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Ozone depletion has slowed, and scientists are hopeful it will recover by mid century.

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Six million people in Pennsylvania and neighboring states get their drinking water from the Susquehanna River. Major pollution sources include agriculture, urban development and industry. Nicholas A. Tonelli, CC BY

America's drinking water infrastructure is aging and in serious need of modernization. Pipes are overdue for replacement, and water and wastewater treatment systems need upgrades to deal with new classes of pollutants. Changing a drinking water standard or adding a new substance to the list of contaminants regulated by the Environmental Protection Agency is time-consuming. Some water systems are having problems meeting current standards, much less upgrading to meet new requirements.

A 2017 Gallup poll found that 63 percent of Americans worry a great deal about drinking water pollution. And a recent report from the Natural Resources Defense Council, Threats on Tap, suggests that they have good reason. According to the report, community water systems - public systems that serve cities and towns year-round - registered more than 80,000 reported violations of the Safe Drinking Water Act in 2015.

As water resource educators with Penn State University's Extension service, our role is to educate the public using research-based information. Most of our work is focused on private water systems - mainly wells and springs, which are used by over 15 million U.S. households. These private systems share many of the critical concerns about public systems addressed in NRDC's national report.

USEPA

Clean water and proper sanitation have greatly improved life expectancy in the United States over the past 150 years. Now, however, we see an urgent need to upgrade water infrastructure, and to update regulations, enforcement and public education about drinking water safety. With many public and private water systems across the nation aging and under stress, it is important for everyone to understand the risks associated with drinking water contamination, and to know how to take simple steps such as having their water tested if they suspect there may be a problem.

Land use and source water protection

Delivering clean drinking water starts with protecting sources, including groundwater and surface rivers and lakes. Many water quality problems that we see in Pennsylvania are based on local land uses. Nitrates from agriculture and development are a particular problem in water wells in the southeast and south-central parts of the state. Exposure to nitrates in drinking water can cause health effects, especially in infants, inhibiting their blood's ability to carry oxygen.

Fertilizer from farm fields, lawns and gardens contributes large amounts of nitrogen to surface and groundwater. Nitrates are very water-soluble and readily move across the land and into groundwater. Pesticides and herbicides do the same if they are not properly applied. Homes in rural areas that use septic systems can also release nitrates if the systems aren't working properly.

In western Pennsylvania, unconventional shale gas drilling has become a major industry since 2009. In late 2016 EPA published a report on how these operations can affect drinking water. Many homeowners near drilling operations are proactively testing their water supplies to get a baseline reading of their well water quality.

Doug Duncan, USGS

When land uses change - for example, energy operations move in, or a farm is sold and developed - nearby residents frequently take a closer look at their source water and watch for impacts within the watershed supply area. Households that use well water face some unique challenges. EPA does not regulate private water supplies. Pennsylvania does not have statewide well construction standards, and only a few municipalities regulate water testing or construction. In general, homeowners with private water systems are solely responsible for testing their water and installing any necessary treatment equipment to correct problems.

We always tell well owners not to apply or dump anything within 100 feet of their well that they don't want to drink, since this area supplies most of the water to their well. On a larger scale, the same advice holds true for public water supplies.

Some communities are creating source water collaboratives to monitor drinking water supplies and address problems. For example, the River Alert Information Network is a regional sourcewater protection program in the Ohio River basin in southwestern Pennsylvania and northern West Virginia. This network of public water systems has set up a real-time monitoring network that can notify drinking water supply intakes downstream of contamination that may be flowing in their direction.

Critical contaminants

Bacterial contamination threatens public and private water supplies. It can happen at the source, during water treatment - especially as systems age - or in the piping systems that deliver water to customers.

Public water systems are required to disinfect water and maintain a secondary level of disinfectant throughout the system to ensure that water delivered to homes is safe. Leaky supply lines cause several types of problems. First, they waste treated water. Second, they can lower water pressure in the system. When this happens, untreated water can seep in, contaminating water that has already been treated.

High-quality construction and maintenance are crucial for private water systems too. We have seen systems that lacked a watertight well cap, allowing insects or surface water to enter the well. Some wells have cracked casings enclosing the well bore hole, or no casing at all, which can allow polluted runoff to contaminate water in the well. When private septic systems fail to properly treat wastewater, bacteria from the wastewater can contaminate the landowner's private well, and may reach aquifers serving other nearby wells and municipal systems.

The water supply crisis in Flint, Michigan has brought new attention to lead contamination and other impacts associated with corrosive water. Similar problems exist in other private and public systems. Most lead contamination comes from supply lines to the home or lead solder in pipes and fixtures within the home.

