it is typically predator fish whose flesh is contaminated with the toxins originally produced by dinoflagellates and then poison humans. Symptoms include gastrointestinal and neurological effects.

Socio-economic impacts

Nearly all of the above described impacts have a direct or indirect socio-economic impact.

Impact on recreation and tourism

The enrichment of nutrients to an ecosystem can result in a massive growth of macroalgae. The existence of such dense algal growth areas can inhibit or prevent access to waterways. This decreases the fitness for use of the water for water sports (swimming, boating and fishing).

Aesthetic impacts

Algal blooms are unsightly and can have unpleasant smells for example:

The appearance of a white yellowish foam on the beach in spring, for example on the shores along the North Sea. The foam is formed by the wind that sweeps up the decaying remains of Phaeocystis algal colonies. An extreme case is shown in Foam beach, Sydney.

When macroalgae or seaweed are decomposed by anaerobic bacteria hydrogen sulfide is (H₂S) released. This gas is characterized by a very unpleasant characteristic foul odor of rotten eggs.

Economical impacts

In some specific cases local authorities must rely on eutrophic waters for production of drinking water. Infected waters increases the costs of water treatment in order to avoid taste, odor and toxin problems in the water. Due to the toxins produced by harmful algal blooms commercial fish and shellfish may become unsuitable for consumption resulting in potential economical and financial problems for the fishing industries. In extreme cases beaches are closed due to the presence of toxic algal blooms.

Related articles

References

1. Eutrophication and health. European Commission (2002). Office for Official Publications of the European Communities: Luxembourg. ISBN 92-894-4413-4.28 pp.

2. The National Eutrophication monitoring Programme Implementation Manual (Murray et al., 2002).

3. Guiry, Michael D. (2013). Nitzschia Hassall, 1845. In: Guiry, M.D. & Guiry, G.M. (2013). AlgaeBase. World-wide electronic publication, National University of Ireland, Galway. Accessed through: World Register of Marine Species at http://www.marinespecies.org/aphia.php?p=taxdetails&id=149045 on 2013-04-22.

4. Guiry, Michael D. (2013). Gymnodinium Stein, 1878. In: Guiry, M.D. & Guiry, G.M. (2013). AlgaeBase. World-wide electronic publication, National University of Ireland, Galway. Accessed through: World Register of Marine Species at http://www.marinespecies.org/aphia.php?p=taxdetails&id=109475 on 2013-04-22.

5. Guiry, Michael D. (2013). Prorocentrum Ehrenberg, 1834. In: Guiry, M.D. & Guiry, G.M. (2013). AlgaeBase. World-wide electronic publication, National University of Ireland, Galway. Accessed through: World Register of Marine Species at http://www.marinespecies.org/aphia.php?p=taxdetails&id=109566 on 2013-04-22.

6. WoRMS (2013). Dinophysis Ehrenberg, 1839. In: Guiry, M.D. & Guiry, G.M. (2013). AlgaeBase. World-wide electronic publication, National University of Ireland, Galway. Accessed through: World Register of Marine Species at http://www.marinespecies.org/aphia.php?p=taxdetails&id=109462 on 2013-04-22.

7. Guiry, Michael D.; Moestrup, Ø. (2013). Alexandrium Halim, 1960. In: Guiry, M.D. & Guiry, G.M. (2013). AlgaeBase. World-wide electronic publication, National University of Ireland, Galway. Accessed through: World Register of Marine Species at http://www.marinespecies.org/aphia.php?p=taxdetails&id=109470 on 2013-04-22.

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Enhanced plant production and improved fish yields are sometimes described as positive impacts of eutrophication, especially in countries where fish and other aquatic organisms are a significant source of food. However detrimental ecological impacts can in turn have other negative consequences and impacts which are described below.

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The chart data is based on 1998 sampling of Buffalo Lake zooplankton. The bars show the mean biomass in micrograms of dry weight per liter arranged by mean size of the individuals of each species population. The sparcity of large zooplankters in Buffalo Lake supports the hypothesis of a strong top-down fish pressure on large zooplankton.

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Nous sommes désolés... Environnement et Changement climatique Canada a transféré son contenu à Canada.ca. Nous vous invitons à consulter les liens suivants : Veuillez mettre à jour vos signets ou liens en conséquence. Vous pouvez également communiquer avec nous en visitant la page Renseignements généraux et Relations avec les médias.

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Effects of Air Pollution (Aniamls & Plants)

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Effects of Air Pollution (Aniamls & Plants)

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Some air pollutants harm plants and animals directly. Other pollutants harm the habitat, food or water that plants and animals need to survive. Read on to learn more about how air pollutants harm plants and animals.

Acid rain harms living things
When acidic air pollutants combine with water droplets in clouds, the water becomes acidic. When those droplets fall to the ground, the acid rain can damage the environment. Damage due to acid rain kills trees and harms animals, fish, and other wildlife. Acid rain can destroy the leaves of plants like in the picture at the left. When acid rain soaks into the ground, it can make the soil an unfit habitat for many living things. Acid rain also changes the chemistry of the water in lakes and streams, harming fish and other aquatic life.

The thinning ozone layer harms living things
Air pollutants called chlorofluorocarbons(or CFCs) have destroyed parts of the ozone layer.The ozone layer, located in the stratosphere layer of Earth's atmosphere, shields our planet from the Sun's ultraviolet radiation. The areas of thin ozone are called ozone holes. Ultraviolet radiation causes skin cancer and damages plants and wildlife.

Tropospheric ozone harms living things
Ozone molecules wind up near the Earth's surface as a part of air pollution. Ozone molecules near the ground damages lung tissues of animals and prevent plant respiration by blocking the openings in leaves where respiration occurs. Without respiration, a plant is not able to photosynthesize at a high rate and so it will not be able to grow.

Global warming harms living things
Our planet is currently warming much more rapidly than expected because additional greenhouse gases are being released into the atmosphere from air pollution. When fuels are burned, some of the pollutants released are greenhouses gases. Through the process of photosynthesis, plants convert carbon dioxide into oxygen and use the carbon to grow larger. However, the amount of carbon dioxide released by burning fuels is much more than plants can convert.

Global warming is causing changes to the places where plants and animals live around the world. For example:

Near the poles, ice and frozen ground are melting. This causes changes in the habitat and resources for plants and animals living there.

Ocean warming, rising sea levels, runoff, and coral diseases are causing change in shallow marine environments such as coral reefs.

Global warming is causing less rain to fall in the middle of continents. This makes these areas very dry and limits water resources for plants and animals.

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Air Pollution Affects Plants, Animals, and Environments

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Some air pollutants harm plants and animals directly. Other pollutants harm the habitat, food or water that plants and animals need to survive. Read on to learn more about how air pollutants harm plants and animals. Acid rain harms living things When acidic air pollutants combine with water droplets in clouds, the water becomes acidic.

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The 1972 Great Lakes Water Quality Agreement

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The 1972 Great Lakes Water Quality Agreement

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Is there something farmers could do to have the greatest impact on improving water quality?

About one-third of Michigan's most productive crop land is tile drained. Tile drains remove excess water.

Eutrophication is the process by which lakes acquire high concentrations of nutrients which promote excessive algae growth. Beginning in the early 1970's, point sources of phosphorus (P) in tributaries to Lake Erie dropped precipitously and there was a continuous improvement in water quality. Since the mid-1990's there has been a clear process of re-eutrophication. Algal biomass has increased in the western and central basins along with water column oxygen demand and total phosphorus concentration. Nonpoint sources now make up the largest, although highly variable, source of total phosphorus.

Dave Baker, Professor Emeritus and founder of the National Center for Water Quality Research (NCWQR) at Heidelberg University in Ohio opened the MI-SWCS conference in East Lansing, A Matter of Balance: Feeding our Crops and Protecting our Water in a Changing Climate with his presentation "Long-Term Trends in Agricultural Runoff to Lake Erie: Causes, Consequences and Remedies." The NCWQR has decades of water quality data gathered at 16 water sampling stations in tributaries in eight agricultural watersheds contributing to the western basin of Lake Erie. Automatic samplers collect water samples every eight hours and each sample is analyzed for at least eleven water quality parameters including total phosphorus (TP), dissolved reactive phosphorus (DRP), various forms of nitrogen and suspended sediment.

Total annual phosphorus loading in Lake Erie is greatly influenced by storm events. Most runoff and nutrient loss occurs from December through March. Water quality monitoring shows that particulate phosphorus has decreased over time, but DRP has increased. This is alarming because DRP stays in the water column and is 100 percent bioavailable for algae and aquatic plants. Particulate phosphorus is linked to erosion and is only about 26 percent bioavailable and tends to settle out of the water column. The reasons for the increase in DRP are not clear.

Various agencies have suggested target load reductions to curtail the hypoxia problem. The current estimate is that DRP in runoff is only about two percent (1.5 pounds per acre-year) of what is applied annually. Farmers are not losing much P but the goal is for a 40 percent reduction in DRP in the western basin and an 80 percent reduction in the central basin. Possible sources include soil P stratification from long-term no-till or reduced tillage, the extensive network of tile drainage throughout the watersheds, changes in soil pH, fall surface broadcast applications of P on agricultural fields, urban point sources and combined sewer over-flows. 'Hot spots,' fields with excessively high soil P test levels could be contributing but there is ample evidence from water quality data that tile drains are also contributing N and DRP. It is also possible that the lake is now more sensitive to DRP loading because of zebra mussel activity and warmer lake temperatures. The solution to the problem is neither simple nor obvious.

As a Michigan State Universy Extenstion educator I asked Dave Baker if there is one or two things farmers could do to have the greatest impact on improving water quality. I thought he might suggest avoiding fall broadcast applications of P fertilizers or some other production practice. Instead, he emphasized the need for continued water quality monitoring, research, and education. Because there are so many potential contributing sources of phosphorus, and losses are so greatly influenced by timing and intensity of rainfall, there really is no single change in production practice that will be most effective every year.
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Is there something farmers could do to have the greatest impact on improving water quality? Eutrophication is the process by which lakes acquire high concentrations of nutrients which promote excessive algae growth. Beginning in the early 1970's, point sources of phosphorus (P) in tributaries to Lake Erie dropped precipitously and there was a continuous improvement in water quality.

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Abstract

In 2011, Lake Erie experienced the largest harmful algal bloom in its recorded history, with a peak intensity over three times greater than any previously observed bloom. Here we show that long-term trends in agricultural practices are consistent with increasing phosphorus loading to the western basin of the lake, and that these trends, coupled with meteorological conditions in spring 2011, produced record-breaking nutrient loads. An extended period of weak lake circulation then led to abnormally long residence times that incubated the bloom, and warm and quiescent conditions after bloom onset allowed algae to remain near the top of the water column and prevented flushing of nutrients from the system. We further find that all of these factors are consistent with expected future conditions. If a scientifically guided management plan to mitigate these impacts is not implemented, we can therefore expect this bloom to be a harbinger of future blooms in Lake Erie.

Results and Discussion

Lake Erie's 2011 algal bloom began in its western basin in mid-July, and estimates from remotely sensed data ( 26) indicate that it covered an area of ∼600 km ² during the initial phase ( Fig. S1). In situ sampling of algal biovolume, areal coverage, and duration indicate that by early September the bloom was at least 2.4 times greater than the previous largest bloom (2008), and four times greater than the average of blooms between 2002 and 2010 ( 14). As Microcystis declined in the western basin in the latter part of the summer, the bloom spread into the central basin, eventually extending 150 km eastward and persisting until mid-October. At its peak in early October, the extent of the bloom was estimated to be more than 5,000 km ² ( 26) ( Fig. S1). The peak bloom intensity, calculated from remote sensing, was 7.3 times greater than the average for the previous 9 years and 3.3 times greater than the previous peak observed in 2008. Cyanobacteria, which were undetectable in June, represented 60-98% of in situ fluorescence measured from surface water throughout the western basin during the bloom.

Taxonomic analysis of the phytoplankton community confirmed that composition was almost entirely Microcystis. Microcystin toxin was detected at most western basin sampling sites with water-column integrated concentrations ranging from 0.1 μg/L to 8.7 μg/L. Surface toxin concentrations could have reached over 4,500 μg/L in early August assuming all Microcystis and microcystin formed a surface scum 10 cm in thickness. The World Health Organization guideline for microcystin in recreational waters is 20 μg/L ( 27), pointing to potential for adverse health effects in 2011. DNA analysis of Microcystis from various locations indicated similar strains in the western and central basins, suggesting that the central basin bloom arose from the eastward migration of Microcystis colonies from the original bloom. As the abundance of the nonnitrogen fixing Microcystis began to decline significantly in the western basin in late August, it was replaced by a secondary bloom of nitrogen-fixing Anabaena sp., suggesting that the Microcystis bloom had largely depleted bioavailable nitrogen in the lake. This was confirmed by in situ sampling of algal nutrient concentrations (SI Materials and Methods and SI Results and Discussion).

Microcystis sp. and Anabaena sp. are both potentially toxic cyanobacteria. Microcystis thrives in Lake Erie, where its growth is stimulated by high concentrations of DRP and combined inorganic nitrogen (i.e., ammonia and nitrate) ( 28). Concentrations of bioavailable phosphorus appear to govern the ultimate biomass of Microcystis, but Lake Erie's low bioavailable nitrogen-to-phosphorus ratio in late summer also provides cyanobacteria, including those that are nonnitrogen fixing, an additional competitive advantage over other phytoplankton classes ( 29⇓ - 31). Temperature and mixing conditions are also important in determining growth, because cyanobacteria have a higher temperature optimum (on the order of 25 °C) than eukaryotic phytoplankton ( 17, 32), and temperature-dependent gas vacuoles increase Microcystis buoyancy, allowing them to rise to more favorable light and temperature conditions under quiescent conditions ( 33).

We hypothesize that trends in agricultural land use contributed to the 2011 bloom. Corn cropland increased 11% nationally and land in the federal Conservation Reserve Program (CRP) decreased 14% between 2008 and 2011 ( Fig. S2). Similar trends in the western Lake Erie watershed could lead to increased phosphate fertilizer use, because phosphate is applied to corn at a 36% higher rate than to soybeans in Ohio (SI Materials and Methods and SI Results and Discussion), and because the conversion of CRP land to agriculture would also substantially increase phosphate use. Together, these could result in greater phosphorus runoff and higher loadings in western Lake Erie. However, trends in the Lake Erie watershed deviate sharply from those national trends. Both corn cropland and CRP land changed only slightly from 2008 to 2011 (SI Materials and Methods, SI Results and Discussion, and Fig. S2). It is therefore unlikely that recent agricultural land use trends are important drivers of the 2011 bloom.

Long-term trends in agricultural nutrient management practices, on the other hand, are consistent with a potential for higher nutrient loading ( Table S1). Three management practices-autumn fertilizer application, fertilizer being broadcast on the surface rather than injected in the soil, and conservation tillage-can create conditions for enhanced DRP runoff. These practices have increased in the region over the last 10 y, although in some cases evidence is only anecdotal. Consistent with these trends is the observed 218% increase in DRP loadings between 1995 and 2011 ( P = 0.0004) from the Maumee River, the main tributary to the western basin, whereas runoff increased by only 42% ( P = 0.12) over the same period (SI Materials and Methods, SI Results and Discussion and Table S2).

Autumn weather conditions in 2010 were ideal for completing harvest and preparing fields for the following year, increasing autumn application of fertilizer. The spring of 2011 then experienced a series of large storm runoff events between February 17 and June 8, including a major event with peak daily mean discharge exceeding 2,200 m ³/s on May 25-27 (SI Materials and Methods and SI Results and Discussion and Fig. 2A). This storm represents the 99.8th percentile for Maumee daily discharge since 1975, when intensive monitoring of this tributary began. During this peak event, convective cells originated from a low-pressure system centered over the southern Great Plains and propagated to the north and east over a 2-d period ( Fig. S3). The peak 24-h accumulated precipitation exceeded 50 mm over the Maumee River basin on May 26, contributing to a total of over 170 mm of rain in May 2011. This is over 75% above the prior 20-y average for May (97 mm averaged over 1986-2005). Total discharge and phosphorus loads for the 111-d (February 17 to June 8) and 15-d (May 25 to June 8) periods covering the springtime precipitation events ( Fig. S4) are among the largest observed since 1975, for periods of those lengths. Similarly, total discharge and DRP loads during the March-to-June timeframe, which is the critical period for setting up algal blooms ( 26), were the largest since intensive monitoring began in 1975. This is in stark contrast to these months in 2012, when discharge from the Maumee was only 20% and DRP loading was 15% of 2011 values.

