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Turbidity, measured in NTU (nephelometric turbidity units), is a measure of the clarity of a sample of water. It measures the how much light is scattered by the particles in the water when the sample is subjected to light. Higher turbidities mean that the water is murkier.

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Turbidity - Water Properties, USGS Water Science School

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Turbidity, from the USGS Water Science School.

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Nutrients are elements found in water that are necessary for plant growth. But excess amounts can cause problems. Some nutrients include phosphorus and nitrate.

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Nitrogen and Water: USGS Water Science School

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Nitrogen and water - the U.S. Geological Survey's Water Science School.

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Eutrophication: An increase in algae in the environment often due to excess nutrients in a body of water.
Point-Source Pollution: "Water pollution coming from a single point, such as a sewage-outflow pipe."

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Eutrophication occurs when a body of water receives an excessive nutrient load, particularly phosphorus and nitrogen. This often results in an overgrowth of algae. As the algae die and decompose, oxygen is depleted from the water, and this lack of oxygen in the water causes the death of aquatic animals, like fish.

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Water should not contain more than 10 mg/L of Nitrate or more than .1 mg/L of Phosphorus. There is no defined minimum.

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USGS NAWQA CIRC1136 Nutrients in Nation's Waters

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A method for determining the cloudiness of water. NTU (nephelometric turbidity units), the unit used to determine turbidity, gets its name from nephelometry.

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Nephelometry Readers -Isogen Life Science

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Nephelometry is a method to detect particles in liquid samples. The principle is to measure forwarded scattered light when a laser beam passes through a sample and the light is deflected by the particles.

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Both Nitrate and Phosphorus are expressed in values of milligrams per liter (mg/L).

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USGS NAWQA CIRC1136 Nutrients in Nation's Waters

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The quality of being clear and not having visible particles in water.

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the quality or state of being clear : lucidity; the quality of being easily understood; the quality of being expressed, remembered, understood, etc., in a very exact way... See the full definition

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Water that has a turbidity value of 0 NTU; water completely clear of foreign particles.

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Stormwater that flows over the surface of land until it reaches a larger body of water. This occurs when the land that rain lands on is not permeable.

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What is Stormwater Runoff and Why Do We Need to Reduce It?

Stormwater runoff is rainfall that flows over the ground surface. It is created when rain falls on roads, driveways, parking lots, rooftops and other paved surfaces that do not allow water to soak into the ground. Stormwater runoff is the number one cause of stream impairment in urban areas. Where rain falls on paved surfaces, a much greater amount of runoff is generated compared to runoff from the same storm falling over a forested area. These large volumes of water are swiftly carried to our local streams, lakes, wetlands and rivers and can cause flooding and erosion, and wash away important habitat for critters that live in the stream.

Stormwater runoff also picks up and carries with it many different pollutants that are found on paved surfaces such as sediment, nitrogen, phosphorus, bacteria, oil and grease, trash, pesticides and metals. These pollutants come from a variety of sources, including pet waste, lawn fertilization, cars, construction sites, illegal dumping and spills, and pesticide application. Researchers have found that as the amount of paved surfaces (a.k.a. impervious cover) in the watershed increases, stream health declines accordingly. Click here for a full report on the impacts of impervious cover on streams, lakes and wetlands.

To counteract these impacts of stormwater runoff, most municipalities have adopted regulations that require management of stormwater for all new development. Stormwater management is the use of specific practices, constructed or natural, to reduce, temporarily detain, slow down and/or remove pollutants from stormwater runoff. Stormwater management practices are essentially designed to restore or mimic some of the natural processes provided by the vegetative cover that existed prior to land disturbance. In many regions of the country, this native vegetative cover includes trees and shrubs.

