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- OH- OH- H+ OH- H+ H+ H+ OH- H+ H+ H+ OH- H+ H+ OH- OH- H+ 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). • -The higher the TDS or free ions, the more electrical current that can occur, causing higher conductivity. 134 uS
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. ACID