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Water Chemistry Project

Water Chemistry Project. In order to evaluate water changes, we need access to reliable information on current and past conditions. If changes are already taking place, comparing multiple sites at different areas can help us understand what is happening.

uriel-middleton
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Water Chemistry Project

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  1. Water Chemistry Project In order to evaluate water changes, we need access to reliable information on current and past conditions. If changes are already taking place, comparing multiple sites at different areas can help us understand what is happening.

  2. Some of the Factors that influence Water Quality are: • Source • Amount • Land use • Location

  3. Source Location From where? underground Land Use Or surface How much?

  4. Testing Water Quality • Water quality parameters • often tested are: • Dissolved oxygen • Water temperature • pH • phosphate • Nitrate • Turbidity • BOD Water test kit

  5. Dissolved Oxygen and Photosynthesis/Respiration photosynthesis 6CO2 + 6H2O + light energy  C6H12O6 + 6O2 respiration C6H12O6 + 6O2  6CO2 + 6H2O + heat energy

  6. Dissolved Oxygen: • Oxygen can enter water directly from the atmosphere and is produced during photosynthesis by plants and algae. • It is removed from the water by plants and algae during respiration and by the decay of organic matter. • Oxygen concentrations may be affected by water temperature, pressure, and salinity, as well as by the density of fish populations and by plant and algae photosynthesis, respiration, and decay.

  7. Dissolved Oxygen: • Cold water can dissolve more oxygen than warm water. For example, at 25˚ C, dissolved oxygen solubility is 8.3 mg/L, whereas at 4˚ C the solubility is 13.1 mg/L. • As temperature goes up, water releases some of its oxygen into the air.

  8. Water temperature = active z z z = z z z inactive

  9. Temperature • Water temperatures have an effect on which species are able to live in a particular area. • Temperatures may also affect animals’ feeding and reproduction habits, as well as the water’s capacity to hold dissolved oxygen (cold water can dissolve more oxygen than warm water). • Temperatures change naturally throughout the day and are also affected both by natural factors such as shade cover and snow melt and by human factors such as industrial discharge and surface runoff.

  10. Dissolved oxygen and water temperature Oxygen meter dissolved oxygen and water temperature usually vary over a 24 hour cycle. Surface dissolved oxygen, mg/L Surface water temperature, C 31 15 29 10 summer 27 5 25 0 6 a.m. noon 6 p.m. midnight 6 a.m.

  11. pH pH is a measure of acidity (hydrogen ion concentration) in water or soil. pH = - log [ H+ ] 2 6 14 0 1 3 4 5 7 8 9 10 11 12 13 neutral acid alkaline

  12. pH • Different species of aquatic life can tolerate different pH ranges; however most species prefer water that is relatively close to neutral pH, or 7.0. • Extremes in pH can make water uninhabitable or may affect feeding and reproduction. • pH levels may be affected by human factors such as mining drainage and industrial discharge.

  13. Nitrite/Nitrate NH4++1.5 O2 + Nitrosomonas NO2- + 0.5 O2 + Nitrobacter NO3- nitrite nitrate feces Bacterial decomposition

  14. Nutrients: • Nutrients such as nitrogen and phosphorous are present in water naturally, from animal waste and decaying organic matter. • These nutrients can sometimes build up in water both from natural sources and from human factors, including sewage, fertilizer runoff, detergents, and industrial discharge. • This buildup of nutrients is called eutrophication. • High levels of nutrients may spur the growth of algae and aquatic plants, which can lead to oxygen depletion due to respiration and decay by the plants or algae.

  15. Phosphates • The element phosphorus is necessary for plant and animal growth. • When it rains, varying amounts of phosphates wash from farm soils into nearby waterways. Phosphates stimulate the growth of plankton and water plants that provide food for fish. • This may increase the fish population and improve the waterway’s quality of life. • If too much phosphate is present, algae and water weeds grow wildly, choke the waterway, and use up large amounts of oxygen. Many fish and aquatic organisms may die.

  16. Phosphate levels 0.01-0.03 mg/L Amount of phosphate-phosphorus in most uncontaminated lakes 0.025 mg/L Accelerates the eutrophication process in lakes 0.1 mg/L Recommended maximum for rivers and streams

  17. Turbidity Effects on Fish and Aquatic Life • Water plants need light for photosynthesis. If suspended particles block out light, photosynthesis—and the production of oxygen for fish and aquatic life—will be reduced. • If light levels get too low, photosynthesis may stop altogether and algae will die. It’s important to realize conditions that reduce photosynthesis in plant result in lower oxygen concentrations and large carbon dioxide concentrations. Respiration is the opposite of photosynthesis.

  18. Biological Oxygen Demand (BOD) • A measure of the oxygen used by microorganisms to decompose waste. • If there is a large quantity of nutrients in the water supply, there will also be a lot of bacteria present working to decompose this waste. • In this case, the demand for oxygen will be high (due to all the bacteria) so the BOD level will be high. • When BOD levels are high, dissolved oxygen levels decrease because the oxygen that is available in the water is being consumed by the bacteria.

  19. How water quality values are expressed as:

  20. Analysis of Test Results • For each test performed research what an acceptable value would be for your water source. • If any of your tests deviate from acceptable levels suggest reasons for this result and ways to correct them.

  21. Determining the WQI • http://www.indiana.edu/~bradwood/eagles/wqi.htm • This site will help you calculate and overall WQI and interpret the results.

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