Preserving undisturbed vegetative cover during land development is a much more cost effective approach than destroying these features and having to construct new stormwater management practices to replace the functions they originally provided. Trees, forests and other vegetation and their associated soils are often referred to as "green infrastructure" when they are used to manage stormwater runoff instead of or in addition to pipes, pumps, storage chambers or other "hard infrastructure." Municipalities are beginning to realize the many stormwater benefits of green infrastructure, and are encouraging the use of stormwater management practices that conserve forests and incorporate vegetative features. EPA's green infrastructure website provides a wealth of information on this topic.

How Do Trees Reduce and Remove Pollutants from Stormwater Runoff?

Trees and forests improve stream quality and watershed health primarily by decreasing the amount of stormwater runoff and pollutants that reaches our local waters. Trees and forests reduce stormwater runoff by capturing and storing rainfall in the canopy and releasing water into the atmosphere through evapotranspiration. In addition, tree roots and leaf litter create soil conditions that promote the infiltration of rainwater into the soil. This helps to replenish our groundwater supply and maintain streamflow during dry periods.

The presence of trees also helps to slow down and temporarily store runoff, which further promotes infiltration, and decreases flooding and erosion downstream. Trees and forests reduce pollutants by taking up nutrients and other pollutants from soils and water through their roots, and by transforming pollutants into less harmful substances. In general, trees are most effective at reducing runoff from smaller, more frequent storms.

In addition to these stormwater benefits, trees provide a host of other benefits such as improved air quality, reduced air temperatures in summer, reduced heating and cooling costs, increased property values, habitat for wildlife, and recreation and aesthetic value.

The City of Vancouver, Washington recognizes the important connection between forests and stormwater runoff and have included Urban Forestry in the City's stormwater management plan, which represents a comprehensive watershed approach to improving water quality. In addition, 100% of the stormwater utility fees collected are used to support the Urban Forestry Division.

How Do We Measure and Provide 'Credit' for Stormwater Runoff Reduction by Trees?

So, if trees are so great, why isn't everyone using them to meet their stormwater management needs? One of the reasons is that developers have no incentive to use them unless they can get credit for it and most municipalities do not provide these credits. Municipalities that do provide credits may not provide enough to act as a true incentive.

A stormwater credit system reduces the stormwater management requirements a developer has to meet in exchange for conserving forests or using site design techniques that reduce the amount of paved surfaces created. The credit system directly translates into cost savings for the developer by reducing the size of stormwater management practices that must be constructed. A 2014 report by Stone Environmental summarizes the different approaches to stormwater crediting systems for trees across the country.

In most municipalities around the country with stormwater management regulations, site designers are required to capture and remove pollutants from a specified runoff volume and control the maximum (or peak) rate of runoff from the site for certain size storm events. Under this scenario, water quality 'treatment' is defined solely by the pollutant removal functions of the stormwater management practices used, and does not account for their ability to reduce the overall volume of runoff. A number of states and communities are beginning to recognize that there are benefits of shifting from this peak-based stormwater control to an approach that focuses on reducing the volume of runoff (though re-use, evapotranspiration, or infiltration) leaving a site. A volume reduction approach is most appropriate for the relatively small, frequent storms, which matches up well with the stormwater benefits provided by trees. Click here for more on the runoff reduction approach adopted by the State of Virginia.

Reducing runoff volume using green infrastructure has benefits beyond just removing pollutants. It also recharges groundwater, provides better protection of sensitive aquatic resources, and reduces the size and cost of hard infrastructure that would otherwise need to be constructed. One challenge with this approach has been how to account for the runoff reduction provided by green infrastructure in rainfall/runoff models commonly used by engineers. Click here for a summary of how to account for trees and other green infrastructure in stormwater models and calculators.

What Are Some Specific Practices That Use Trees to Reduce Stormwater Runoff?

The most effective way to minimize the impacts of stormwater runoff described above is to limit the amount of paved surfaces that are created during development, and preserve as much as possible the natural topography and vegetation. Specifically, existing forests can be protected during construction and permanently managed as conservation lands. In cases where there are no existing forest stands (e.g., development of a former farmland), reforestation can help to offset these impacts.