We use the Soil and Water Assessment Tool (SWAT) model ( 34, 35) to test the impact of precipitation intensity and agricultural nutrient management practices on expected nutrient loading, to determine whether these factors are likely to be responsible for the loading observed in 2011. SWAT simulations indicate that DRP yields are sensitive to precipitation intensity (higher intensity increasing yields, Fig. 2B), fertilizer application timing (proximity to storm events increasing DRP yields, Fig. 2 A and B), and tillage practices (no-till increasing DRP yields, Fig. 2B), with precipitation having the strongest influence and fertilizer timing having the least influence (SI Materials and Methods and SI Results and Discussion). This supports the hypothesis that the confluence of long-term trends in agricultural nutrient management practices and extreme precipitation events was a strong contributor to the DRP yields that triggered the 2011 bloom.

We also hypothesize that temperature and wind conditions over the lake both before and during the bloom encouraged bloom growth, because warm and quiescent conditions before bloom onset led to minimal flushing of the system and reduced vertical lake mixing that allows Microcystis to take advantage of its buoyancy regulation. However, wind and surface water temperature data from the lake buoy indicate a lower frequency of warm and quiescent conditions during the 2011 prebloom period (defined as daily average wind stress τ < 0.05 Pa and temperature T > 15 °C) ( 36) relative to other bloom years (SI Materials and Methods and SI Results and Discussion). In addition, although a particularly strong wind-driven resuspension event before the bloom onset could encourage fast initial bloom growth, wind conditions that led to the resuspension event immediately preceding bloom onset were not unusual relative to other years. After bloom initiation, on the other hand, conditions were indeed more conducive to bloom growth relative to other years, as quantified by the percent of time under warm and quiescent conditions after bloom onset (62% relative to 35-56% in other years, P = 0.015). These buoy-based observations are consistent with satellite-derived lake temperatures that were 3 °C warmer than the 1992-2011 summer climatology and 1 °C warmer than 2010 temperatures (SI Materials and Methods, SI Results and Discussion, and Fig. S5).

To investigate the role of lake circulation in encouraging the bloom, we apply 3D hydrodynamic and particle transport models (SI Materials and Methods and SI Results and Discussion). Simulations show that western basin monthly circulation is characterized by a broad west-east flow that exits the basin via three channels (North, Middle, and South), with low current magnitudes correlated with increased residence times ( Fig. 3). All simulated years exhibit relatively low-magnitude currents during summer months (May-August), but 2011 had an extended period with weak currents (consistent with weaker winds) from late winter through summer (February-July) ( Fig. S6). The residence times in the western basin during this period were 46% and 36% longer than in the previous years (2009 and 2010, respectively). Furthermore, residence times of Maumee River water in June 2011 were 53% longer than in the previous years and 77% longer (>90 d) than the estimated mean hydraulic residence time of the western basin ( Fig. S7). Simulations also show that the long residence times were accompanied by a "short circuiting" of Detroit River waters, leading to minimal mixing between the Detroit and Maumee River waters along the western and southern shores of the basin, thus diminishing dilution of nutrient-rich Maumee River waters. Although some mixing occurs near the islands between the western and central basins during April-August, Detroit and Maumee waters primarily leave the western basin through the North and Middle/South Channels, respectively ( Fig. S8). Location and timing of bloom initiation is consistent with simulated advection of the elevated late spring Maumee runoff, suggesting that the water mass present at the first stages of the bloom initiation likely originated from the Maumee River close to June 1.

Of the original hypothesized causes of the monumental 2011 bloom, observations and simulations therefore confirm that long-term trends in agricultural practices are consistent with increasing DRP loads delivered to the western basin of Lake Erie, and that meteorological conditions in spring 2011 led to record-breaking nutrient loads to the lake during the late spring. This conclusion is further supported by substantially lower discharge in 2012 leading to lower DRP loading and a weaker bloom ( 37). Our results further show that weak circulation during summer 2011 led to longer residence times that incubated the bloom, and that warm and quiescent lake conditions after bloom onset allowed Microcystis to remain near the top of the water column and prevented flushing of nutrients out of the system. Conversely, data do not support the hypothesis that recent land use and crop choice trends in the watershed contributed to the observed significant increase in the 2011 nutrient loading. In addition, observations show that lake conditions were not unusually warm and quiescent before bloom onset, and the resuspension event immediately preceding the bloom was not of unusual magnitude. Overall, the magnitude of the 2011 bloom was thus caused by a confluence of long-term trends in agricultural nutrient management and extreme meteorological events conducive to bloom formation.

The degree to which the 2011 bloom is a harbinger of future conditions depends on the likelihood of these long-term agricultural trends continuing, and the likelihood of an increased frequency of meteorological conditions such as those observed in 2011.

Lacking policy intervention, many of the socioeconomic forces driving the trends in agriculture and nutrient management practices found to have exacerbated the 2011 bloom are likely to continue, increasing the likelihood of such massive blooms in the future. Factors such as increasing fertilizer costs, however, may provide some economic constraints. Furthermore, although crop choice was not found to have been a contributing factor in 2011, 2012 showed a marked increase in fertilizer-intensive corn acreage in the region (15% increase in Ohio; 4% increase in Michigan) ( 38). Nationally, planted corn acres were higher than a recent spike in 2007 and the highest since 1937, driven in large part by the high prices for corn resulting from biofuel policy ( 39). In addition, prospective changes to the CRP would lead to higher land use by agriculture overall (SI Materials and Methods and SI Results and Discussion). If the 2012 corn acreage is indicative of the future-and policies mandating higher biofuel production and lower CRP acres suggest that it is-then this trend will add to those trends found to have been significant in the 2011 loads.

To determine if precipitation events such as those observed in spring 2011 are more likely to occur in the future, we evaluate spring (March-April-May) daily precipitation over the western Lake Erie basin from 12 Climate Model Intercomparison Project Phase 5 (CMIP5) climate models implementing the Representative Concentration Pathway 8.5 (RCP8.5) scenario (SI Materials and Methods, SI Results and Discussion, and Table S3) ( 40). The historical (1986-2005) CMIP5 simulations over the western basin overpredict the current frequency of events >10 mm ( Fig. 4) and overestimate the current average springtime precipitation intensity by 30%. Despite this overprediction of the historical period, prior CMIP3 studies have shown that climate model simulations of large scale (>1,000 km) flow patterns can reliably reproduce observations, and multimodel predictions of increased future precipitation intensity are statistically significant ( 41). Under the future RCP8.5 scenario, the frequency of events of >20 mm, which have an approximately annual recurrence interval based on the observational record, increases by ∼50%, and the frequency of larger storms increases even more, with events >30 mm being twice as frequent. This suggests a potentially even greater increase in the frequency of occurrence of the largest storms, such as the one observed in 2011.

Weak lake circulation and quiescent conditions after bloom onset, as observed in 2011, are also consistent with observed trends of decreasing wind speeds over the continental United States ( 42) and elsewhere ( 43), suggesting that the long residence times and quiescent conditions observed in 2011 may not be uncommon in the future. A continuing trend toward lower wind speeds would contribute to the severity of blooms, both through increasing residence times and decreased mixing in the water column.

In summary, we find that trends in agricultural practices, increased precipitation, weak lake circulation, and quiescent conditions conspired to yield the record-breaking 2011 Lake Erie algal bloom. We further find that all of these factors are consistent with expected future conditions. Lacking the implementation of a scientifically guided management plan designed to mitigate these impacts, we can therefore expect this bloom to indeed be a harbinger of future blooms in Lake Erie.

Materials and Methods

Microcystis biovolume and nutrient concentrations were determined at fixed locations in western Lake Erie, and molecular fingerprints were used to analyze Microcystis populations. Data on land use, county-level CRP land area, and crop-level phosphate fertilizer application were obtained from the US Department of Agriculture. Additional county-level nutrient use data were obtained from the Nutrient Use Geographic Information System. Meteorological analysis used data from the University Corporation for Atmospheric Research image archive and the College of DuPage. Daily precipitation observations were obtained from National Oceanic and Atmospheric Administration (NOAA) Climate Prediction Center. Analysis of discharge and phosphorus loading were based on data from the National Center for Water Quality Research at Heidelberg University and flow data from the US Geological Survey. The SWAT model was used to model nutrient loading. Lake Erie wind and temperature data were obtained from the NOAA National Data Buoy Center, and remote sensing lake surface temperature data were obtained from NOAA CoastWatch. Hydrodynamic modeling was conducted using the Beletsky and Schwab model and a particle tracking code was used for residence time calculations and river plume tracking. Present-day and future climate model analyses were based on the CMIP5 data archive. Detailed materials and methods, and references, are available in SI Materials and Methods. Information on data availability is provided in SI Materials and Methods and SI Results and Discussion.

Acknowledgments

The authors thank Raisa Beletsky, Greg Lang, and David Schwab, who provided modeling support and Todd Marsee for assistance with graphic design. We acknowledge the World Climate Research Programme's Working Group on Coupled Modelling, which is responsible for the Climate Model Intercomparison Project (CMIP), and we thank the climate modeling groups (listed in Table S3 of this paper) for producing and making available their model output. This material is based upon work supported by the National Science Foundation (NSF) under Grants 1039043 and 1313897. Additional support was provided by NSF Grant 0927643 (to D.B.) and the National Oceanic and Atmospheric Administration Center for Sponsored Coastal Ocean Research Grant NA07OAR432000 (to D.B., N.S.B., R.P.R., and D.S.). Support was provided by Lake Erie Protection Fund SG 406-2011 (to J.D.C. and T.B.B.). For CMIP, the US Department of Energy's Program for Climate Model Diagnosis and Intercomparison provided coordinating support and led development of software infrastructure in partnership with the Global Organization for Earth System Science Portals. This paper is Ecofore Lake Erie Contribution Number 12-009 and Great Lakes Environmental Research Laboratory Contribution Number 1646, and Lake Erie Center Contribution Number 2013-09.

Footnotes

Author contributions: A.M.M., E.J.A., D.B., N.S.B., T.B.B., R.C., J.V.D., J.C.H., M. R. Moore, D.J.P., R.P.R., D.S., and A.L.S. designed research; A.M.M., E.J.A., D.B., S.B., N.S.B., T.B.B., J.D.C., K.C., R.C., I.D., M.A.E., G.L.F., L.H., J.C.H., L.J., T.H.J., K.C.K., X.L., M. R. McWilliams, M. R. Moore, D.J.P., R.P.R., D.S., A.L.S., D.M.W., and M.A.Z. performed research; A.M.M., E.J.A., D.B., S.B., N.S.B., T.B.B., J.D.C., K.C., R.C., I.D., J.V.D., M.A.E., L.H., J.C.H., L.J., T.H.J., K.C.K., X.L., M. R. McWilliams, M. R. Moore, D.J.P., R.P.R., D.S., A.L.S., E.V., D.M.W., and M.A.Z. analyzed data; and A.M.M., E.J.A., D.B., N.S.B., T.B.B., J.D.C., K.C., I.D., J.V.D., M.A.E., J.C.H., T.H.J., E.L., M. R. McWilliams, M. R. Moore, D.J.P., R.P.R., D.S., and A.L.S. wrote the paper.

The authors declare no conflict of interest.

This article is a PNAS Direct Submission. R.E.H. is a guest editor invited by the Editorial Board.

This article contains supporting information online at www.pnas.org/lookup/suppl/doi:10.1073/pnas.1216006110/-/DCSupplemental.

Freely available online through the PNAS open access option.

View Abstract

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Record-setting algal bloom in Lake Erie caused by agricultural and meteorological trends consistent with expected future conditions

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In 2011, Lake Erie experienced the largest harmful algal bloom in its recorded history, with a peak intensity over three times greater than any previously observed bloom. Here we show that long-term trends in agricultural practices are consistent with increasing phosphorus loading to the western basin of the lake, and that these trends, coupled with meteorological conditions in spring 2011, produced record-breaking nutrient loads.

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Eutrophication is the process in which lakes receive nutrients (phosphorus and nitrogen) and sediment from the surrounding watershed and become more fertile and shallow. Eutrophication can be slowed by reducing nutrient and sediment addition to the lake. It is nearly impossible to turn a eutrophic lake back into an oligotrophic lake, but it is possible to turn back eutrophication somewhat.
Reducing Nutrient Addition
Since phosphorus is the main cause of eutrophication in most Minnesota lakes, reducing phosphorus addition to the lake is the most effective way to slow eutrophication. Phosphorus can enter a lake through poorly managed or failing septic systems, phosphorus detergents, phosphorus lawn fertilizers, agriculture, and animal feedlots. To locate the source of eutrophication for a specific lake, complete a ground truthing study and a lakeshore inventory. A ground truthing study involves inspecting the inlets to the lake and identifying any sources of phosphorus along them that is adding nutrients to the stream and then eventually the lake. A lakeshore inventory involves driving a boat slowly around the whole shore of the lake, taking a photo of each parcel and evaluating land management practices. The parcels on the lake can be summarized by percentages; for example, 60% of the parcels have proper shoreline vegetation buffers and 40% do not. Educating lakeshore property owners on how to limit phosphorus addition to the lake is paramount.
Reducing Sediment Addition
When erosion occurs along a lakeshore or a stream bank of a lake inlet, that extra soil can get washed into the lake. The extra soil particles cause cloudier water and eventually settle on the bottom of the lake making it mucky and less stable. The soil also carries with it nutrients such as phosphorus and nitrogen which can cause algal blooms. During a groundtruthing study and lakeshore inventory, note the areas where erosion is occurring and take steps to stabilize the area. The most effective stabilization technique is a shoreline buffer of native plants; however, on very steep shores where plants wouldn't establish riprap can be effective (more information on shorline buffers and restoration).

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How can Eutrophication be slowed? - RMBEL

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Eutrophication is the process in which lakes receive nutrients (phosphorus and nitrogen) and sediment from the surrounding watershed and become more fertile and shallow. Eutrophication can be slowed by reducing nutrient and sediment addition to the lake. It is nearly impossible to turn a eutrophic lake back into an oligotrophic lake, but it is possible to turn back eutrophication somewhat.

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With the GMO debate far from over, we asked Mark Hughes, President, Anderson Partners Food Ingredient Marketing for an insight into why the conversation still matters...

With the GMO debate far from over, we asked Mark Hughes, President, Anderson Partners Food Ingredient Marketing for an insight into why the conversation still matters...

Many major food manufacturers including General Mills, ConAgra Foods and Campbell's have announced over the past year that they will begin labelling their products to state that they contain GMOs or genetically engineered ingredients.

While all of these companies have stated unequivocally that they agree with the scientific consensus that GMO foods are safe, they have been forced to start labelling their products to comply with new labelling regulations.

The regulations call for a simple statement in the ingredient label on the back of the package instead of the "skull and crossbones" negative warning symbol many anti-GMO advocates had been hoping for. Many of these same anti-GMO advocates have been claiming victory in the debate over GMOs while, in fact, well over 90% of all packaged foods sold in the U.S. will continue to contain some level of genetically engineered ingredients.

In this overheated and passionate environment, what should responsible leaders in the food science community think about the continuing debate over GMO technologies? Even though packaged food products will begin labelling the inclusion of GMO ingredients, the science behind GMO technologies will continue to play a crucial role in the evolving future of food. The food science community needs to have a clear and common sense position supporting the scientific consensus behind the importance of these technologies.

In thinking about this position, it is helpful to view the GMO debate through the lenses of the "Rich World" and the "Poor World." In the "Rich World," consumers are able to make "lifestyle choices" about the foods that they eat. Many "Rich World" consumers can afford to pay the increased costs associated with organic, natural and non-GMO food choices. They can make these types of "personal fashion statements" about the foods they choose to buy and eat.