We receive calls from homeowners concerned about lead in both public and private water supplies. If their home was built before lead solder was banned from plumbing systems in 1991, we recommend testing their water.

NASA Earth Observatory

Monitoring and testing are crucial

We can treat only what we monitor. Over the years, Penn State Extension's research has found that fewer than 50 percent of private water system owners have ever had their water tested. Although we work to educate private water system owners about their responsibility to monitor their water, and recommend testing it annually, many owners only do so when they are concerned about their water's appearance or taste.

Monitoring is just as critical for public water systems, on a much larger scale. The Pennsylvania Department of Environmental Protection has proposed new fees, at EPA's urging, to pay for hiring more inspectors for public water systems that serve more than 10 million residents. This is a step in the right direction but a drop in the bucket compared to current needs.

Protecting source waters and preventing contamination in the first place is even more cost-effective than hiring new inspectors. Pollution is much easier to contain at the source than when it is detected downstream or has already contaminated drinking water supplies.

Safe drinking water is a critical resource. The United States needs to invest in infrastructure, public education, source water protection, regulation and monitoring for new contaminants to keep water flowing to a thirsty nation.

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Is your drinking water safe? Here's how you can find out

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America's drinking water infrastructure is aging and in serious need of modernization. Pipes are overdue for replacement, and water and wastewater treatment systems need upgrades to deal with new classes of pollutants. Changing a drinking water standard or adding a new substance to the list of contaminants regulated by the Environmental Protection Agency is time-consuming.

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Acid rain describes any form of precipitation that contains high levels of nitric and sulfuric acids. It can also occur in the form of snow, fog, and tiny bits of dry material that settle to Earth. Normal rain is slightly acidic, with a pH of 5.6, while acid rain generally has a pH between 4.2 and 4.4.

Rotting vegetation and erupting volcanoes release some chemicals that can cause acid rain, but most acid rain is a product of human activities. The biggest sources are coal-burning power plants, factories, and automobiles.

When humans burn fossil fuels, sulfur dioxide (SO ₂) and nitrogen oxides (NO x) are released into the atmosphere. Those air pollutants react with water, oxygen, and other substances to form airborne sulfuric and nitric acid. Winds may spread these acidic compounds through the atmosphere and over hundreds of miles. When acid rain reaches Earth, it flows across the surface in runoff water, enters water systems, and sinks into the soil.

Sulfur dioxide and nitrogen oxides are not primary greenhouse gases that contribute to global warming, one of the main effects of climate change; in fact, sulfur dioxide has a cooling effect on the atmosphere. But nitrogen oxides contribute to the formation of ground-level ozone, a major pollutant that can be harmful to people. Both gases cause environmental and health concerns because they can spread easily via air pollution and acid rain.

Acid rain has many ecological effects, especially on lakes, streams, wetlands, and other aquatic environments. Acid rain makes such waters more acidic, which results in more aluminum absorption from soil, which is carried into lakes and streams. That combination makes waters toxic to crayfish, clams, fish, and other aquatic animals. ( Learn more about the effects of water pollution.)

Some species can tolerate acidic waters better than others. However, in an interconnected ecosystem, what affects some species eventually affects many more throughout the food chain, including non-aquatic species such as birds.

Acid rain and fog also damage forests, especially those at higher elevations. The acid deposits rob the soil of essential nutrients such as calcium and cause aluminum to be released in the soil, which makes it hard for trees to take up water. Trees' leaves and needles are also harmed by acids.

The effects of acid rain, combined with other environmental stressors, leave trees and plants less healthy, more vulnerable to cold temperatures, insects, and disease. The pollutants may also inhibit trees' ability to reproduce. Some soils are better able to neutralize acids than others. But in areas where the soil's "buffering capacity" is low, such as parts of the U.S. Northeast, the harmful effects of acid rain are much greater.

Acid deposits damage physical structures such as limestone buildings and cars. And when it takes the form of inhalable fog, acid precipitation can cause health problems including eye irritation and asthma.

The only way to fight acid rain is by curbing the release of the pollutants that cause it. This means burning fewer fossil fuels and setting air-quality standards.

In the U.S., the Clean Air Act of 1990 targeted acid rain, putting in place pollution limits that helped cut sulfur dioxide emissions 88 percent between 1990 and 2017. Air-quality standards have also driven U.S. emissions of nitrogen dioxide down 50 percent in the same time period. These trends have helped red spruce forests in New England and some fish populations, for example, recover from acid rain damage. But recovery takes time, and soils in the northeastern U.S. and eastern Canada have only recently shown signs of stabilizing nutrients.