The impacts of stormwater runoff can also be minimized by increasing tree canopy over paved surfaces to increase interception of rainfall. Another way to minimize impacts is by "disconnecting" paved surfaces so that they no longer drain to the system of gutters, inlets and pipes that make up the storm drainage system and ultimately flow to our local streams and rivers. Disconnection can involve redirecting runoff from rooftops or individual parking lots to stormwater management practices or vegetated areas and allowing the runoff to slowly soak into the ground.

Most stormwater management practices that incorporate vegetation have relied primarily on herbaceous vegetation with few trees and shrubs. The reason for this is that engineers are often concerned that tree roots, branches and leaves will compromise the effectiveness or stability of the practice. When trees are planted in stormwater management practices, they often die because of harsh conditions or they are removed by maintenance crews or overzealous homeowners.

To address these concerns, the Center for Watershed Protection and the USDA Forest Service held a series of workshops attended by stormwater engineers, foresters, arborists, soil scientists, landscape architects and other experts that resulted in the development of new designs for stormwater management practices. The goal of the workshops was to identify potential limitations to planting trees in stormwater management practices, both from an engineering perspective and from the standpoint of tree survival and health. The resulting designs for so-called "stormwater forestry practices" were intended to address these limitations through design modifications, species selection, or other methods. A major goal of these designs is to harness the numerous benefits of trees to increase the effectiveness of stormwater practices, while providing other benefits to the community, such as cooling and shade, aesthetics, and wildlife habitat. The conceptual designs are provided in Cappiella et al. (2006).

References

Cappiella, K., Schueler, T., and T. Wright. 2006. Urban Watershed Forestry Manual. Part 2: Conserving and Planting Trees at Development Sites. NA-TP-01-06. USDA Forest Service, Northeastern Area State and Private Forestry. Newtown Square, PA.

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What is Stormwater Runoff and Why Do We Need to Reduce It? Stormwater runoff is rainfall that flows over the ground surface. It is created when rain falls on roads, driveways, parking lots, rooftops and other paved surfaces that do not allow water to soak into the ground.

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The process in which water wears down the surface of the earth. Water can pick up soil particles as it flows over soil, and can break down rocks that it is running over.

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Erosion definition, the act or state of eroding; state of being eroded. See more.

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Most turbidimeters can only calculate values between 0-40 NTU. However, water can have a much higher turbidity than 40 NTU. If the water sample is above 40 NTU, the sample must be diluted by adding reagent water until it is below 40 NTU. The actual turbidity can then be calculated by multiplying the measured turbidity by the total volume of water in the sample. The Environmental Protection Agency states that drinking water should not have a turbidity over 5 NTU, and   recommends that it is less than 1 NTU.
https://www.epa.gov/sites/production/files/2015-08/documents/method_180-1_1993.pdf

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05. What are EPA?s drinking water regulations for pathogens and indicators like turbidity?

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In 1974, Congress passed the Safe Drinking Water Act. This law requires EPA to determine the level of contaminants in drinking water at which no adverse health effects are likely to occur. These no...

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The unit used to measure turbidity is NTU (nephelometric turbidity units). Turbidimeters generally calculate values from 0-40 NTU. The higher the value, the murkier the water is. The value is determined by shining a bright light on a water sample at a 90 degree angle. The more that the light is scattered by the particles in the water, the higher the turbidity. A sample that is measured at 0 NTU means that the light passed through the sample without being scattered.

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To help categorize the differences in turbidity probe design and distinguish among turbidity measurements that may not be comparable, new units of measurement were established in 2004 and assigned based on the probe design. The following table summarizes the units and the characteristics of the probes assigned to those units.

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Nitrate and Phosphorus are released through point-source pollution, namely through wastewater-treatment facilities. In addition, Nitrate cant be released into the atmosphere from runoff contaminated by fertilizer, from through automobiles.

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Nitrogen and Water: USGS Water Science School

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Nitrogen and water - the U.S. Geological Survey's Water Science School.

