2 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 7Alkaline – pH more than 7Neutral is 7
3 pH and Water QualityVery high or low pH values are toxic to life in the stream6.5 to 8.2 is optimal for most organismsFactors that affect pHAcid Rain (magnitude and frequency)Area geology – Dissolved Minerals (limestone)Algal BloomsIndustrial or Commercial SourcesCarbonic Acids from Respiration and Decomposition
5 Dissolved Oxygen Oxygen gas dissolved in the water Vital for the existence of aquatic organismKey component in cellular respiration for both aquatic and terrestrial life.Factors to affect DO levelsAquatic plant populations (diversity and volume)Decaying organic matterCurrent velocityAtmospheric PressureHuman Activity
6 DO and Water Quality The larger the organism, the more DO it requires. Trout need 6.5 mg/LMosquito Larvae need 1.0 mg/LSources of DOAtmospheric Diffusion (air touching the water)Aeration of water (white water)Photosynthesis of primary producers (plants)Higher in the day or night??
8 Nitrates and Phosphates Necessary nutrients for aquatic plants and algae (only small amounts needed)Excessive amounts = eutrophicationTwo types – Organic and InorganicOrganic (human or animal waste)Inorganic (fertilizers and detergents)
9 Nutrients and Water Quality High levelsEutrophication of aquatic ecosystemIncreased algal bloomsDecreased DONitrates and Phosphates easily dissolve in water (percolation and runoff enable this)Common sources – Factories, urban runoff, farms, decomposition of plants and animals
12 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)
13 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 CFactors to Affect TemperatureAir tempAmount of ShadeSoil erosion (too much sediment)Human Activity (power plants)Where streams meet
15 Others Parameters Not Discussed BOD – Biological Oxygen DemandTDS – Total Dissolved SolidsSpecific ConductivityTurbidity
16 Homework ProjectEach group should pick one factor and research it thoroughlyDiscuss 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)
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