Acid rain problems will persist as long as fossil fuel use does, and countries such as China that have relied heavily on coal for electricity and steel production are grappling with those effects. One study found that acid rain in China may have even contributed to a deadly 2009 landslide. China is implementing controls for sulfur dioxide emissions, which have fallen 75 percent since 2007 -but India's have increased by half.

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Acid rain describes any form of precipitation that contains high levels of nitric and sulfuric acids. It can also occur in the form of snow, fog, and tiny bits of dry material that settle to Earth. Normal rain is slightly acidic, with a pH of 5.6, while acid rain generally has a pH between 4.2 and 4.4.

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Ocean acidification (OA) is spreading rapidly in the western Arctic Ocean in both area and depth, according to new interdisciplinary research in Nature Climate Change by a team of international collaborators, including University of Delaware professor Wei-Jun Cai.

The research shows that, between the 1990s and 2010, acidified waters expanded northward approximately 300 nautical miles from the Chukchi slope off the coast of northwestern Alaska to just below the North Pole. Also, the depth of acidified waters was found to have increased, from approximately 325 feet to over 800 feet (or from 100 to 250 meters).

"The Arctic Ocean is the first ocean where we see such a rapid and large-scale increase in acidification, at least twice as fast as that observed in the Pacific or Atlantic oceans," said Cai, the U.S. lead principal investigator on the project and Mary A.S. Lighthipe Professor of Earth, Ocean, and Environment at UD.

"The rapid spread of ocean acidification in the western Arctic has implications for marine life, particularly clams, mussels and tiny sea snails that may have difficulty building or maintaining their shells in increasingly acidified waters," said Richard Feely, NOAA senior scientist and a co-author of the research. Sea snails called pteropods are part of the Arctic food web and important to the diet of salmon and herring. Their decline could affect the larger marine ecosystem.

Among the Arctic species potentially at risk from ocean acidification are subsistence fisheries of shrimp and varieties of salmon and crab.

Other collaborators on the international project include Liqi Chen, the Chinese lead-PI and scientist with the Third Institute of Oceanography of State Oceanic Administration of China; and scientists at Xiamen University, China and the University of Gothenburg, Sweden, among other institutions.
Pacific Winter Water
The researchers studied water samples taken during cruises by Chinese ice breaker XueLong, (meaning "snow dragon") in summer 2008 and 2010 from the upper ocean of the Arctic's marginal seas to the basins as far north as 88 degrees latitude, just below the North Pole, as well as data from three other cruises.

Scientists measured dissolved inorganic carbon and alkalinity, which allows them to calculate pH and the saturation state for aragonite, a carbonate mineral that marine organisms need to build their shells.

Data collected by ship and model simulations suggest that increased Pacific Winter Water (PWW), driven by circulation patterns and retreating sea ice in the summer season, is primarily responsible for this OA expansion, according to Di Qi, the paper's lead author and a doctoral student of Liqi Chen, the lead PI in China.

"This work will help increase our understanding of climate change, carbon cycling, and ocean acidification in the Arctic, particularly as it affects marine and fishery science and technology," added Chen.

PWW comes from the Pacific Ocean through the Bering Strait and shelf of the Chukchi Sea and into the Arctic basin. In recent years, melting sea ice has allowed more of the Pacific water to flow through the Bering Strait into the Arctic Ocean. Pacific Ocean water is already high in carbon dioxide and has higher acidity. As the ocean mass moves north, it absorbs additional carbon dioxide from decomposing organic matter in the water and sediments, increasing acidity.

The melting and retreating of Arctic sea ice in the summer months also has allowed PWW to move further north than in the past when currents pushed it westward toward the Canadian archipelago.

Arctic ocean ice melt in the summer, once found only in shallow waters of depths less than 650 feet or 200 meters, now spreads further into the Arctic Ocean.

"It's like a melting pond floating on the Arctic Ocean. It's a thin water mass that exchanges carbon dioxide rapidly with the atmosphere above, causing carbon dioxide and acidity to increase in the meltwater on top of the seawater," said Cai. "When the ice forms in winter, acidified waters below the ice become dense and sink down into the water column, spreading into deeper waters."

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fish; marine biology; sea life; nature; global warming; oceanography; geography; climate

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Acidification of Arctic Ocean may threaten marine life, fishing industry

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An international research team found a rapid rise in acidification in the western Arctic Ocean, a potential threat to shellfish, the marine ecosystem and the fishing industry. Since the 1990s, acidified waters have expanded north about 300 nautical miles from Alaska to just below the North Pole.

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Loss of Biodiversity and Extinctions - Global Issues

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The loss of biodiversity is increasing. There is massive extinction from human activity. For example, fish stocks are dwindling, forest loss is resulting in the loss of many species, land and other resources are being misused, leading to various long terms costs.