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Too many nutrients in an atmosphere can cause the ecosystem to be imbalanced, as excess algae built up through eutrophication dies, depleting oxygen from the water, and killing many aquatic animals. Nitrates also have the ability to kill people, especially if a young child drinks the contaminated water.

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Nitrogen and Water: USGS Water Science School

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Nitrogen and water - the U.S. Geological Survey's Water Science School.

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There are a few human causes of unnatural changes of turbidity levels. One human activity that causes the turbidity of nearby bodies of water to increase is construction. When construction projects are started, the area that is being worked on is completely cleared until there is just soil left. Because there is nothing holding the soil down, runoff from storms can erode soil particles and carry them into larger bodies of water which increases turbidity. Another human causes the raises turbidity is agriculture. When an area of land is cleared of natural vegetation before a farmer plants his crops, runoff can carry soil particles into other bodies of water and increase the turbidity. One human activity that actually lowers turbidity is building dams. Dams cause the turbidity of the water downstream of the dam to decrease.

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download: doc/pdf

Current TEKS:

8.14 C: describe how human activities have modified soil, water, and air quality

Future TEKS:

8.8 B analyze effects of weathering, erosion, and deposition on the environment in ecoregions of Texas

8.8 C: model the effects of human activity on surface water in a watershed

Scope and Sequence:

Aldine: Grade 8, 2nd six weeks Cy-Fair: Grade 8, 4th six weeks

Turbidity is a measure of the cloudiness or murkiness of water caused by suspended solids, and is an indicator of water quality. The individual suspended particles are often too small to be seen by the naked eye, but higher levels of particles lead to more turbid waters. Turbidity is analogous to smoke in air. The particles are a result of weathering of soils and rocks that enter the body of water through the process of erosion.

http://www.physics.utoronto.ca/~nonlin/turbidity/tcurrent3.jpg

Turbidity is measured using a Secchi disk. A Secchi disk is a circular disk with an alternating black and white pattern that is attached to a string or pole that is used to measure water clarity by being lowered into water until the disk is no longer visible. A reading is then taken in centimeters. This serves as a measurement of water transparency (clarity).

http://dipin.kent.edu/images/Secchi%20Disk.jpg

Turbidity of rivers and lakes is dynamic. Turbidity responds to a variety of factors: such as dominant rock types and plant cover of the drainage basin, phytoplankton population, bottom-feeders, flood events, as well as land use, dams and construction. Throughout the course of a river, the turbidity level will vary because of changes in these factors.

Human activities impact the turbidity of rivers and subsequently the water quality. Numerous human activities have an impact on river turbidity. Construction activities normally strip the land of vegetation. Despite preventative measures, storm water tends to carry sediment off the site and into surrounding streams and rivers, thereby increasing the turbidity. Once construction is completed, the smooth paved surfaces allow runoff water to gain more energy. This causes the water to become more erosive and carry sediment farther into streams and rivers. Agricultural activities have a similar effect. The land is cleared of native vegetation and storm water is able to carry sediment away. Human-constructed dams often have an opposite effect: they tend to decrease turbidity downstream of the dam. Water flow slows behind a dam, and sediments are able to settle. Only a reduced amount of sediment will pass through the dam when water is released.

If water has an elevated degree of turbidity for a sustained period, river and lake ecosystems can suffer detrimental effects. Sustained below or above-average turbidity will cause a change in the ecosystem of streams, rivers and lakes. Increased turbidity will cause less light to reach the bottom of the river, stream or lake, thereby making survival difficult for bottom-dwelling organisms dependent on sunlight. Also, sediment particles will absorb heat from the sun, making highly turbid waters warmer than less turbid waters. Higher temperatures also cause a decrease in oxygen content of the water. Thus, an increase in temperature resulting from turbidity will cause sensitive organisms to perish.