"We need GMO technologies in order to meet the increased demand of food production..."

In the "Poor World," the least-developed countries around the globe, consumers are often simply trying to find enough food to feed themselves and their families. They cannot afford the kind of fashionable food choices that consumers in the "Rich World" are able to make.

It is in these developing countries where the benefits of GMO technologies are needed most to increase crop yields, adapt for climate change and provide proper nutrition. The United Nations estimates that world population will expand to over 9 billion people by 2050 and that the vast majority of that population growth will take place in the least-developed countries of the world.

Over 90% of all packaged foods sold in the U.S. will continue to contain some level of genetically engineered ingredients...

We need GMO technologies in order to meet the increased demand of food production required to feed this rapidly growing global population. GMO technologies and GMO scientists can help us feed the world, if we let them. The food science community needs to take the lead in advocating for the sensible development of advanced GMO technologies. We should support scientifically sound GMO practices and take the initiative to communicate the food science position to help educate consumers in the U.S. and worldwide. And we can do all this while still supporting openness and transparency across the food industry.

In the final analysis, feeding a rapidly growing world population is the "Grand Challenge" of our generation and the real goal of the evolving future of food. As Newsweek magazine recently said:

"If we can't feed the world, it will eventually feed on us."

It is clear that the GMO debate will not be going away anytime soon and it will be interesting to monitor its development in the wake of Trump's election, particularly with respect to regulation.

________________________________

Mark Hughes is a leading expert in global food ingredient marketing and a recognised thought leader in new communication models. His firm, Anderson Partners Food Ingredient Marketing, works with major ingredient marketers like Chiquita Brands, ConAgra Foods, Ardent Mills and Land O'Lakes Global Dairy Ingredients.

Hughes is an active member of the Institute of Food Technologists (IFT) where he serves on the IFT's Scientific Program Advisory Panel and on the leadership committee of the IFT's Marketing & Management Division. He is a long time member of the Research Chefs Association (RCA) and was elected to the RCA Board of Directors in 2016.

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Why the GMO debate still matters - New Food Magazine

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With the GMO debate far from over, we asked Mark Hughes, President, Anderson Partners Food Ingredient Marketing for an insight into why the conversation still matters... With the GMO debate far from over, we asked Mark Hughes, President, Anderson Partners Food Ingredient Marketing for an insight into why the conversation still matters...

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1. GMOs are unhealthy.
The American Academy of Environmental Medicine (AAEM) urges doctors to prescribe non-GMO diets for all patients. They cite animal studies showing organ damage, gastrointestinal and immune system disorders, accelerated aging, and infertility. Human studies show how genetically modified (GM) food can leave material behind inside us, possibly causing long-term problems. Genes inserted into GM soy, for example, can transfer into the DNA of bacteria living inside us, and that the toxic insecticide produced by GM corn was found in the blood of pregnant women and their unborn fetuses.

Numerous health problems increased after GMOs were introduced in 1996. The percentage of Americans with three or more chronic illnesses jumped from 7% to 13% in just 9 years; food allergies skyrocketed, and disorders such as autism, reproductive disorders, digestive problems, and others are on the rise. Although there is not sufficient research to confirm that GMOs are a contributing factor, doctors groups such as the AAEM tell us not to wait before we start protecting ourselves, and especially our children who are most at risk.

The American Public Health Association and American Nurses Association are among many medical groups that condemn the use of GM bovine growth hormone, because the milk from treated cows has more of the hormone IGF-1 (insulin-like growth factor 1)―which is linked to cancer.

2. GMOs contaminate―forever.
GMOs cross pollinate and their seeds can travel. It is impossible to fully clean up our contaminated gene pool. Self-propagating GMO pollution will outlast the effects of global warming and nuclear waste. The potential impact is huge, threatening the health of future generations. GMO contamination has also caused economic losses for organic and non-GMO farmers who often struggle to keep their crops pure.

3. GMOs increase herbicide use.
Most GM crops are engineered to be "herbicide tolerant"―they deadly weed killer. Monsanto, for example, sells Roundup Ready crops, designed to survive applications of their Roundup herbicide.

Between 1996 and 2008, US farmers sprayed an extra 383 million pounds of herbicide on GMOs. Overuse of Roundup results in "superweeds," resistant to the herbicide. This is causing farmers to use even more toxic herbicides every year. Not only does this create environmental harm, GM foods contain higher residues of toxic herbicides. Roundup, for example, is linked with sterility, hormone disruption, birth defects, and cancer.

4. Genetic engineering creates dangerous side effects.
By mixing genes from totally unrelated species, genetic engineering unleashes a host of unpredictable side effects. Moreover, irrespective of the type of genes that are inserted, the very process of creating a GM plant can result in massive collateral damage that produces new toxins, allergens, carcinogens, and nutritional deficiencies.

5. Government oversight is dangerously lax.
Most of the health and environmental risks of GMOs are ignored by governments' superficial regulations and safety assessments. The reason for this tragedy is largely political. The US Food and Drug Administration (FDA), for example, doesn't require a single safety study, does not mandate labeling of GMOs, and allows companies to put their GM foods onto the market without even notifying the agency. Their justification was the claim that they had no information showing that GM foods were substantially different. But this was a lie. Secret agency memos made public by a lawsuit show that the overwhelming consensus even among the FDA's own scientists was that GMOs can create unpredictable, hard-to-detect side effects. They urged long-term safety studies. But the White House had instructed the FDA to promote biotechnology, and the agency official in charge of policy was Michael Taylor, Monsanto's former attorney, later their vice president. He's now the US Food Safety Czar.

6. The biotech industry uses "tobacco science" to claim product safety.
Biotech companies like Monsanto told us that Agent Orange, PCBs, and DDT were safe. They are now using the same type of superficial, rigged research to try and convince us that GMOs are safe. Independent scientists, however, have caught the spin-masters red-handed, demonstrating without doubt how industry-funded research is designed to avoid finding problems, and how adverse findings are distorted or denied.

7. Independent research and reporting is attacked and suppressed.
Scientists who discover problems with GMOs have been attacked, gagged, fired, threatened, and denied funding. The journal Nature acknowledged that a "large block of scientists . . . denigrate research by other legitimate scientists in a knee-jerk, partisan, emotional way that is not helpful in advancing knowledge." Attempts by media to expose problems are also often censored.

8. GMOs harm the environment.
GM crops and their associated herbicides can harm birds, insects, amphibians, marine ecosystems, and soil organisms. They reduce bio-diversity, pollute water resources, and are unsustainable. For example, GM crops are eliminating habitat for monarch butterflies, whose populations are down 50% in the US. Roundup herbicide has been shown to cause birth defects in amphibians, embryonic deaths and endocrine disruptions, and organ damage in animals even at very low doses. GM canola has been found growing wild in North Dakota and California, threatening to pass on its herbicide tolerant genes on to weeds.

9. GMOs do not increase yields, and work against feeding a hungry world.
Whereas sustainable non-GMO agricultural methods used in developing countries have conclusively resulted in yield increases of 79% and higher, GMOs do not, on average, increase yields at all. This was evident in the Union of Concerned Scientists' 2009 report Failure to Yield―the definitive study to date on GM crops and yield.

The International Assessment of Agricultural Knowledge, Science and Technology for Development (IAASTD) report, authored by more than 400 scientists and backed by 58 governments, stated that GM crop yields were "highly variable" and in some cases, "yields declined." The report noted, "Assessment of the technology lags behind its development, information is anecdotal and contradictory, and uncertainty about possible benefits and damage is unavoidable." They determined that the current GMOs have nothing to offer the goals of reducing hunger and poverty, improving nutrition, health and rural livelihoods, and facilitating social and environmental sustainability.
On the contrary, GMOs divert money and resources that would otherwise be spent on more safe, reliable, and appropriate technologies.

10. By avoiding GMOs, you contribute to the coming tipping point of consumer rejection, forcing them out of our food supply.
Because GMOs give no consumer benefits, if even a small percentage of us start rejecting brands that contain them, GM ingredients will become a marketing liability. Food companies will kick them out. In Europe, for example, the tipping point was achieved in 1999, just after a high profile GMO safety scandal hit the papers and alerted citizens to the potential dangers. In the US, a consumer rebellion against GM bovine growth hormone has also reached a tipping point, kicked the cow drug out of dairy products by Wal-Mart, Starbucks, Dannon, Yoplait, and most of America's dairies.

NOTE: As an additional motivation to avoid GMOs, you may wish to take a lesson from the animals. Eyewitness reports from around the world describe several situations where animals, when given a choice, avoid genetically modified food. These include cows, pigs, geese, elk, deer, raccoons, mice, rats, squirrels, chicken, and buffalo. We're pretty sure the animals didn't read the above 10 reasons.

The Campaign for Healthier Eating in America is designed to achieve a tipping point against GMOs in the US. The number of non-GMO shoppers needed is probably just 5% of the population. The key is to educate consumers about the documented health dangers and provide a Non-GMO Shopping Guide to make avoiding GMOs much easier.
Please choose healthier non-GMO brands, tell others about GMOs so they can do the same, and join the Non-GMO Tipping Point Network. Together we can quickly reclaim a non-GMO food supply.

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10 Reasons to Avoid GMOs - Institute for Responsible Technology

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1. GMOs are unhealthy. The American Academy of Environmental Medicine (AAEM) urges doctors to prescribe non-GMO diets for all patients. They cite animal studies showing organ damage, gastrointestinal and immune system disorders, accelerated aging, and infertility. Human studies show how genetically modified (GM) food can leave material behind inside us, possibly causing long-term problems. Genes ...

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What is a GMO? Under the Non-GMO Project Standard, a genetically modified organism (GMO) is an organism to which biotechnology has been applied. This creates combinations of plant, animal, bacteria and virus genes that do not occur in nature or through traditional crossbreeding methods. Are GMOs safe?

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POACHING. The "moist heat" technique of poaching was very much a part of the recorded recipes of the ancient world. In one of the earliest cookbooks, the Roman Apicius's De re Coquinaria, recipes for delicacies like Isicia Plena (Dumplings of Pheasant) show that stiff forcemeat dumplings were poached in water seasoned with garum. And certain other savory and sweet recipes, like Aliter Patina Versatilis (A Nut Custard), instructed cooks to pour custard into molds to be placed into pans partially filled with hot water. After the invention of the printing press and the appearance of the first printed cookbook, Le viandier (1490), by the Frenchman Taillevent, the various aspects of poaching found a broader audience. However, it was not until the seventeenth century and the ever-increasing management of fire that poaching as a culinary technique gained in popularity. In 1651, with the printing of original cookbooks in addition to the collected works of the past, recipes began to integrate a repertory of techniques, basic mixtures, and raw materials. Lightly cooking certain ingredients in a small amount of liquid was not only part of a process of making a certain dish, but it also opened the possibility of refining the dish with savory sauces.

When Charles Ranhofer, chef of the famous New York establishment Delmonico's, published The Epicurean in 1893, various poached egg, seafood, and chicken dishes were featured as sophisticated menu offerings. Ten years later in his monumental cookbook Ma Cuisine, Georges-Auguste Escoffier listed 141 variations for along with fifteen more recipes for cold preparations including and chaud froid dishes. And when Prosper Montagn published Larousse Gastronomique in 1938, he provided the formulas for several poached egg dishes beginning with oeufs Aladin (poached eggs on a mound of saffron risotto, garnished with sweet peppers, and napped with tomato sauce) and ending with (poached eggs placed on oval fried croutons covered with thin slices of ham, and coated with Zingara sauce, a tomato-flavored demi-glace with a julienne of ham, tongue, and mushrooms). The same sophistication in the utilization of poached fish and poultry could be seen in recipes for filets de soles la normande and And with the advent of nouvelle cuisine and especially cuisine minceur (calorie-defused dishes developed by the French chef Michel Guerard) in the 1960s, poaching various ingredients in flavorful liquids and substituting innovative vegetable and herb pures for sauces canonized the technique of poaching as a healthy trend.

In comparing the various examples of "moist heat" cooking, the amount of liquid, the timing, and the temperature are distinguishing factors. In poaching, the item to be cooked is generally submerged entirely in liquid, except in shallow poaching, when the item is only partially submerged in liquid and loosely covered with parchment paper. Timing is critical and depends on the size, density, and ripeness of the item to be cooked. The temperature for poaching registers between 160 and 180F (7182C), and should always be maintained lower than a simmer (185F [85C]) to guarantee tenderness.

Although plain water or salt and vinegar-infused water is used in poaching, the liquids more frequently utilized in this cooking method are usually more flavorful. Stock, court bouillon, vegetable juice, vermouth, and various aromatics, such as herbs, spices, and citrus zest, contribute to the taste of the item cooked and also serve as the basis for a congenial sauce to nap the prepared poached fish, poultry, vegetable, fruit, or meat.

Unlike boiling, which requires only water, a pottery or metal pot, and heat to perform, poaching has acquired through the years a distinctive batterie de cuisine. An oblong covered pan called a poacher with handles at both ends and a convenient rack for lifting the prepared item from the pan greatly facilitates cooking a large fish. Egg poachers feature an insert with a specified number of round or oval, often perforated, cups to submerge eggs in a pan of water. Also used are metal rings that contain the entire egg when it is slipped into the water. A specific kind of shallow skillet with sloping sides called a sauteuse is used for poaching smaller items. And to insure even cooking and avoid curdling, various custards, timbales, and terrines are poached in their containers in a bain-marie, or water bath.

Poached Eggs

Instructions for poaching eggs are varied, many, and often contradictory. Some directions, for instance, recommend adding salt or vinegar to the poaching water; some call for breaking eggs into a saucer before lowering into the water; others for boiling eggs in the shell for ten seconds before breaking and poaching in water; still others for creating a whirlpool in the center of the pan and dropping each egg into it individually; and others for removing eggs and trimming them to the desired oval shape before serving.

The use of salt is debatable, although some chefs suggest that it speeds up the cooking process. Vinegar and acids, like lemon juice and wine, denature the proteins in egg whites and should be added to the poaching water. Breaking the egg into and as close to the poaching water as possible is the direct approach, but some cooks prefer the perforated cup method. Without exception, however, recipes for poached eggs advocate the use of the freshest eggs possible because the yolk membrane will still be strong, and the egg white will cling firmly to the yolk in a mass and not trail off in feathers. The older the egg, the looser the white becomes.Timing in poaching depends on the size and grade (Grade AA is preferable) of the egg, and the temperature of the poaching liquid. Some cooks suggest immersing in lightly boiling water and then, when the whites begin to set, reducing the water temperature to 175F (79C) or covering the pan and removing it from the heat. Cooking for too long a period of time, or with too hot a temperature, toughens the proteins. So attention to cooking time and water temperature is necessary, especially if the eggs are to be stored in fresh cold water for use later.

Recipes for poached eggs appear in almost every cookbook either as comforting food pour un malade, a display of the skill and inventiveness of the cook, or a staple of the breakfast/brunch buffet. Many distinctive dishes also are garnished with a poached egg, including the traditional veal cutlet dish Wiener schnitzel; the famous curly endive and lardon salad of Lyon, France; the American breakfast steak; and corned beef hash. In 1861, the Englishwoman Isabella Beeton suggested serving poached eggs on toasted bread or on slices of ham or bacon in her Book of Household Management. A hundred years later, avoiding what she called "that sodden toast," in French Country Cooking (1959), Elizabeth David recommended serving a poached egg on a pure of split peas, corn, or mushrooms, with fried bread on the side. And she included a traditional recipe for oeufs Benedictine, in which poached eggs are placed on a bed of creamed salt cod in individual flat dishes and napped with Hollandaise sauce. In Simple French Food (1975), an avid American practitioner of French cooking, Richard Olney, recommends preparing poached eggs and placing them in artichoke bottoms, topped with Mornay (cheese) sauce and surrounded by a julienne of lightly blanched vegetables (p. 101).

