Water Quality Indicators A selection

pH Relative concentration of (in water) Hydrogen ions H+ Hydroxide ions OH- pH Scale is logarithmic (as you go up on the scale, it increases by a factor of 10) Acid – pH less than 7 Alkaline – pH more than 7 Neutral is 7

pH and Water Quality Very high or low pH values are toxic to life in the stream 6.5 to 8.2 is optimal for most organisms Factors that affect pH Acid Rain (magnitude and frequency) Area geology – Dissolved Minerals (limestone) Algal Blooms Industrial or Commercial Sources Carbonic Acids from Respiration and Decomposition

Base Line pH

Dissolved Oxygen Oxygen gas dissolved in the water Vital for the existence of aquatic organism Key component in cellular respiration for both aquatic and terrestrial life. Factors to affect DO levels Aquatic plant populations (diversity and volume) Decaying organic matter Current velocity Atmospheric Pressure Human Activity

DO and Water Quality The larger the organism, the more DO it requires. Trout need 6.5 mg/L Mosquito Larvae need 1.0 mg/L Sources of DO Atmospheric Diffusion (air touching the water) Aeration of water (white water) Photosynthesis of primary producers (plants) Higher in the day or night??

Fish Kills

Nitrates and Phosphates Necessary nutrients for aquatic plants and algae (only small amounts needed) Excessive amounts = eutrophication Two types – Organic and Inorganic Organic (human or animal waste) Inorganic (fertilizers and detergents)

Nutrients and Water Quality High levels Eutrophication of aquatic ecosystem Increased algal blooms Decreased DO Nitrates and Phosphates easily dissolve in water (percolation and runoff enable this) Common sources – Factories, urban runoff, farms, decomposition of plants and animals

Nitrogen Cycle

Algal Bloom

Water Temperature How warm or cool the water is Abnormal temperatures are toxic to aquatic life (too warm or cold) Small changes can have a huge impact (even 1 degree) Temperature affects DO levels (warm=less and cool=more)

Temperature and Water Quality Warm Temps – Thermal Pollution – will kill fish and increase photosynthesis (algal blooms) Example: Trout 5-20 degrees C, Caddisfly Larvae 10 to 25 degrees C Factors to Affect Temperature Air temp Amount of Shade Soil erosion (too much sediment) Human Activity (power plants) Where streams meet

Human Activity

Others Parameters Not Discussed BOD – Biological Oxygen Demand TDS – Total Dissolved Solids Specific Conductivity Turbidity

Homework Project Each group should pick one factor and research it thoroughly Discuss examples of how that factor affected a stream, lake or pond. Next Tuesday, May 10, you will present your findings to the class (powerpoint or posterboard)