Sediment Input: Sediment input into a stream and lake from cleared strip of land

Note: Figures for this case study are located in the following powerpoint file: Navasota_River_Maps.ppt

The Navasota River is a tributary of the Brazos River, and runs from its headwaters near Groesbeck, Texas until it flows into the Brazos River west of Navasota, Texas (Fig. 1; Fig. 8). It has been observed that turbidity increases downstream of where the river crosses a major construction site along State Highway 6 near Navasota. This study examines data taken in the field: turbidity and map data including: geology, precipitation, soil type, ecoregion, and relation to construction site (upstream or downstream) to identify possible trends associated with increased turbidity levels. Sampling locations spanned from near the headwaters of the Navasota River to the mouthwaters where it flows into the Brazos River. The Navasota River runs through the following seven counties: Limestone, Robertson, Leon, Madison, Brazos, Grimes, and Washington. While erosion controls are in place, they do not prevent additional erosion due to construction altogether. We believe that the main source of an increase in turbidity in the Navasota River is caused by the highway construction.

Samples were taken at 4 locations along the Navasota River and 1 along the Brazos River very close to the intersection of the Navasota and Brazos Rivers (Fig. 8). Turbidity measurements were made with a Secchi disk at each site. Each site was characterized for ecoregion, geology, annual precipitation, soil type, watershed/tributaries, and its relation to the construction site using data collected in the field, data from the Texas Bureau of Economic Geology, and data from the Texas Natural Resource Information System (TNRINS).

Table 1. Data from Sampling Sites and Maps

Downstream from the construction site, the Navasota River has experienced a greater degree of turbidity. The decrease in water transparency (increase in turbidity) as measured by the Secchi disk from Site 4 to Site 5 is approximately 2.5 times greater than the difference between Sites 3 and 4 (Table 1). The geology of the study area is predominantly Cenozoic aged sediments (Fig. 2). The strata are increasingly younger as the river flows farther South. Bedrock is more limestone dominated towards the northern portion of the river, but detrital sediments are preeminent towards the southern portion of the river. Soil type directly adjacent to the river is characterized by clay (Fig. 3). Surrounding the river, soils alternate between loam (a mix of sand, silt, and clay) to fine sand. The Navasota River flows through two Texas ecoregions: Oakwoods and prairie and blackland prairie (Figs. 4, 5). Precipitation has only a slight variation over the study area from 38 to 40 inches per year (Figs. 6, 7). Tributaries of the Navasota River are distributed in a normal pattern with no significant increase of decrease in number of tributaries throughout the entire watershed (Fig. 9).

We believe the increased turbidity is due to a greater input of sediment from human activities. The geology of the study site does not significantly vary through the course of the Navasota River, and thus there appears to be no correlation between the large increase in turbidity and geology. Additionally, the soil type remains constant throughout the course of the river. The Navasota River flows through two different ecoregions. The difference in ecoregion could account for the increase in turbidity, but this is unlikely due to the fact that the soil types do not change. The annual precipitation is only slightly variable, and does not suggest a major trend because it is only a minor increase in rainfall and could account for an increase in turbidity, but does not account for such a large increase in turbidity. While logically we can expect waters downstream to be more turbid because of introduction of a larger amount of sediments from tributaries, there does not appear to be a distinct trend of a large increase of tributaries upstream of site 5 and downstream of site 4. The only observable pattern between the dramatic change in turbidity and the parameters surveyed is the presence of construction.

Good Research Questions:

What other parameters (besides precipitation, annual rainfall, etc.) could affect turbidity and how could we test them?

This question allows students to analyze a real system as scientists do. Earth scientists seldom have simple cause and effectrelationships as the natural world is multi-facted and interacting. An example of an additional parameter that could be tested is biodiversity.

How does the Navasota River compare turbidity to other rivers in the area, like the Brazos River?

This question would give students a basis of comparison to see if the trend of construction zone increasing turbidity is valid outside of the Navasota River case and help further support our hypothesis.