In the United States, serving poached eggs on a piece of toast covered with a slice of ham and napped with Hollandaise sauce translated into an American idiom when it was named after a Wall Street stockbroker (the term appeared in print for the first time in 1928). Lemuel Benedict reputedly used poached eggs, toast, and bacon sauced in Hollandaise as a cure for the extravagances of the "night before." In time Oscar Tschirky, matre d'htel of the Waldorf-Astoria hotel in New York, refined the dish by substituting toasted English muffins and ham for the toast and bacon, and by adding shaved truffles. Eggs Benedict was also served at Delmonico's restaurant in New York. The dish has not gone out of favor, but has been enhanced by many variations on the basic theme of a poached egg, toast, ham, and sauce blanche.

From the breakfast and brunch table to the buffet, chefs have devised multiple variations of , or cold poached eggs in jelly. Time-consuming but easy to make, jellied consomm or aspic is systematically added to a mold holding a poached egg and various garnishes until the mold is filled. After the final setting of the jelly, it is unmolded, and served.

Poached Seafood

Poaching is an ideal way to cook a large fish because no fat is used. The skin can be easily removed, and the delicate flavor and texture of the fish is preserved. The cooking process begins in cold liquid, usually a court bouillon (vegetable broth and wine) and is maintained at 176F (80C). If a fish poacher is too large, small whole fish, fillets, and steaks are usually wrapped in cheesecloth for easy removal and poached in any pan large enough to hold sufficient liquid to cover the fish. Some cookbooks also suggest poaching delicate fillets in melted butter in an enclosed casserole, but rather than poaching, the French call this technique .

Because the poaching liquid is both flavorful and acidic, reduction and emulsified sauces can be made to nap the fish, however, the glories of French cuisine have been more traditionally displayed in the repertory of elaborate saucesBlanche, Bordelaise, Diplomat, Dauphin, and Hollandaisefrequently prescribed for fish.

Delicate shellfish like scallops, oysters, and shrimp can also be poached in wine, aromatics, or in their own liquor. And seafood mousses in various-sized porcelain molds are always poached either on top of the stove or in the oven in a pan half-filled with water at 176F (80C).

Poached Meats and Poultry

Almost any tender cut of meat or poultry can be poached, and this technique offers an alternative to meats whose exteriors are browned and caramelized in the cooking process. Sweetbreads, eye of the round, small legs of lamb, duck and chicken breasts, and even beef tenderloins can be poached in stock, with or without vegetables, in a comparatively short time, and either served hot with a variety of sauces or served cold encased in a flavorful jelly or chaud-froid preparation. ( Chaud-froid, literally "hot-cold," is a seasoned white or brown sauce to which gelatin is added; it is then spooned over fish or meat and glazed with aspic.) is a classic variation on the traditional pot-au-feu, in which the beef tenderloin is tied with a string for easy removal from the poaching pan and served with vegetables and a reduction of the cooking stock. Formulas for finishing poached chicken breasts are as varied as the sauce repertoire for fish fillets, and again feature main course entrees as well as cold preparations.

A galantine is a dish made from the ground meat or forcemeat of poultry or meat that is stuffed into the skin of the chicken or duck of which it is made. Frequently the forcemeat is garnished with small cubes of ham, tongue, truffles, or pistachios. It is usually shaped into a cylindrical shape, wrapped in cheesecloth, tied with string, and poached in 176F (80C) liquid until an internal temperature of 160F (77C) is reached. When cool, the galantine is usually coated with aspic or a chaudfroid preparation.

Timbales, Terrines, and Quenelles

A large timbale (Arabic thabal, drum) is basically a preparation of forcemeat, meat, fish, or fruit baked with eggs and seasonings in a crust in a round mold with high sides. Small timbales are single servings of custards with forcemeat, shellfish, fish, pured vegetables and fruits made in glass or porcelain round molds instead of a crust and poached in a water bath of 176F (80C) in a warm oven. Nouvelle cuisine, especially, espoused a variety of flavorful pured vegetable timbales which captured the essence of the flavor of the main ingredient.

Whether a terrine is made with well-seasoned goose, duck, rabbit, venison, pork, or liver combined with forcemeat or delicate shellfish, fish, and vegetable mousse, the rectangular mold in which it is baked in the oven should be standing in a water bath whose temperature does not rise above 176F (80C). It is the gentle poaching that distinguishes the terrine from the pt, which is baked in a crust in a hot oven.

Quenelles, on the other hand, are meat or fish forcemeat dumplings that are bound with eggs, either piped or shaped into their distinctive oval shape with two spoons, and poached in lightly salted water. Small shaped quenelles are often used as elements in various garnishes, such as and Toulouse. Larger quenelles, usually containing truffles, are used to embellish sizeable whole fish and other entre presentations.

Poached Fruits

Although many nutritionists maintain that eating fruits raw provides the most vitamins, many out-of-season fruits or slightly under-ripe fruits can benefit from light cooking or poaching in a sugar syrup variously flavored with a cinnamon stick, cloves, orange, lemon zest, or vanilla. Cooking with the proper proportions of water and sugar firms the fruit, and when the fruit is lightly cooked and removed from the liquid, the fruit syrup can be reduced and thickened. At that point, fruit liquors, brandy, or rum can be added to the fruit sauce to reduce the sweetness and add more flavor. Fruits prepared this way make for simple but elegant desserts; however, poached fruits can also be glazed and served on meringues or cookies, or in custards or fruit tarts and compotes as in the classic Peach Melba and Pears Belle Hlne.

As a cooking technique that is almost ten thousand years old, poaching has always had a certain culinary cachet. Associated more often with feasting than with famine, the process of gently cooking delicate marrows, fish, shellfish, eggs, fruits, and certain kinds of poultry and meats in savory liquids has always lent finesse to various dishes, while, at the same time, exhibiting the skill of the cook.

BIBLIOGRAPHY

Child, Julia. The Way to Cook. New York: Knopf, 1989.

Corriher, Shirley O. Cookwise: The Hows and Whys of Successful Cooking. New York: William Morrow, 1997.

Culinary Institute of America. The New Professional Chef. Edited by Linda Glick Conway. New York: Van Nostrand Reinhold, 1991.

David, Elizabeth. French Country Cooking. New York: Knopf, 1980.

Ehlert, Friedrich W., et al. Pates and Terrines. New York: Hearst Books, 1984.

Montagn, Prosper. Larousse gastronomique: The Encyclopedia of Food, Wine, and Cookery. Edited by Charlotte Turgeon and Nina Froud. New York: Crown, 1961. First English edition.

Montagn, Prosper. Larousse gastronomique: The New American Edition of the World's Greatest Culinary Encyclopedia. Edited by Jennifer Harvey Lang. New York: Crown, 1988. Second English edition.

Montagn, Prosper. Larousse gastronomique : The World's Greatest Culinary Encyclopedia. Edited by Jennifer Harvey Lang. New York: Clarkson Potter, 2001. Third English edition.

Olney, Richard. Simple French Food. New York: Atheneum, 1975.

Ranhofer, Charles. The Epicurean. Reprint of 1893 Edition. New York: Dover, 1971.

Wheaton, Barbara Ketcham. Savoring the Past: The French Kitchen from 1300 to 1789. Philadelphia: University of Pennsylvania Press, 1983.
Joan Reardon

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POACHING. The "moist heat" technique of poaching was very much a part of the recorded recipes of the ancient world. In one of the earliest cookbooks, the Roman Apicius's De re Coquinaria, recipes for delicacies like Isicia Plena (Dumplings of Pheasant) show that stiff forcemeat dumplings were poached in water seasoned with garum.

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Air pollution refers to the release of pollutants into the air-pollutants that are detrimental to human health and the planet as a whole. According to the World Health Organization (WHO) , each year, indoor and outdoor air pollution is responsible for nearly seven million deaths around the globe. Ninety-nine percent of human beings currently breathe air that exceeds the WHO's guideline limits for pollutants, with those living in low- and middle-income countries suffering the most. In the United States, the Clean Air Act , established in 1970, authorizes the U.S. Environmental Protection Agency (EPA) to safeguard public health by regulating the emissions of these harmful air pollutants.

What Causes Air Pollution?

"Most air pollution comes from energy use and production," says , director of the Clean Air team at NRDC. Driving a car on gasoline, heating a home with oil, running a power plant on fracked gas : In each case, a fossil fuel is burned and harmful chemicals and gases are released into the air.

"We've made progress over the last 50 years in improving air quality in the United States, thanks to the Clean Air Act. But climate change will make it harder in the future to meet pollution standards, which are designed to protect health ," says Walke.

Air pollution is now the world's fourth-largest risk factor for early death. According to the 2020 State of Global Air report -which summarizes the latest scientific understanding of air pollution around the world-4.5 million deaths were linked to outdoor air pollution exposures in 2019, and another 2.2 million deaths were caused by indoor air pollution. The world's most populous countries, China and India, continue to bear the highest burdens of disease.

The effects of air pollution on the human body vary, depending on the type of pollutant, the length and level of exposure, and other factors, including a person's individual health risks and the cumulative impacts of multiple pollutants or stressors.

Smog and soot

These are the two most prevalent types of air pollution. Smog (sometimes referred to as ground-level ozone) occurs when emissions from combusting fossil fuels react with sunlight. Soot-a type of particulate matter -is made up of tiny particles of chemicals, soil, smoke, dust, or allergens that are carried in the air. The sources of smog and soot are similar. "Both come from cars and trucks, factories, power plants, incinerators, engines, generally anything that combusts fossil fuels such as coal, gasoline, or natural gas," Walke says.

Smog can irritate the eyes and throat and also damage the lungs, especially those of children, senior citizens, and people who work or exercise outdoors. It's even worse for people who have asthma or allergies; these extra pollutants can intensify their symptoms and trigger asthma attacks. The tiniest airborne particles in soot are especially dangerous because they can penetrate the lungs and bloodstream and worsen bronchitis, lead to heart attacks, and even hasten death. In 2020, a report from Harvard's T.H. Chan School of Public Health showed that COVID-19 mortality rates were higher in areas with more particulate matter pollution than in areas with even slightly less, showing a correlation between the virus's deadliness and long-term exposure to air pollution.

Hazardous air pollutants

Another category of toxic compounds, polycyclic aromatic hydrocarbons (PAHs), are by-products of traffic exhaust and wildfire smoke. In large amounts, they have been linked to eye and lung irritation, blood and liver issues, and even cancer. In one study , the children of mothers exposed to PAHs during pregnancy showed slower brain-processing speeds and more pronounced symptoms of ADHD.

Greenhouse gases

While these climate pollutants don't have the direct or immediate impacts on the human body associated with other air pollutants, like smog or hazardous chemicals, they are still harmful to our health. By trapping the earth's heat in the atmosphere, greenhouse gases lead to warmer temperatures, which in turn lead to the hallmarks of climate change: rising sea levels, more extreme weather, heat-related deaths, and the increased transmission of infectious diseases. In 2021, carbon dioxide accounted for roughly 79 percent of the country's total greenhouse gas emissions, and methane made up more than 11 percent. "Carbon dioxide comes from combusting fossil fuels, and methane comes from natural and industrial sources, including large amounts that are released during oil and gas drilling," Walke says. "We emit far larger amounts of carbon dioxide, but methane is significantly more potent, so it's also very destructive."

Pollen and mold

Mold and allergens from trees, weeds, and grass are also carried in the air, are exacerbated by climate change, and can be hazardous to health. Though they aren't regulated, they can be considered a form of air pollution. "When homes, schools, or businesses get water damage, mold can grow and produce allergenic airborne pollutants," says Kim Knowlton, professor of environmental health sciences at Columbia University and a former NRDC scientist. " Mold exposure can precipitate asthma attacks or an allergic response, and some molds can even produce toxins that would be dangerous for anyone to inhale."

Pollen allergies are worsening because of climate change . "Lab and field studies are showing that pollen-producing plants-especially ragweed-grow larger and produce more pollen when you increase the amount of carbon dioxide that they grow in," Knowlton says. "Climate change also extends the pollen production season, and some studies are beginning to suggest that ragweed pollen itself might be becoming a more potent allergen." If so, more people will suffer runny noses, fevers, itchy eyes, and other symptoms. "And for people with allergies and asthma, pollen peaks can precipitate asthma attacks, which are far more serious and can be life-threatening."

Air Pollution in the United States

More than one in three U.S. residents-120 million people-live in counties with unhealthy levels of air pollution, according to the by the American Lung Association (ALA). Since the annual report was first published, in 2000, its findings have shown how the Clean Air Act has been able to reduce harmful emissions from transportation, power plants, and manufacturing.

Recent findings, however, reflect how climate change-fueled wildfires and extreme heat are adding to the challenges of protecting public health. The latest report-which focuses on ozone, year-round particle pollution, and short-term particle pollution-also finds that people of color are 61 percent more likely than white people to live in a county with a failing grade in at least one of those categories, and three times more likely to live in a county that fails in all three.

In rankings for each of the three pollution categories covered by the ALA report, California cities occupy the top three slots (i.e., were highest in pollution), despite progress that the Golden State has made in reducing air pollution emissions in the past half century. At the other end of the spectrum, these cities consistently rank among the country's best for air quality: Burlington, Vermont; Honolulu; and Wilmington, North Carolina.

Air Pollution and Environmental Justice

No one wants to live next door to an incinerator, oil refinery, port, toxic waste dump, or other polluting site. Yet millions of people around the world do, and this puts them at a much higher risk for respiratory disease, cardiovascular disease, neurological damage, cancer, and death. In the United States, people of color are 1.5 times more likely than whites to live in areas with poor air quality, according to the ALA.

Historically, racist zoning policies and discriminatory lending practices known as have combined to keep polluting industries and car-choked highways away from white neighborhoods and have turned communities of color-especially low-income and working-class communities of color-into sacrifice zones, where residents are forced to breathe dirty air and suffer the many health problems associated with it. In addition to the increased health risks that come from living in such places, the polluted air can economically harm residents in the form of missed workdays and higher medical costs.

Environmental racism isn't limited to cities and industrial areas. Outdoor laborers, including the estimated three million migrant and seasonal farmworkers in the United States, are among the most vulnerable to air pollution-and they're also among the least equipped, politically, to pressure employers and lawmakers to affirm their right to breathe clean air.

Recently, cumulative impact mapping , which uses data on environmental conditions and demographics, has been able to show how some communities are overburdened with layers of issues, like high levels of poverty, unemployment, and pollution. Tools like the Environmental Justice Screening Method and the EPA's provide evidence of what many environmental justice communities have been explaining for decades: that we need land use and public health reforms to ensure that vulnerable areas are not overburdened and that the people who need resources the most are receiving them.

Controlling Air Pollution

In the United States, the Clean Air Act has been a crucial tool for reducing air pollution since its passage in 1970, although fossil fuel interests aided by industry-friendly lawmakers have frequently attempted to its many protections. Ensuring that this bedrock environmental law remains intact and properly enforced will always be key to maintaining and improving our air quality.

But the best, most effective way to control air pollution is to speed up our transition to cleaner fuels and industrial processes. By switching over to renewable energy sources (such as wind and solar power), maximizing fuel efficiency in our vehicles, and replacing more and more of our gasoline-powered cars and trucks with electric versions, we'll be limiting air pollution at its source while also curbing the global warming that heightens so many of its worst health impacts.

And what about the economic costs of controlling air pollution? According to a report on the Clean Air Act commissioned by NRDC, the annual benefits of cleaner air are up to 32 times greater than the cost of clean air regulations. Those benefits include up to 370,000 avoided premature deaths, 189,000 fewer hospital admissions for cardiac and respiratory illnesses, and net economic benefits of up to $3.8 trillion for the U.S. economy every year.

How to Help Reduce Air Pollution

"The less gasoline we burn, the better we're doing to reduce air pollution and the harmful effects of climate change," Walke explains. "Make good choices about transportation. When you can, ride a bike, walk, or take public transportation. For driving, choose a car that gets better miles per gallon of gas or buy an electric car ." You can also investigate your power provider options-you may be able to request that your electricity be supplied by wind or solar. Buying your food locally cuts down on the fossil fuels burned in trucking or flying food in from across the world. And most important: "Support leaders who push for clean air and water and responsible steps on climate change," Walke says.

How to Protect Your Health

"When you see in the news or hear on the weather report that pollution levels are high, it may be useful to limit the time when children go outside or you go for a jog," Walke says. Generally, ozone levels tend to be lower in the morning.

