Water Quality: The Basics NSTA Regional Conference Omaha, Nebraska October 19th, 2005 Why is Water Quality Important? •Effects all humans Safe drinking water Allows for food productions and SAFE food products •Effects Wildlife Health domestic and wild animals Diversity of Life (insects or macroinvertebrates) •Recreation Swimming Water Sports Fishing What determines the Quality of Water? Individual test parameters: • pH • Temperature • Dissolved Oxygen • Clarity Turbidity Secchi • Total Nitrogen • Total Phosphorus • Salinity • Alkalinity pH pH: Negative logarithm of the hydrogen ion concentration pH = -log [H+] H+ OH- H+ H+ H+ OH- OH- H+ OH- H+ H+ OH- OH- H+ H+ OH- H+ H+ OH- H+ H+ Each whole pH below 7 is ten times more acidic than the next higher value. For example, a pH of 4 is ten times more acidic than a pH of 5. The same holds true for pH values above 7. Each value above 7 is ten times more basic than the next lower pH value. Temperature Important because: • Dissolved Oxygen Temperature = Dissolved Oxygen -Decreases in Dissolved Oxygen can cause problems for wildlife (ex. fish kills) •Fluctuations can cause problems for many plants …which moves up the food web. Dissolved Oxygen A measure of free O2 (gas) in the water. <5 ppm – dangerous zone 5 – 10 ppm – adequate zone >10 ppm – good Clarity Turbidity A measure of the suspended solids, which reduce the transmission of light through scattering or absorption. Secchi Measuring how far down a person can see the secchi disk. Somewhat objective, but fairly accurate. Easy to discuss results among non-scientists. Nitrogen •Nitrogen is a nutrient, like calcium or potassium. •Nitrogen is available in the environment naturally. •The problem is when more is added – fertilizers or confinements. Phosphorus • Phosphorus is also a nutrient, like nitrogen, calcium, or potassium. • It is also available in the environment naturally, but phosphorus is more limiting in freshwater ecosystems. • Adding too much phosphorus (making it no linger limiting) • can cause algal blooms. Salinity • A measurement of the salt content in the water < 5 psu = freshwater > 5 psu = brackish water > 32 psu = sea water • Not necessarily “table salt” (NaCl)… - Examples of salts: sodium calcium magnesium, potassium, sulfate, and chloride. - All dissolved from geologic materials … rocks…the bottom of the lake. Conductivity •A measure of the electromagnetic charge of the water. •Measures the electrical charge between two electrodes (metal rods) in the water. -For there to be an electrical charge, there must be free ions or dissolved salts (TDS). 134 uS -The higher the TDS or free ions, the more electrical current that can occur, causing higher conductivity. Alkalinity • The ability of a lake (or body of water) to buffer from changes in pH. • Causes in changes in pH: discharge plant productivity animal waster, processes • Why is alkalinity important? Drastic or constant changes in pH can cause problems for the biota of the lake’s ecosystem. Questions?
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