Not So Good Research Questions:

What is the temperature of turbid waters?

This question yields simple numerical answers. It does not lead to further discussion unless linked to other related questions.

Simulated Research Activities:

Dataset: Navasota River Dataset - dataset including turbidity readings, ecoregion, geology, soil type, and position relative to construction site (upstream or downstream) to be used in conjunction with the maps ( Navasota_River_Maps.ppt)

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IRC: Human Impact on Water - River Water Turbidity

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download: doc/pdf 8.14 C: describe how human activities have modified soil, water, and air quality 8.8 B analyze effects of weathering, erosion, and deposition on the environment in ecoregions of Texas 8.8 C: model the effects of human activity on surface water in a watershed Aldine: Grade 8, 2nd six weeks Cy-Fair: Grade 8, 4th six weeks Turbidity is a measure of the cloudiness or murkiness of water caused by suspended solids, and is an indicator of water quality .

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High turbidity in bodies of water can affect the environment in negative ways. High turbidity can hurt fish ecosystems in many ways. Freshwater fish can be killed by the particles in the water and fish eggs do not develop the same way. It can also affect the migration pattern of certain fish, and cause them to not migrate. High turbidity also decreases the amount of food available to fish because plants and algae can not survive in highly turbid waters. Fish can also lose their ability to fight diseases and their growth rate can decrease. In addition to hurting fish ecosystems, turbid bodies of water are not as aesthetically pleasing as clear waters.

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Dissolved Oxygen is the microscopic bubbles of gaseous oxygen mixed into the water and used by organisms within the water. Aquatic plants release oxygen back into the water as a byproduct of photosynthesis.

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Brings water and air in close contact in order to remove dissolved gases (such as carbon dioxide) while also oxidizing any materials like iron.

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The process by which a plant uses carbon dioxide, water, and sunlight to produce its own food, then releasing oxygen as a byproduct. Plants in water cause the water to increase int dissolved oxygen.

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Photosynthesis is the process plants, algae and some bacteria use to turn sunlight, carbon dioxide and water into sugar and oxygen.

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The amount of a substance that will dissolve in another substance. The solubility of the oxygen is effected by temperature and salinity, or salt level.

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Solubility definition is - the quality or state of being soluble.

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To increase a concentration beyond its saturation point. In terms of dissolved oxygen two main things can push it to supersaturation, rapid aeration and rapid temperature increase.

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Information about supersaturated solutions for An Introduction to Chemistry by Mark Bishop

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Water reaches equilibrium towards 100% air saturation, dissolved oxygen levels also change with temperature, salinity and pressure changes. Therefore, dissolved oxygen levels can range from less than 1 mg/L to more than 20 mg/L depending on how all of these factors interact with each other. Though much of the level depends on the season, location, and depth when referring to a fresh body of water. Some states, like Michigan, enacted requirements to have minimum concentration levels of dissolved oxygen like 7 mg/L for cold-water fisheries and 5 mg/L for warm-water fisheries. In salt water it ranges from 9 mg/L at the poles to 4 mg/L at the equator usually.

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The unit to measure dissolved oxygen is in dissolved oxygen concentrations of milligrams per-liter or (mg/L). The higher the value the more saturated the water is with oxygen. Dissolved oxygen is dependent on water temperature meaning colder water can hold more dissolved oxygen.

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Dissolved oxygen, from the USGS Water Science School: All about water.

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Dissolved oxygen, from the USGS Water Science School; All about water.

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There are little to no human direct causes to affecting the dissolved oxygen levels. A few ways humans could affect would be through clearing land, point source pollution, nutrient pollution, and destruction. When clearing land it could send excess matter into streams it could cause the micro organisms to use more oxygen than can be replaced. Point sources like discharge could lead into waterways and be decomposed by bacteria leading to areas of low dissolved oxygen downstream. Nutrient pollution can cause excess plant and algae growth more bacteria that eat dead plant material use oxygen. Finally, destruction can decrease the amount of shade and warm the water, warmer water can't hold as much dissolved oxygen as cooler water can.