If you exercise outside, stay as far as you can from heavily trafficked roads. Then shower and wash your clothes to remove fine particles.

The air may look clear, but that doesn't mean it's pollution free. Utilize tools like the EPA's air pollution monitor, , to get the latest conditions. If the air quality is bad, stay inside with the windows closed.

If you live or work in an area that's prone to wildfires, stay away from the harmful smoke as much as you're able. Consider keeping a small stock of masks to wear when conditions are poor. The most ideal masks for smoke particles will be labelled "NIOSH" (which stands for National Institute for Occupational Safety and Health) and have either "N95" or "P100" printed on it.

If you're using an air conditioner while outdoor pollution conditions are bad, use the recirculating setting to limit the amount of polluted air that gets inside.

This story was originally published on November 1, 2016, and has been updated with new information and links.

This NRDC.org story is available for online republication by news media outlets or nonprofits under these conditions: The writer(s) must be credited with a byline; you must note prominently that the story was originally published by NRDC.org and link to the original; the story cannot be edited (beyond simple things such as grammar); you can't resell the story in any form or grant republishing rights to other outlets; you can't republish our material wholesale or automatically-you need to select stories individually; you can't republish the photos or graphics on our site without specific permission; you should to let us know when you've used one of our stories.

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Air Pollution: Everything You Need to Know

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The effects of air pollution wreck havoc on human health and our planet as a whole. Learn about what causes air pollution and how to help reduce the effects.

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Are you afraid of water pollution?

Have you heard a lot of very bad news lately about water pollution getting worse around the world?

Do you find yourself thinking often of people in your country and others who suffer from water pollution problems every day?

Would you like to learn how to save water from pollution?

If you think about this problem often, you might be wondering how to overcome water pollution problems. You might be concerned with cleaning up water pollution in your own home or neighborhood, and you might wish you could find a way to help out around the world and improve the quality of water for your fellow human beings.

So how can water pollution be reduced, improved, or stopped altogether? In this article, you'll find out answers to all these questions and more. You'll learn about the general idea of water pollution and where it comes from, and you'll be taken through six how-to steps that can help you clean up the water in your neighborhood. You'll even find out what can be done on a larger scale to improve water quality everywhere.

If you've been waiting for a good time to start learning about water pollution, you're in the right place. Below, you can find out how to solve the problem of water pollution no matter where you live. You'll learn how water pollution can be reduced and methods for better water health you can implement right away. In no time, you'll be so well-versed in good water practices you'll be ready to educate all your friends and family about them too.

Read on to learn more.

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What is Water Pollution?

You probably already know that the term "water pollution" refers to water that's dirty or full of things that shouldn't be there. However, there's a lot more to it than that, and fully understanding what water pollution is can make a big difference in learning more about it.

To begin with, water pollution does involve a given substance finding its way into water that isn't ordinarily a part of that water. However, when this happens, these substances aren't always pollutants. If the substances present in water aren't dangerous or toxic to human beings, then they aren't often labeled as pollutants. They are simply called contaminants in this situation.

Water pollution can cause a lot of problems other than just detriments to human health. When water is seriously polluted in a certain area, the soil, plants, animals, fish, and even insects suffer. Fish that live in a polluted water source die off quickly, which in turn causes widespread death in animals that eat those fish for survival. Of course, this can also affect humans who rely on those fish as well.

How Water Pollution Occurs

Now that you know what water pollution is and how to recognize it, you can find out more about what causes it in the first place. Understanding the causes of water pollution can help you better recognize them when you see them in your city, county, or neighborhood, and you'll be better able to take a stand against them too. So how does water pollution occur? Below are four of the most common ways.

1. Runoff

Runoff is a huge contributor to water pollution around the world. Anywhere toxic substances are present, runoff has the potential to cause problems. For example, if a construction site uses toxic chemicals or heavy metals and doesn't take proper precautions, rain that falls on that site will wash these substances away from the area and into the soil or surface water nearby.

2. Groundwater Pollution

While runoff is one cause of groundwater pollution, there are many others. When groundwater is polluted, that pollution is carried through the water table below the Earth's surface and eventually makes its way to surface water sources.

3. Surface Water Pollution

This is the type of water pollution people are most familiar with. This type of pollution is caused by objects that are left on the banks of rivers and lakes, wastewater that's dumped into rivers from factories and power plants, and a host of other types of contamination that get out of hand fast.

4. Marine Pollution

Although this article focuses mostly on problems with freshwater pollution, remember that marine water isn't safe from pollution either. When oil spills take place in the ocean, it may take years for those to be completely cleaned up. Sometimes, they are never cleaned, and they continue to cause widespread damage forever.

What are Some of the Common Sources of Water Pollution?

In this section, you'll find out some of the most common sources of water pollution. There are three different categories of water pollution, and each source falls into one of them.

The How-Tos of Water Pollution

Below, you'll find plenty of how-to tips to help you make the most of the water in your neighborhood and beyond. Remember that, while not all of these tips may apply to every area-and some may not apply to the place where you live-many of them are nearly universal in their practicality. Pick your favorite tips to put into practice right away, and choose a few to work toward in the future too!

Avoiding Water Pollution

1. If you want to learn how to protect water from pollution and improve the of water around your home, don't flush or wash garbage down the toilet or sink. Washing or flushing garbage is a sure way to cause a blockage or leak in your water line that will eventually seep into the groundwater around your home. Garbage washed down drains can lead to bacterial buildup and may spread illness.

2. ​ Add trenches around hard surfaces in your yard to improve runoff and keep it from traveling too far. Runoff carries sediment, dirt, and chemicals from driveways and other paved surfaces and allows it to enter the groundwater surrounding your home every time it rains. However, if you have a lot of trenches or plant lots of plants around your yard, these can help catch this runoff and keep it from getting too contaminated before it finds its way through the soil.

4 . ​Don't wash or work on your car at home.Doing so can cause oil spills in your own yard and may lead to a lot of chemicals used for cleaning and repairs to build up in the groundwater in your yard. In residential neighborhoods where many people work on and wash their cars in their yards or driveways, groundwater is much more heavily polluted than in places where they don't do this.

5. ​ harsh materials like batteries and paint. These types of products are some of the top contributors to water pollution runoff from landfills. They shouldn't be thrown in landfills at all but should be recycled at dedicated facilities. Unfortunately, most people don't know this or simply don't do it, and these products are left to leak and ooze into groundwater surrounding landfills all over the country.

6. ​Keep a fat under the sink instead of pouring cooking oils down the drain. When you dispose of oils down the drain, you encourage bacteria to build up in your water supply. Fill up the fat jar and simply throw it out with your solid wastes when you're finished with it.

7. ​Make the switch to water-saving t oil ets in your home.Many old toilets use way too much water, and you can help conserve clean drinking water for the whole neighborhood by using low-flush ones instead.

9. ​Don't run the dish washe r or washing machine until you have a full load. This can help conserve water and may even make your appliances run better, too.

10. Pitch in and help bushes and other plants along the banks of fresh water sources in your area. This can help reduce erosion and improve the health of the water. The less the soil erodes, the fewer chances there are for water to be polluted from sediments.

11. Don't forget: recycle! You probably already know recycling is good for the environment, but did you know it can help improve water too? When you recycle, you keep plastics and other chemical materials out of landfills. This cuts back on chemical pollution in groundwater surrounding those landfills.

12. So how can we avoid water pollution altogether? One tip to always keep in mind is to avoid water from a natural source without filtration.If you're hiking or camping in the woods, for example, you should always bring along a personal water filter to clean up your water before you drink it. At the very least, try to boil it first.

14. If you have a boil water advisory in your neighborhood, listen to it. Once again, these are usually in place for a good reason, and boiling your water may keep you from getting sick from bacteria or chemicals that might be present in the water.

15. T est the water in your home often.Nothing makes it easier to avoid water pollution at home than testing your water on a regular basis. Test your water at least once a year, or up to twice a year. You can send water samples off to labs across the country for detailed quality testing.

16. Don't use hot water unless you absolutely have to.Hot water is more likely to contain lead than cold water is, so avoid using it for cooking and washing clothes. Wash your hair in cold water, and don't use very hot water for washing your skin either.

18. If you have a swimming pool at home, take care with your treatment of the water. While it's important to treat your pool water to keep it free from bacteria and its own pollutants, be careful with harsh chemicals like chlorine. Store them properly and never dispose of them by dumping them in the yard.

19. If you'll be kayaking or otherwise interacting with water in natural places, such as in the mountains, look for information about possible water pollutants in the areas where you'll be traveling.The National Parks Service usually offers plenty of up-to-date information about water pollution in their parks. State parks may not always have this information listed online, but should be able to help if you give them a call.

20. I f you'll be visiting a water park or a theme park with a lot of water-based rides, do a little research ahead of time there as well.Some water parks have been known to have parasites and bacteria in their water. If this has been a recurring problem at the park you're considering visiting, you might want to make other plans.

Detecting Water Pollution

1. Start by looking for signs. Many of the visual signs of water pollution have to do with the color of the water. If it turns red or yellow, for example, it may be polluted with high numbers of heavy metals like copper or it may even contain iodine in some rare instances.

2. If everything looks okay, check the smell of the water. Water that has a strange smell may be polluted. If it smells like decaying material or has a strange mushroom sort of smell, there might be a lot of bacteria in your water supply. If you smell gas in your water, there may well be gas polluting it, and you need to get in touch with your water company right away.

3. Taste the water if all else fails. If the water doesn't taste right, there may be a pollutant present. Water that tastes old or musty may be polluted with bacteria, and water that tastes metallic may be polluted with high numbers of heavy metals.

5. Find out if water pollution issues are going on in areas surrounding yours. Sometimes the best way to detect water pollution in your area is to keep your eyes and ears open for problems in the neighborhood. If you notice your neighbors complaining of dirty or colored water, or if you hear about spills or dumping that might be taking place in the area, don't be afraid to have your water tested.

​6. If you're afraid you've been in contact with polluted water, there are a few you can be on the lookout for to help you detect any potential problems. For example, if you have a badly upset stomach, you might have ingested contaminated or polluted water. Learn more about water borne disease symptoms HERE.

7. Skin may also be a sign of contact with polluted water. If you wash or go swimming in water polluted with certain types of chemicals or even organic substances, they might cause your skin to have a reaction.

9. Water that is polluted with high levels can cause blue baby syndrome. This causes baby to turn blue and may be very fatal if not treated properly. This can be a very grim sign of exposure to polluted drinking water.

10. Certain types of pollutants might also cause respiratory problems. Especially if you've visited a developing country or have otherwise been drinking untreated water and soon develop trouble breathing, seek medical attention, as you may be suffering from an illness brought on by the water.

Decreasing and Fixing Water Pollution

1. So how can we reduce water pollution instead of just avoiding it? Start by staying away from harsh cleaning and those that contain antibacterial pesticides. When these are washed down your drains, they eventually end up at water treatment facilities or leaking through pipes into groundwater.

2 . ​Always turn the water when you aren't using it. A lack of water often leads to many types of pollution, so turn off the water to conserve it whenever possible. For example, after wetting your toothbrush, turn off the water until you're ready to rinse and spit. This can save a lot of water over time!

3. ​Don't flush medication or wash it down the drain, and don't run it through the garbage disposal. This can cause the same problem that washing garbage down the drain can: seriously polluted groundwater in your own yard and surface water in your area. Many cities offer specified locations where medication (and even sometimes illegal drugs) can be disposed of correctly with no questions asked.

5. For yet another great idea on how to reduce water pollution, just get out there and start talking to others! The more you spread the word about water pollution, the better off your neighborhood will be. Your friends and family will be more inclined to remember your words and cut back on using harsh products in their homes, and they'll remember to turn off the water when they aren't using it too.

6. If you're wondering how to fix water pollution, you can start by finding a local community cleanup project in your area. Most neighborhoods have cleanup projects, but if yours doesn't, it's easy to organize them on your own. Get in touch with nonprofit organizations to find out more.

7. ​ Aeration basically means introducing air to water and allowing natural processes to occur. This is a proven very effective way to remove gas pollutants and vapors from the water. The most common type of aeration is performed by a waterfall aerator, which breaks up polluted water into small droplets that allow gasses to escape. The other type of aeration is diffusion, which means water is forced against more water flowing in the opposite direction.

​9. Home filtration is a good option for dealing with less devastating but still troubling water pollution problems. Set up a home water filter to reduce heavy metals, organic pollutants, and even some types of gas that might find their way into your water. These filtration systems can also keep bacteria and parasites from reaching your drinking water.

10. ​So how can we save water from pollution around the world? If you're not able to volunteer with clean water organizations that focus on other countries, consider donating money, supplies, or even your talents in areas like web design or advertising to some of these groups.

11. But how can we solve water pollution anyway? The first step is education. The more people know about water pollution and its causes and effects, the more likely they'll be to practice safer water habits. We can all work together to improve the quality of water around the world by educating others about pollution.

13. Working toward better, more efficient irrigation is an important next step around the world. Irrigation uses up a lot of fresh water every year, but if it can take place in a more efficient manner, this water may be more available for clean drinking water purposes instead.

14. Improving the infrastructure that helps move water from place to place may, in turn, make the quality of water better in the long run. In some places, water pipes are so heavily contaminated with lead and other heavy metals that they pollute water as it travels from treatment facilities to individual homes and businesses. In other places, sewage and septic pipes leak so badly they allow human waste to pollute groundwater and spread diseases and parasites.

15. Utilizing rainwater may be a good step to take toward better and more plentiful water around the world. Using rainwater to water plants and even for industrial purposes can allow freshwater sources to be more readily available for drinking.

16. Helping to provide clean drinking water to developing countries can improve health around the world. Polluted water is one of the leading causes of widespread diseases in developing countries.

18. Encouraging local farmers to use natural forms of pesticides and fertilizers instead of relying on chemicals can change things for the better very quickly. Pesticides are the leading cause of water pollution in the United States and in many other countries, too. By moving toward safer methods of pest control in agriculture, we can cut down on water pollution immensely across the country.

19. ​Enforcing stricter regulations about wastewater and dumping may help improve the quality of groundwater. While there are plenty of regulations in place already, they aren't very heavily enforced. With stricter enforcements in place, factories would be forced to clean up and improve their operations.

. Working toward cleaner sources of fuel may help clean up water sources in the long run. Although clean fuel sources may be a controversial subject, it's true that they would be safer for water overall. If oil and gasoline spill during transportation or storage, they can be next to impossible to completely clean up from the environment.

Conclusion

Have you learned a lot about water pollution? Now that you've worked through this article, you should have a much better understanding of what constitutes water pollution and the many ways in which it might present itself. You should be more informed about the types of water pollution you might encounter in your neighborhood as well as the types that affect people around the world.

Best of all, you've also been introduced to several how-to tips that can help you improve the quality of water wherever you are. You've found out how we can reduce water pollution by working together, how to cut back on the effects of pollution, and how to clean up water that's been seriously polluted already. You even know how to figure out if water is polluted in the first place and how to avoid exposure to water that might be polluted.

All in all, you should be more than ready to start fighting back against the problem of water pollution. Whichever way you choose to get involved, there's something you can do to help fix water quality. You can pitch in with efforts around the world by donating time, money, or supplies to nonprofit organizations that work to provide clean drinking water to developing countries. You can also clean up closer to home by joining in efforts to improve rivers and wetlands in your area. Barring that, you can even help by cutting back on the number of harsh chemicals you use around the house and making sure to recycle whenever possible.

The more you do to help improve water quality, the better off the environment will be. Get started today and you'll see yourself making a difference in no time!

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50 Ways How To Solve Water Pollution Problems (SAVE OUR WATER)

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Are you afraid of water pollution? Have you heard a lot of very bad news lately about water pollution getting worse around the world?Do you find yourself thinking often of people in your country and others who suffer from water pollution problems every day? Would you like to learn how to save water from pollution?

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The world's largest species of orangutans is rapidly disappearing.

Borneo has lost more than 100,000 orangutans in the last 16 years - that's more than the number of the critically endangered species remaining.