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WHAT IS DISSOLVED OXYGEN?

The oxygen that makes aquatic life possible does not form bubbles, nor is it the oxygen that is part of the H ₂O water molecule. It is a separate O ₂ molecule that is dissolved in the water and invisible to our eyes.

WHY CARE ABOUT DISSOLVED OXYGEN?

All terrestrial and aquatic animals need oxygen to survive. Many aquatic macroinvertebrate species depend on oxygen-rich water. Without sufficient oxygen they may disappear. Even a small change in dissolved oxygen concentration can affect the composition of aquatic communities. Many fish require a certain dissolved oxygen range in order to survive

Utah Standards

Minimum dissolved oxygen concentration for warm-water fish: 5.5 mg/L

Minimum dissolved oxygen concentration for cold-water fish: 6.5 mg/L

NATURAL FACTORS INFLUENCING DISSOLVED OXYGEN

Aquatic life- Animals living in water use up dissolved oxygen. Bacteria take up oxygen as they decompose materials. Dissolved oxygen levels drop in a water body that contains a lot of dead, decomposing material.

Elevation- Since streams get much of their oxygen from the atmosphere, streams at higher elevations will generally have less oxygen.

Salinity (saltiness)- Salty water holds less oxygen than fresh water.

Temperature- Cold water holds more dissolved oxygen than warm water.

Turbulence- More turbulence creates more opportunities for oxygen to enter streams.

Aquatic Vegetation- Aquatic vegetation and algae directly release oxygen into the water during photosynthesis (during the day). At night, plants actually use oxygen for their metabolism.

Riparian Vegetation (plants along the stream)- Riparian vegetation shade the stream, decreasing water temperatures, and as temperature decreases dissolved oxygen increases.

HUMAN FACTORS INFLUENCING DISSOLVED OXYGEN

Clearing Land (e.g., construction, logging) - This may send excess organic matter into streams. Organic matter is decomposed by microorganisms, which use up oxygen in the process.Therefore, if there is a lot of organic waste in the stream, the microorganims use more oxygen than can be replaced in the stream.

Point source pollution - Sewage effluent and factory discharge into waterways can be decomposed by bacteria as above, leading to areas of low DO downstream.

Nutrient pollution - Nutrient pollution can cause excess plant and algae growth. As above, the bacteria that eat dead plant material consume oxygen from the water.

Destruction of riparian areas (e.g., development or overgrazing) decreases the amount of shade and increases the water temperature. Warmer water holds less DO (Dissolved Oxygen) than colder water.

Learn ways to limit human influences: Protect Your Water

HOW DO WE MEASURE DISSOLVED OXYGEN?

Utah Water Watch- Learn how volunteers across the state measure Dissolved Oxygen. Select the Tier 1 tab for basic/classroom-friendly procedures, or select the Tier 2 tab for more advanced procedures.

Stream Side Science- Explore different lesson plans involving Dissolved Oxygen and see how they apply to the different core curriculums for grades k-12.

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The oxygen that makes aquatic life possible does not form bubbles, nor is it the oxygen that is part of the H 2O water molecule. It is a separate O 2 molecule that is dissolved in the water and invisible to our eyes. All terrestrial and aquatic animals need oxygen to survive.

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There are many environmental consequences from dissolved oxygen with one being the aquatic life. Fish are highly dependent on the water to regulate themselves so if the dissolved oxygen levels were to exceed 110% can have a chance in the fish getting gas bubble disease where the bubbles block the flow of blood through blood vessels causing death. On the other end of the spectrum, if levels drop too low, like 1-2 mg/L for only a few hours it can can lead to the death of large amounts of fish, meaning the lower and longer the dissolved oxygen levels are, the more stress that is put on the aquatic life.

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Why is important the oxygen dissolved in water

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Biological Advantages of the oxygen dissolvec in water