This species - the Bornean orangutan - is only found on the island, which is divided between Malaysia, Indonesia and Brunei. It has seen dramatic deforestation, as lush jungle is converted into palm oil and paper pulp plantations.

But deforestation doesn't full explain the great apes' rapid decline. Maria Voigt, a scientist at the German Centre for Integrative Biodiversity Research, says hunting is "at least a major driver if not the major driver." The team's research, carried out through the Max Planck Institute for Evolutionary Anthropology, was published today in Current Biology.

Voigt and her research team compiled years of field surveys about the Bornean orangutans' population. "And after these 16 years, basically there was enough data to pull it together and combine it with information on things that influence orangutan numbers," she says.

Combining this information, she says, allowed the researchers to estimate orangutan numbers and how they've changed over time.

They overlaid that information with historical data about land use "to see what has happened in the different areas where we see decline," Voigt adds, "and then to kind of pick up what could be the reason for that decline.

Deforestation on the island is stark. Borneo "has the largest deforestation rates in the world, with an average 350,000 ha cleared every year between 2001 and 2016," according to the Center for International Forestry Research. Click here for a map from the CIFOR where you can see how the landscape has changed.

Forest fires are also a recurring threat to orangutans, Voigt says. Their assessment that 100,000 orangutans have been lost is "much higher than people had anticipated in a short time," Voigt says.

And it's worth noting that even though the deforested areas have seen the highest rates of decline, forested areas or areas that are selectively logged have seen the highest absolute number of orangutans lost.

"That's because while the rates of decline were less precipitous in those areas, that's also where far more orangutans are found," the researchers said in a statement.

Voigt says that in some ways, orangutans are more resilient and flexible than anticipated:

"They can walk on the ground for certain distances. They can also feed on plants like acacia or palm that are not their natural food. So they might be able to survive in landscapes where you have coexistence between development, in terms of plantations, and forests, as long as there is enough forest for them to survive and they are not killed."

But only occasional killing of orangutans can "already be enough to wipe the population out in the long term." Part of the reason is that their reproductive cycle is very long, averaging a baby only 6-8 years, she says.

It's likely that more have been lost in the last 16 years than remain alive, the researchers say. They estimate that 70,000 to 100,000 animals are left. And of the 64 remaining populations of orangutans on the island, just 38 have more than 100 individuals, which is considered the minimum to be viable in the long term.

There are two other species of orangutans - both only found in Sumatra, in Indonesia, and both critically endangered. The IUCN Red List (published by the International Union for Conservation of Nature) estimates that the Tapanuli Orangutan has fewer than 800 individuals remaining, and the Sumatran Orangutan has fewer than 14,000.

The Bornean Orangutans' survival, Voigt says, is going to depend on protecting the habitat that's still there, and raising awareness about how even occasional killing of the animals could lead to their extinction.

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Borneo Has Lost 100,000 Orangutans Since 1999

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The world's largest species of orangutans is rapidly disappearing. Borneo has lost more than 100,000 orangutans in the last 16 years - that's more than the number of the critically endangered species remaining. This species - the Bornean orangutan - is only found on the island, which is divided between Malaysia, Indonesia and Brunei.

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An annual study released by the Brazilian government estimates that the rate of deforestation in the Amazon has increased by 29 percent over last year.

That's the second year in a row that deforestation in the Amazon quickened; last year, the pace rose by about 24 percent.

The estimated deforestation rate, released Tuesday by Brazil's National Institute for Space Research (INPE), is based on satellite imagery. The institute found that from August 2015 to July 2016, the Amazon rainforest was deforested at an estimated rate of 7,989 square kilometers (more than 3,000 square miles).

The year before, it was 6,207 square kilometers. Two years ago, it was barely over 5,000 square kilometers.

INPE acknowledged the increase but noted that "the current rate represents a decrease of 71%, when compared with 2004." That was the year the government implemented a policy designed to curb deforestation; from 2004-2007, the rate of deforestation dropped rapidly.

But the rate now detected is the highest for any year since 2008. NPR's Lulu Garcia-Navarro, who has reported on deforestation in the Amazon, called it a "huge jump" in the deforestation rate.

The Brazilian newspaper Estadão reports that many observers had been prepared to see an increase in deforestation, but not one this high. Here's more from the newspaper, translated from Portuguese by NPR's Martin Kaste:

"Environmentalists working in the region had already been sounding the alarm, and in recent months the federal government had already been working on the assumption that the loss of forest would increase above the average of the last years, which has been below 6,000 km^2. But this number came as a surprise. ...

"The policy director of Greenpeace, Marcio Astrini, says among the causes of the increased deforestation were actions taken by the federal government between 2012 and 2015, such as the waiving of fines for illegal deforestation, the abandonment of protected areas - that is, 'conservation units' and indigenous lands - and the announcement, which he calls 'shameful,' that the government doesn't plan to completely stop illegal deforestation until the year 2030."

Estadão also notes that the rise in deforestation is raising concerns about Brazil's ability to meet its commitments as part of the international Paris Agreement on combating climate change.

Deforestation is a major contributor to climate change, and Brazil's success in reducing deforestation from 2004 to 2014 was seen as a model for other developing countries, Estadão writes.

Also on Tuesday, Reuters reported that a lack of funding has hampered the organization that's tasked with stopping illegal logging efforts.

The Brazilian Institute for the Environment and Renewable Natural Resources, or Ibama, has struggled with budget cuts as Brazil grapples with a recession, Reuters writes:

"Hampered by poor radios with a maximum range of just 2 km (1.3 miles) and pick-up trucks easily recognised by those who cut down the forest, the exhausted Ibama agents were too often chasing shadows.

" 'The loggers are better equipped than we are,' said Uiratan Barroso, Ibama's head of law enforcement in the state capital, Santarem. 'Until we have the money to rent unmarked cars and buy proper radios we won't be able to work.' ...

"A 30 percent cut in Ibama's budget has meant fewer operations this year. Helicopters and jeeps have been idle due to a lack of fuel.

" 'We haven't even had enough money to pay for aptitude tests to allow our agents to carry guns,' said Barroso, adding the tests only cost 200 reais ($60)."

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Deforestation Of The Amazon Up 29 Percent From Last Year, Study Finds

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An annual study released by the Brazilian government estimates that the rate of deforestation in the Amazon has increased by 29 percent over last year. That's the second year in a row that deforestation in the Amazon quickened; last year, the pace rose by about 24 percent.

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this is a good resource

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5 reasons wildlife matters

The huge variety of life on Earth contributes to our lives and well-being in more ways than we think. Discover why protecting wildlife matters to all of us.
Discover more
© naturepl.com / Mark Carwardine / WWF

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WWF - Building a future in which humans live in harmony with nature.

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5 reasons wildlife matters The huge variety of life on Earth contributes to our lives and well-being in more ways than we think. Discover why protecting wildlife matters to all of us. Discover more © naturepl.com / Mark Carwardine / WWF

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On National Doughnut Day, it's hard to imagine how our love of doughnuts might be contributing to deforestation halfway around the globe.

But here's the connection: You know that oily smudge left on your fingers after you polish off a doughnut? That's not just sugar. It's also palm oil.

The major doughnut retailers - from Dunkin' Donuts to Tim Hortons and Krispy Kreme - fry their sweet treats in palm oil, or in blends of oil that include palm oil.

And a new report, " Deforestation Doughnuts," by a rain forest protection coalition called Forest Heroes, concludes that leading doughnut companies are sourcing some of their palm oil from suppliers who are clear-cutting rain forests and destroying wildlife habitat and carbon-rich peatlands.

"The doughnut industrial complex is lagging behind," campaign director Glenn Hurowitz tells us.

He points to many big companies such as Kellogg, Mars and Hershey, which have meanwhile "taken steps to eliminate deforestation from their supply chains."

As we've reported, Kellogg made a splash earlier this year when it leaned on its palm oil supplier, Wilmar, to move forward with a No Deforestation, No Exploitation palm oil production policy.

We reached out to three leading doughnut retailers - Dunkin' Donuts, Krispy Kreme and Tim Hortons - who were named in the Forest Heroes report. And all of them told us that they are moving toward deforestation-free sourcing of palm oil.

"We are actively working on this issue," Olga Petrycki of Tim Hortons writes in an email. "And, ultimately, our goal is to purchase 100 percent of palm oil from verified sustainable sources."

Dunkin' Donuts, as we've reported, has already pledged to use 100 percent sustainable palm oil. In an email, Lindsay Harrington of Dunkin' Donuts says, "We are in the process of drafting a formal palm oil policy" that will be available by the end of 2014.

Krispy Kreme weighed in as well.

"We recognize the growing social and environmental concerns over palm oil production," Lafeea Watson of Krispy Kreme tells us, also by email. And she says the company has a "commitment to only source [palm oil] products for our U.S. locations from suppliers who are certified members of the Roundtable on Sustainable Palm Oil, and those who can guarantee compliance with all the sustainable palm oil production methods as defined in the guidelines."

The RSPO was created to promote sustainable palm oil, and it describes itself as having the world's toughest standards for producing palm oil. (Its principles and criteria for sustainable palm oil production are listed here.)

But recently, the RSPO has been criticized for having weak standards. And there are now efforts underway by nonprofit groups, including the World Wildlife Fund and Rainforest Action Network, and a few palm oil producing companies, to raise the bar on sustainability and push for more innovation. They call themselves the Palm Oil Innovation Group.

In its launch statement, that group says the current RSPO standards do "not go far enough to adequately address the most critical issues facing the industry today."

Among those issues, according to the Palm Oil Innovation Group, is the practice of clearing peatlands for new palm plantations. According to Greenpeace, one of the POIG members, clearing forests and draining and burning peatlands to grow palm oil release more greenhouse gas emissions than burning fossil fuels. POIG also mandates in its charter that all plantations already on peatlands maintain them to prevent additional emissions.

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Doughnut Day Downer: Palm Oil In Pastries Drives Deforestation

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On National Doughnut Day, it's hard to imagine how our love of doughnuts might be contributing to deforestation halfway around the globe. But here's the connection: You know that oily smudge left on your fingers after you polish off a doughnut? That's not just sugar. It's also palm oil.

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Is Paige and her love of straws to blame for water pollution?

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Is Paige and her love of straws to blame for water pollution?

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Slurping up smoothies, sodas and slushies through disposable plastic straws could one day become a thing of the past.

The call to toss plastic straws out of our food system is growing louder and louder. On Thursday Bon Appétit, a large food service company, announced it is banning plastic straws in all 1,000 of its cafes in 33 states, including locations like AT&T Park, home of the San Francisco Giants. The company says it plans to complete its transition to paper straws by September 2019.

It's the latest salvo in a growing war against straws.

The movement to oust plastic straws has spread across the U.S., from Miami Beach, where straws are now banned, to Malibu, where the prohibition also extends to single-use plastic utensils and stirrers.

The anti-straw movement comes amid growing recognition of the environmental toll of all the single-use plastics that people throw out. One compelling example of this: a video of a sea turtle with a plastic straw stuck up its nose, which was released a few years ago.

In 2014 alone, Americans tossed out more than 33 million tons of plastic, the vast majority of which was not recycled, according to the Environmental Protection Agency. One 2014 study estimated there are 270,000 metric tons - and more than 5 trillion particles - of plastic in the world's oceans. Straws and stirrers make up more than 7 percent of plastic products found in the environment, according to Better Alternatives Now, or BAN 2.0, an analysis done by several pollution research groups.

New York City Councilman Rafael L. Espinal Jr., a Democrat from Brooklyn, introduced a bill last week that would prevent restaurants in all five of the city's boroughs from providing plastic straws to customers.

"I've become increasingly aware of the impact that single-use plastic has on our oceans and environment," Espinal tells NPR. "Over the past few years, I started looking at single-use plastics that we can begin to eliminate without having severe impact on New Yorkers' daily lives. Plastic straws happen to be one of those [products]."

The bill would require that all establishments that serve food or drinks - from Yankee Stadium to street food vendors - phase out plastic straws by 2020. Espinal says he hopes to get the bill passed by the end of this summer, adding that Mayor Bill de Blasio is already on board to support the ban.

Companies including Alaska Airlines, as well as educational institutions such as University of Portland and Knox College, have also moved to ban plastic straws.

In the United Kingdom, several McDonald's locations have begun testing paper straws and putting plastic straws behind the counter. However, last week McDonald's voted down a shareholder proposal to study the issue at the chain's 37,000 locations globally. The fast-food giant's distinctive striped straws are the second-most-common brand found in the environment, according to the BAN 2.0 report. The most common: the bright green Starbucks straw.

Marcus Eriksen is the co-founder of the 5 Gyres Institute, a nonprofit that focuses on reducing plastics pollution, and a contributor to the BAN 2.0 paper and the 2014 study on ocean plastic pollution. He says straws are part of a larger movement to reduce the use of plastics in our daily lives.

"Straws are just the next of many," Eriksen says. "Microbeads, plastic bags, Styrofoam - they're all on the way out."

Some companies are exploring alternatives to plastic straws made of paper or wood. Other businesses have gotten creative, like Paradise Cove restaurant in Malibu, Calif., which now uses compostable, edible pasta in place of plastic straws.

There are also reusable straws made of silicone, glass and metal on the market. And some businesses have instituted a policy that customers must explicitly request a straw - plastic or otherwise - to get one. That's the law in Santa Cruz, Calif., which has banned not only plastic straws but also plastic cutlery and hot beverage lids. Nowadays, the city's food vendors can provide straws, lids, cutlery and condiment packages only if a customer requests them - even if these products are made from compostable materials.

Espinal likewise hopes to push his city to eliminate other plastics beyond straws. Another bill he introduced last week would prohibit vendors in parks and beaches from selling beverages in plastic bottles.

Espinal says he has gotten largely positive feedback for his call to decrease plastic waste. Hundreds of bars and restaurants in New York have already moved to phase out plastic straws of their own accord.

"There's a lot of support and this greater consciousness that this is the right thing to do," he says.

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Last Straw For Plastic Straws? Cities, Restaurants Move To Toss These Sippers

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Slurping up smoothies, sodas and slushies through disposable plastic straws could one day become a thing of the past. The call to toss plastic straws out of our food system is growing louder and louder.

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Below are a few key effects of air pollution. The last page on
What are the effects of air pollution?

FactSheet has some specific air pollution incidents that are worth checking out.

Chemical reactions involving air pollutants can create acidic compounds which can cause harm to vegetation and buildings. Sometimes, when an air pollutant, such as sulfuric acid combines with the water droplets that make up clouds, the water droplets become acidic, forming acid rain. When acid rain falls over an area, it can kill trees and harm animals, fish, and other wildlife.

Acid rain destroys the leaves of plants.
When acid rain infiltrates into soils, it changes the chemistry of the soil making it unfit for many living things that depend on the soil as a habitat or for nutrition. Acid rain also changes the chemistry of the lakes and streams that the rainwater flows into, harming fish and other aquatic life.
Acidification:

Eutrophication:
Rain can carry and deposit the Nitrogen in some pollutants on rivers and soils. This will adversely affect the nutrients in the soil and water bodies. This can result in algae growth in lakes and water bodies, and make conditions for other living organisms harmful.

Ground-level ozone:
Chemical reactions involving air pollutants create a poisonous gas ozone (O3). Gas Ozone can affect people's health and can damage vegetation types and some animal life too.

Particulate matter:
Air pollutants can be in the form of particulate matter which can be very harmful to our health. The level of effect usually depends on the length of time of exposure, as well the kind and concentration of chemicals and particles exposed to. Short-term effects include irritation to the eyes, nose and throat, and upper respiratory infections such as bronchitis and pneumonia. Others include headaches, nausea, and allergic reactions. Short-term air pollution can aggravate the medical conditions of individuals with asthma and emphysema. Long-term health effects can include chronic respiratory disease, lung cancer, heart disease, and even damage to the brain, nerves, liver, or kidneys. Continual exposure to air pollution affects the lungs of growing children and may aggravate or complicate medical conditions in the elderly.

NOTES
Particulate matter can come in almost any shape or size, and can be solid particles or very very tiny liquid droplets.

Big particles can be between 2.5 and 10 micrometers (about 25 to 100 times thinner than a human hair).

Small particles are smaller than 2.5 micrometers (100 times thinner than a human hair).

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Effects of Air Pollution on humans, plants and animals

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Below are a few key effects of air pollution. The last page on What are the effects of air pollution? FactSheet has some specific air pollution incidents that are worth checking out. Chemical reactions involving air pollutants can create acidic compounds which can cause harm to vegetation and buildings.

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It is critical we protect THE natural world.

The ecosystems that balance our climate and make life on Earth possible are under extreme threat. Without sufficient action, we are destined to take millions of species to extinction.

There has never been a more critical issue in the history of human civilization than the immediate protection of the natural world.

Our vision is the protection of the natural world.
With big global environmental challenges, we need big solutions. Taking on some of the largest biodiversity conservation projects on the continent, the IAPF delivers ecological stability and long-term protection of large-scale wilderness landscapes by supporting and empowering local communities.

We:
Connect: through scalable, innovative landscape conservation

Protect: through sustainable community empowerment programs

Restore: through effective leadership, research, & partnerships

Protecting nature at scale is one of the greatest ways to mitigate climate change and future pandemics. Join us today by taking back the future through community-based nature conservation.

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Founded in 2009, International Anti-Poaching Foundation (IAPF) has transformed the traditional adversarial approach to conversation into an innovative, empowering, and gender-diverse model to protect wildlife and habitats. They connect, protect and restore conservation landscapes, working together with local communities, governments and NGOs, through their Akashinga conservation model, featuring all-female teams of wildlife rangers in Africa.

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Most poachers and African criminal syndicates receive only 5-10% of the retail value for the animal parts they poach. Even in destitute parts of Africa and Asia this is little reward for what can be a very risky task of spending days tracking dangerous wildlife in their natural habitat. Coordinated efforts to exterminate rhino and elephants in central Africa, as well as systematic poaching in Southeast Asia and China, have made it easier for criminal syndicates to organize a market for tiger and leopard skins, elephant ivory, and rhino horn. This has provided a channel for low-level poachers and high-level rebel militias to sell their animal parts to middlemen who then smuggle the cargo en mass to destinations around the globe where the items are sold for exorbitant prices.

In 2013 the street-price for rhino horn in Asia was $60,000-100,000 per kilogram. At roughly $1,700-2,840 per ounce, more than the price of gold, it was believed to be a better investment than real estate and an easy way to show off wealth. According to anti-poaching forces in South Africa a Mozambican poacher would earn R100,000 ($10,000) per hunt or over R200,000 per horn depending on the middleman.

In January of 2015 Ugandan officials seized a shipment of 137 ivory tusks weighing 700 kg and destined for Amsterdam. The ivory in this shipment had an estimated street value of $1.5 million or $2,142 per kilo or roughly $973 per pound. As a result of international pressure to end the illicit ivory trade, as well as other factors impacting legal domestic markets where elephant ivory is still sold, the average price of ivory in China has fallen to $730 per kilogram ($331 per pound).

India's diverse ecosystems suffer from the loss of its the native species of Bengal tiger, leopard, Indian rhinoceros, and Asian elephant. In 2009 a single tiger skin smuggled from India would sell for 650,000 rupees in China, approximately $134,000 or 91,920 yuan. However in recent years poaching and wildlife trafficking have received more attention and more poachers and traffickers are being sentenced to jail time for their crimes.

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Most poachers and African criminal syndicates receive only 5-10% of the retail value for the animal parts they poach. Even in destitute parts of Africa and Asia this is little reward for what can be a very risky task of spending days tracking dangerous wildlife in their natural habitat.

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On March 24, 1989, the oil tanker Exxon Valdez had just entered Alaska's Prince William Sound, after departing the Valdez Marine Terminal full of crude oil. At 12:04 am, the ship struck a reef, tearing open the hull and releasing 11 million gallons of oil into the environment. Initial responses by Exxon and the Alyeska Pipeline Company were insufficient to contain much of the spill, and a storm blew in soon after, spreading the oil widely. Eventually, more than 1,000 miles of coastline were fouled, and hundreds of thousands of animals perished. Exxon ended up paying billions in cleanup costs and fines, and remains tied up in court cases to this day. The captain, Joseph Hazelwood, was acquitted of being intoxicated while at the helm, but convicted on a misdemeanor charge of negligent discharge of oil, fined $50,000, and sentenced to 1,000 hours of community service. Though the oil has mostly disappeared from view, many Alaskan beaches remain polluted to this day, crude oil buried just inches below the surface.

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On March 24, 1989, the oil tanker Exxon Valdez had just entered Alaska's Prince William Sound, after departing the Valdez Marine Terminal full of crude oil. At 12:04 am, the ship struck a reef, tearing open the hull and releasing 11 million gallons of oil into the environment.

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Newsela | Pain remains from the Exxon Valdez oil spill 25 years later

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At the time, it was the nation's biggest oil spill. And whether Prince William Sound in Alaska has by now recovered remains a contentious issue.

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Forests cover 31% of the land area on our planet. They help people thrive and survive by, for example, purifying water and air and providing people with jobs; some 13.2 million people across the world have a job in the forest sector and another 41 million have a job that is related to the sector. Many animals also rely on forests. Eighty percent of the world's land-based species, such as elephants and rhinos, live in forests. Forests also play a critical role in mitigating climate change because they act as a carbon sink-soaking up carbon dioxide that would otherwise be free in the atmosphere and contribute to ongoing changes in climate patterns.

But forests around the world are under threat, jeopardizing these benefits. The threats manifest themselves in the form of deforestation and forest degradation. The main cause of deforestation is agriculture (poorly planned infrastructure is emerging as a big threat too) and the main cause of forest degradation is illegal logging. We're losing 18.7 million acres of forests annually, equivalent to 27 soccer fields every minute.

Deforestation is a particular concern in tropical rain forests because these forests are home to much of the world's biodiversity. For example, in the Amazon around 17% of the forest has been lost in the last 50 years, mostly due to forest conversion for cattle ranching. Deforestation in this region is particularly rampant near more populated areas, roads and rivers, but even remote areas have been encroached upon when valuable mahogany, gold, and oil are discovered.

WWF has been working to protect forests for more than 50 years. WWF works with governments, companies, communities and other stakeholders to promote certification for responsible forest management practices, combat illegal logging, reform trade policies, protect forested areas, and more.

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Deforestation and Forest Degradation | Threats | WWF

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Forests cover 31% of the land area on our planet. They help people thrive and survive by, for example, purifying water and air and providing people with jobs; some 13.2 million people across the world have a job in the forest sector and another 41 million have a job that is related to the sector.

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The problems caused by an excess of dissolved nutrients in freshwater systems

Introduction Types of freshwater pollution

Anions Detergents Gases Heat Metals Organic pollution Pathogens Acids & alkalis

Definitions

Aquatic plants (like any other plants) need two essential nutrients to grow: nitrogen (N) and phosphorus (P). In a healthy lake the nutrients occur in small amounts. But in large quantities, they can cause a major water pollution problem. Too many nutrients stimulate the rapid growth of plants and algae, clogging waterways and sometimes creating blooms of toxic blue-green algae. This process is called eutrophication. The result of this is that when the plants and algae die and decompose, they use up large amounts of oxygen (O ₂). So the amount of oxygen that is available for fish and other aquatic species will be reduced. In extreme cases it can lead to a completely oxygenl ess environment that can support nothing except a few species of anaerobic bacteria. It also can kill fish and other aquatic life and reduce the aesthetic and recreational value of the lake.
The nutrients include nitrates found in sewage and fertilizers, and phosphates found in detergents and fertilizers. Human inputs of nutrients from the atmosphere and from nearby urban and agricultural areas can accelerate the natural eutrophication of lakes, a process called cultural eutrophication.

Nutrients from urban sources may be derived from domestic sewage, industrial wastes and storm drainage. The contribution of nitrogen and phosphorus per person per day averages 10.8 g N and 2.2 g P, though there is a considerable range. In the 1940s detergents were developed containing sodium tripolyphosphate, which softens water by neutralizing calcium and keeps dirt in suspension once it has washed off clothes.
These are the principal sources of nutrient overload causing cultural eutrophication in lakes. The amount of each source varies according to the types and amounts of human activities occurring in each airshed and watershed.

Related pages:

Nutrients irrigation water

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sand filter filtration bag cartridge micron ss iron removal membrane fine coarse pre reuse stainles steel drum disc filter hydrotech ab reversed osmosis amazon housing house

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Eutrophication in aquatic freshwater systems

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The problems caused by an excess of dissolved nutrients in freshwater systems Introduction Types of freshwater pollution Anions Detergents Gases Heat Metals Organic pollution Pathogens Acids & alkalis Definitions Aquatic plants (like any other plants) need two essential nutrients to grow: nitrogen (N) and phosphorus (P).

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if like the hunters are poached all the prey will overpopulate and there won't be enough food, so they'll die, and then yeah

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This article is available in: English | Afrikaans | Sotho | Zulu
The substances that cause water pollution can be divided into two main groups - germs and chemicals. Germs are small organisms that cause diseases such as malaria, cholera and bilharzia, and chemicals are poisons, which are mainly produced by industries.

1. Possible Poisonous Chemicals in River Water

Natural chemicals are found everywhere in the environment. Unfortunately, many of the chemicals that are produced by industries are not found naturally in the environment or are only found in very small amounts. Different industrial processes produce different types of products and waste products. Unfortunately many industries release their waste products directly into rivers or let them leak into the groundwater. These chemicals are poisonous or toxic to plants, animals and people. Some examples are:

Insecticides

Insecticides are chemicals that are sprayed onto crops to kill the insects that eat crops. One of the more controversial insecticides is DDT. The use of DDT on crops was used to control the malaria mosquito in South Africa. At certain levels (10 mg per kg) DDT can cause human poisoning with the following symptoms: dizziness, vomiting and convulsions. At lower levels, DDT can affect the development of babies and has been associated with cancer. DDT has been banned in South Africa. Another group of controversial insecticides are the organo-phosphates. These insecticides have been used in the place of DDT since it was banned. Some specialists believe that these insecticides have caused even greater environmental damage than DDT and that they are even more toxic to humans and other mammals.

Insecticides are easily washed by the rain into streams and groundwater where they poison fish and domestic animals. Many insecticides are stored for a long time in the bodies of animals and can end up in the meat, fish, egg and milk that you eat. Fruits and vegetables that have been sprayed with insecticides also remain poisonous for many days afterwards and must be washed very well before eating.

Ask questions about the use of insecticides in your area. Keep a look out for fish or birds that have been poisoned. Dead fish and birds provide a good indicator of chemical pollution. If you suspect pollution by insecticides then contact your local council as soon as possible.

Heavy Metals

Heavy metals such as nickel, molybdenum, zinc, cadmium and lead are mined and processed by the mining and ore-smelting industries, many of which occur in Gauteng. These metals are easily washed into streams and groundwater. Copper and mercury are another two heavy metals, which are found in fungicides. Fungicides are also sprayed on crops and easily washed into rivers. These heavy metals are toxic to biological life including the people who may have to drink from the polluted rivers. Crops that have been irrigated with polluted water can also be dangerous. In a similar way to DDT, heavy metals can also build up in the body causing symptoms of poisoning.

In the past, toxic waste products were dumped into the rivers or into landfill sites close to where people lived causing health problems and even death. Today all South Africans have a constitutional right to a clean and safe environment. Make sure that you remain informed and observant so that you can prevent toxic chemicals from being used in your environment. If you suspect water pollution in your area then contact your local council.

Problem Products

We all know about the destruction that oil pollution causes along the marine coastline. However, a lot of oil pollution also occurs inland. Petrol and diesel is stored in underground tanks at petrol depots. When these tanks are not properly maintained, they can develop cracks allowing the petrol to leak out. Many people are also very negligent when changing the oil in their car engines. Many people just throw the oil onto the ground! This oil and petrol is washed by the rain into the groundwater. This ground water eventually surfaces at boreholes and wetlands. In the past, groundwater was considered clean since chemicals and germs were not present, but this is changing very quickly. Groundwater is becoming more and more polluted with a number of toxic substances including insecticides, petroleum products and heavy metals. South Africa is a dry country and as the human population grows, our groundwater is becoming very valuable. We must all work towards keeping this resource as clean as possible for the future when we really need it.

Chlorine and Detergents

Paper and pulp mills and textile factories are amongst the worst water polluters. Paper and pulp mills use up large amounts of water and produce a lot of polluted wastewater. The wastewater contains strong chemicals such as chlorine, which is used to make paper white and soft. Textile factories also release strong chemicals like caustic soda, acids, dyes and detergents into water. These strong poisons also cause bird and fish kills similar to insecticide poisoning. These chemicals are also directly poisonous to humans. Ask questions about what industries occur in your area and how they release their wastewater. Do not drink water that is downstream from a factory that releases wastewater into the river.

Remember that the detergents that you use at home are just as poisonous so use only biodegradable products. Read the label on the product that you are buying; this will tell you what the product is made of and if it is environmentally friendly.

2. Fertilisers and Sewage

Some chemicals like fertilisers are made of substances that do occur naturally in the environment, but only in small amounts. When too much fertiliser is washed from farmlands into a river then that water will also become polluted. Human sewage or cattle excrement that is untreated also causes water pollution in the same way as fertilisers do. Human sewage also contains germs that cause diseases such as hepatitis and cholera. Soaps and washing detergents contain both natural and man-made (artificial) chemicals. Artificial chemicals like bleach and chlorine were discussed earlier. The natural chemicals can cause a pollution problem similar to that caused by fertilisers.

Phosphates and nitrates are found in fertilisers, sewage and soaps. Phosphorus is an essential element for life, both as a nutrient for plant life and as a key element in the metabolic processes of all living things. The normal low phosphate (PO ₄) level in water inhibits the growth of plants but a small increase of phosphates can result in a rapid increase in plant growth such as blue-green algae and water hyacinth, especially in dams. The water plants become overcrowded and die. When they die the decomposing bacteria uses up more oxygen and affects other forms of life badly, eg. fish suffocate. This process is called eutrophication, and can be increased by human activities, eg. domestic effluent (especially soapy water), farm and lawn fertilisers, industrial effluent and the destruction of wetlands.

Nitrogen in the form of ammonia (NH ₃) and nitrates (NO ₃) form part of the plant nutrients that can lead to eutrophication. Nitrate enrichment through sewage contamination and fertiliser runoff is not as critical as it is with phosphates because aquatic ecosystems are not as sensitive to increases in nitrate levels. Nitrogen normally occurs in a form that plants cannot use (i.e. nitrogen gas), however, it may be used in the decomposition of dead water plants and by blue-green algae which can convert nitrogen in the air into ammonia and nitrates that plants can use. This subtle interdependence illustrates the complexity of the relationships within an aquatic ecosystem. The best way to stop this kind of pollution is to prevent human sewage, cattle excrement and fertilisers from washing into rivers.

Blue-Green Algae
Blue-green algae are microscopic inhabitants of rivers. They liberate oxygen into the water, take up mineral nutrients and produce substances which enter and support food chains in the aquatic environment. With a rise in river pollution there is an increase in nutrients. This causes a great increase in the growth of blue-green algae, which are called algal blooms. These blooms have an effect on the colour, taste and odour of rivers. Human contact with these algal blooms can cause illness, such as hayfever, skin rashes, eye irritations, vomiting, gastroenteritis, diarrhoea, fever and pains in muscles and joints.

3. Water Pollution and Disease

Most diseases in the world are related to water and sanitation. To break the cycle of disease, there must be improvements in the quality of water that people use. Most rural communities in South Africa do not have access to running water, toilets or latrines and they use watercourses for defecation and urination. In many cases, where they are present, latrines are situated upstream from where the community collects their water supply. Faecal pollution of water increases the risk of infection of various diseases to those using these courses as their life supporting water source. Groundwater, which is another water source, can become contaminated through unclean irrigation water. Water related diseases could be spread in other ways, which also affect urban communities, such as insect bites and poor hygiene.

Although there are many more, these are some of the most common water - related diseases in South Africa:

Bilharzia

This occurs, like most diseases, in a cycle with a parasite and different hosts. Bilharzia only occurs in areas where conditions are right for the parasite to be able to complete its life cycle. The adult parasite is a worm that lives in the bladder or intestine of humans (the main host). They mate inside the body and eggs are released in the urine or faeces of the host. If an infected person defaecates and urinates into the water, the eggs hatch into the swimming form of the parasite. It then burrows into the body of a snail (the intermediate host). The snails favour slow moving water with plenty of vegetation. Here the parasite changes form and exits out into the water again. This is the stage that infects humans. If a person has contact with contaminated water the parasite will penetrate their skin and move through the body causing illness. Some symptoms of Bilharzia: an itchy rash, headaches, abdominal pain, diarrhea, bladder infections, fever, enlarged liver and swollen veins. Within South Africa, Bilharzia is most common in the Northern Province, the Lowveld and KwaZulu-Natal.

Malaria

In South Africa Malaria is given very high priority. This disease, which also occurs as a cycle, is caused by a parasite that is transmitted by some species of female mosquitoes. The female mosquito requires a blood meal in order to obtain sufficient energy and nutrients to produce her eggs. When a mosquito bites a human, it injects saliva into the bloodstream to prevent the blood from clotting. If the mosquito is infected with the malarial parasite, the parasite will be released from the mosquito's saliva into the blood of the human. The parasite travels through the body and enters the red blood cells. The red blood cells eventually burst releasing the parasite into the blood stream where it is ready to be sucked up by the next mosquito. Mosquitoes breed in water, especially dams, ponds, water tanks, old car tyres, and other hollow objects that can hold water, like tins. The best way to protect yourself from Malaria is not to leave litter lying around, and to prevent getting bitten by wearing long sleeve clothing and by applying insect repellent to your skin, especially at night. Some symptoms of Malaria: fever, headache, diarrhoea, nausea, joint and muscular pains, shivering, sweating and fatigue. Malaria is distributed in the Northern Province, Mpumalanga, Northern KwaZulu-Natal and parts of the northern Cape.

Cholera

Cholera is a disease that is caused by bacteria (Vibrio cholerae) that is spread through water contaminated by faeces from an infected person. The bacteria produce a toxin that causes the small intestine to secrete large amounts of fluid, which leads to fluid loss, i.e. diarrhoea and vomiting. People who do not wash their hands after using the toilet can spread the disease. It can also be spread when human faeces are used as a fertiliser for vegetable crops. It is important to remember that even if a person does not show symptoms of the disease, they could still be infected and spread the disease. Cholera can be found in most places where there is poor sanitation. Some symptoms of Cholera: diarrhoea and vomiting. People who have the disease should drink plenty of clean water to prevent dehydration.

Important Things That You Can Do to Decrease the Risk of Disease

Do not defaecate or urinate near water sources;

Wash your hands with soap and water after going to the toilet;

Do not drink water that you think might be unclean - boil it if you are unsure;

Wash all fruit and vegetables well before eating them & do not cook with unclean water;

Do not leave empty containers or any litter lying around for disease transmitting insects to breed in;

If you have access to pit latrine facilities, ensure that they are away from sources that are used for drinking and bathing. The pit should not penetrate groundwater.

See also

Rural Water Purification
Water Pollution and Your Health
Water Situation in South Africa

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The substances that cause water pollution can be divided into two main groups - germs and chemicals. Germs are small organisms that cause diseases such as malaria, cholera and bilharzia, and chemicals are poisons, which are mainly produced by industries.

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8 Billion Opportunities: On November 15, 2022 humanity's population eclipsed 8 billion people. What Does This Mean?

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Deepwater Horizon oil spill, also called Gulf of Mexico oil spill, largest marine oil spill in history, caused by an April 20, 2010, explosion on the Deepwater Horizon oil rig-located in the Gulf of Mexico, approximately 41 miles (66 km) off the coast of Louisiana -and its subsequent sinking on April 22.

Deepwater Horizon oil spill: debris and oil U.S. Coast Guard

The explosion

The Deepwater Horizon rig, owned and operated by offshore-oil-drilling company Transocean and leased by oil company BP, was situated in the Macondo oil prospect in the Mississippi Canyon, a valley in the continental shelf. The oil well over which it was positioned was located on the seabed 4,993 feet (1,522 metres) below the surface and extended approximately 18,000 feet (5,486 metres) into the rock. On the night of April 20 a surge of natural gas blasted through a concrete core recently installed by contractor Halliburton in order to seal the well for later use. It later emerged through documents released by Wikileaks that a similar incident had occurred on a BP-owned rig in the Caspian Sea in September 2008. Both cores were likely too weak to withstand the pressure because they were composed of a concrete mixture that used nitrogen gas to accelerate curing.

Once released by the fracture of the core, the natural gas traveled up the Deepwater rig's riser to the platform, where it ignited, killing 11 workers and injuring 17. The rig capsized and sank on the morning of April 22, rupturing the riser, through which drilling mud had been injected in order to counteract the upward pressure of oil and natural gas. Without any opposing force, oil began to discharge into the gulf. The volume of oil escaping the damaged well-originally estimated by BP to be about 1,000 barrels per day-was thought by U.S. government officials to have peaked at more than 60,000 barrels per day.

Leaking oil

Although BP attempted to activate the rig's blowout preventer (BOP), a fail-safe mechanism designed to close the channel through which oil was drawn, the device malfunctioned. Forensic analysis of the BOP completed the following year determined that a set of massive blades known as blind shear rams-designed to slice through the pipe carrying oil-had malfunctioned because the pipe had bent under the pressure of the rising gas and oil. (A 2014 report by the U.S. Chemical Safety Board claimed that the blind shear rams had activated sooner than previously thought and may have actually punctured the pipe.)

Deepwater Horizon oil spill of 2010: path of the oil Encyclopædia Britannica, Inc.

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Efforts in May to place a containment dome over the largest leak in the broken riser were thwarted by the buoyant action of gas hydrates-gas molecules in an ice matrix-formed by the reaction of natural gas and cold water. When an attempt to employ a "top kill," whereby drilling mud was pumped into the well to stanch the flow of oil, also failed, BP in early June turned to an apparatus called the Lower Marine Riser Package (LMRP) cap. With the damaged riser shorn from the LMRP-the top segment of the BOP-the cap was lowered into place. Though fitted loosely over the BOP and allowing some oil to escape, the cap enabled BP to siphon approximately 15,000 barrels of oil per day to a tanker. The addition of an ancillary collection system comprising several devices, also tapped into the BOP, increased the collection rate to approximately 25,000 barrels of oil a day.

In early July the LMRP cap was removed for several days so that a more permanent seal could be installed; this capping stack was in place by July 12. Though the leak had slowed, it was estimated by a government-commissioned panel of scientists that 4,900,000 barrels of oil had already leaked into the gulf. Only about 800,000 barrels had been captured. On August 3 BP conducted a "static kill," a procedure in which drilling mud was pumped into the well through the BOP. Though similar to the failed top kill, mud could be injected at much lower pressures during the static kill because of the stabilizing influence of the capping stack. The defective BOP and the capping stack were removed in early September and replaced by a functioning BOP.

The success of these procedures cleared the way for a "bottom kill," considered to be the most likely means of permanently sealing the leak. This entailed pumping cement through a channel-known as a relief well-that paralleled and eventually intersected the original well. Construction of two such wells had begun in May. On September 17 the bottom kill maneuver was successfully executed through the first relief well. The second had been intended to serve as a backup and was not completed. Two days later, following a series of pressure tests, it was announced that the well was completely sealed.

Claims by several research groups that subsurface plumes of dispersed hydrocarbons had been detected in May were initially dismissed by BP and the National Oceanic and Atmospheric Administration (NOAA). However, it was verified in June that the plumes were in fact from the Deepwater spill. The effect of the microscopic oil droplets on the ecosystem was unknown, though their presence, along with that of a layer of oil several inches thick discovered on portions of the seafloor in September, cast doubt on earlier predictions about the speed with which the discharged oil would dissipate. Bacteria that had adapted to consuming naturally occurring gas and oil seeping from the seabed were thought to have consumed a portion of it.

Deepwater Horizon oil spill

date

April 20, 2010 - September 19, 2010

location

causes

An explosion that capsized the Deepwater Horizon oil rig

outcomes

Payment by oil company BP of $65 billion in compensation to people impacted by the spill

11 workers killed and 17 injured by the explosion on the Deepwater Horizon oil rig

About 1,300 miles (2,100 km) of the U.S. Gulf Coast covered in oil

Massive harm done to wildlife in and around the Gulf of Mexico, including the deaths of an estimated 800,000 birds and 65,000 turtles

Release of an estimated 134 million to 206 million gallons of oil into the Gulf of Mexico

context

key people

related topics

did you know?

As much as 20 percent of the oil spilled may have sunk to the bottom of the ocean, damaging deep-sea ecosystems.

In the process of reaching a settlement with BP, the largest natural-resource damage assessment ever was undertaken.

The 3.19 million barrels found by the courts to have leaked during the spill is equal to over 130 million gallons.

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Deepwater Horizon oil spill | Summary & Facts

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Deepwater Horizon oil spill, largest marine oil spill in history, caused by an April 20, 2010, explosion on the Deepwater Horizon oil rig-located in the Gulf of Mexico, approximately 41 miles (66 km) off the coast of Louisiana-and its subsequent sinking on April 22.

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Kids Environment Kids Health - National Institute of Environmental Health Sciences

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On April 20, 2010 there was an explosion on the Deepwater Horizon offshore drilling platform in the Gulf of Mexico. Two days after the explosion and fire, the oil drilling rig sank. A huge amount of crude oil leaked from the oil well. The leak was about 5,000 feet below the surface of the Gulf.

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Definition

Water pollution is defined as the presence in groundwater of toxic chemicals and biological agents that exceed what is naturally found in the water and may pose a threat to human health and/or the environment. Additionally, water pollution may consist of chemicals introduced into the water bodies as a result of various human activities. Any amount of those chemicals pollutes the water, regardless of the harm they may pose to human health and the environment.

Causes

Many of the chlorinated solvents commonly used in industry (such as PCE, TCE, 1,1,1-TCA) are examples of such chemicals polluting our waters exclusively due to human activities. Another example is MTBE (Methyl-tert-butyl-ether), a gasoline oxygenate that is currently banned in the U.S. Regardless of their provenance, the chemicals or biological agents causing water pollution are generically referred to as water pollutants.The chemical and biological agents represent the main causes of water pollution and are generically referred to as water pollutants.

Any kind of water can become polluted, regardless of its size or location. This includes lakes from remote areas or huge water bodies and is due to the air transportation of pollutant particles and their transfer into precipitation water. The groundwater and surface water consist of swimming pools, ponds, lakes, creeks, rivers, seas, and oceans that may all become polluted at some point. Due to the quick diffusion and dissipation of contamination and the faster natural degradation processes, the bigger the water body is, the shorter the time required for naturally cleansing the pollution and recovery.

Types of Water Pollution

There are various types of water pollution based on the various causes of water pollution. Various classifications can be made, based on various water pollution causes:

1. The type of the water pollutants - based on this classification criteria, water pollution can be:

I) Chemical - when various chemicals are the water pollution causes. The following chemicals are the most common water pollutants:

Crude oil and various petroleum products (including gasoline, diesel fuel, kerosene, motor and lubricating oils, jet fuel). These compounds are lighter than water and thus always sit on top of water forming sheens of "free product". However, part of these compounds dissolve in water and, even in small amounts may be harmful and at the same time may remain unnoticeable by the eye.

Fertilizers (including nitrates and phosphates) - while small amounts are useful to life, higher amounts of nitrates and phosphates in water are only beneficial to algae and harmful microorganisms and are poisonous to human and aquatic life. These contaminants cannot be seen themselves in water (as they do not form sheens or color the water), but their effects can. The typical effect of water pollution by fertilizers (usually through agricultural runoff) is the fast and abundant water growth.

Chlorinated solvents (including TCE, PCE, 1,1,1-TCA, carbon tetrachloride, Freons) which sink in water (are denser than water) and are quite persistent and toxic. These compounds thus, cannot be seen by the eye, in contrast with petroleum products that are easily seen as sheens on top of water surface.

Petroleum solvents (including benzene, toluene, xylenes, ethylbenzene)

Other organic solvents and chemicals (such as acetone, methyl ethyl ketone, alcohols such as ethanol, isopropanol; or oxygenate compounds such as MTBE)

Antibiotics and other pharmaceutical products;

Perchlorate - perchlorate salts are used in rocket fuels, as well as many other applications such as fireworks, explosives, road flares, inflation bags, etc. This contaminant is usually associated with military bases, construction sites (when explosives are used). However, natural formation in arid areas may account for perchlorate in water, too (e.g., in Chile, Texas or California where natural formation of perchlorate has been observed)

Trihalomethanes - these are usually byproducts of water chlorination and may pollute groundwater and surface water via leaking sewer lines and discharges. Examples of such compounds are: chloroform, bromoform, dichlorobromomethane;

Metals and their compounds - of higher health risk are the organo-metal compounds which may form when metals from water react with organic compounds from water. Common examples include Hg, As, and Cr poisoning of water. Thus, if water is polluted with both metals and organic compounds the health risk is higher. And so is the effect of water pollution on aquatic life.

Pesticides/insecticides/herbicides - comprise a large number of individual chemicals that get into water due to agricultural activities directly (by spraying over large areas) or indirectly with agriculture runoff. The insecticide DDT is a typical example of such type of water pollutant.

PCBs - in spite of their recent ban, their ubiquitous environmental presence makes these contaminants usually associated with urban runoffs.

II) Radiological - when radioactive materials are the water pollutant causes.

III) Biological - when various microorganisms (e.g., bacterial species and viruses), worms, and/or algae occurring in a large number are the water pollution causes. This type of pollution is caused by decaying organic material in water, animal wastes, as well as improper disposal of human wastes.
2. The type (grouping) of the source of water pollutants:
Point sources

These are localized sources like an industrial process, a mining activity, etc. These sources are usually regulated so that the effect may be predicted and the impact minimized. However, accidental leaks and spills are an exception to that.

Non-point sources

These are unidentified sources from which pollutants are carried away by water discharges and runoffs. Non-point pollution may involve a broad range of pollutants, but in lower amounts than the point sources.

Sources of Water Pollution

The main sources of pollution are all resulted from the disposal of chemical substances coming from medical, industrial and household waste, chaotic agricultural fertilizers disposal and accidental oil spills that pollute the water to a large extent.

Examples of major water pollutants that affect the health of humans are:

the numerous infectious agents (bacteria, viruses, and parasites) that contaminate the water through sewage, human waste, and animal excreta

radioactive waste that contains highly toxic materials such as uranium, thorium, and radon. This waste is a major water pollutant resulted from mining activities, power plants or natural sources

the chemical substances that contaminate the water. These chemicals can be either organic - pesticides, plastic, oil, detergents, etc. - coming from domestic, industrial or agricultural waste, or inorganic - acids, metals, salts - domestic and industrial effluents.

Examples of major water pollutants that affect the ecosystem onlyare the following:

plant nutrients like phosphates and nitrates that form various chemical fertilizers, sewage, and manure

oxygen-demanding manures and agricultural waste resulted from sewage and agricultural run-offs

sediments in the soil (silt) following soil erosion, and heated waters used in several industries and power plants.

How Does Water Pollution Affect Us?

Water pollution may cause a large variety of diseases and poses a serious problem for human health. This is mainly because we may get exposed to polluted water in various ways, including, but not necessarily limited to:

Drinking polluted water

Bathing or showering in polluted water

Swimming in polluted water

Breathing the vapors of a polluted water while sitting next to a polluted water source

Consuming polluted food (meat and/or vegetables) affected by polluted water

Consuming meat from animals fed with polluted water of food affected by polluted water (e.g. vegetables irrigated with polluted water or grown in an area with polluted groundwater)

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What Is Water Pollution | Environmental Pollution Centers

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Definition Water pollution is defined as the presence in groundwater of toxic chemicals and biological agents that exceed what is naturally found in the water and may pose a threat to human health and/or the environment. Additionally, water pollution may consist of chemicals introduced into the water bodies as a result of various human activities.