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B. Dissolved Gases 1. Oxygen – Dissolved Oxygen (DO) vital to aquatic life Sources that ↑ DO

B. Dissolved Gases 1. Oxygen – Dissolved Oxygen (DO) vital to aquatic life Sources that ↑ DO atmosphere or aeration from riffles (water over rocks) Photosynthesis (peaks during afternoon). Temperature affects DO: ↑ temp means ↓ DO ↓ temp means ↑ DO

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B. Dissolved Gases 1. Oxygen – Dissolved Oxygen (DO) vital to aquatic life Sources that ↑ DO

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  1. B. Dissolved Gases 1. Oxygen – Dissolved Oxygen (DO) vital to aquatic life Sources that ↑ DO atmosphere or aeration from riffles (water over rocks) Photosynthesis (peaks during afternoon)

  2. Temperature affects DO: ↑ temp means ↓ DO ↓ temp means ↑ DO (decomposition of organic matter wastes with ↑ temps) Other DO effects include pollutants such as acid mine drainage, sewage or agricultural runoff

  3. Recommended DO level for aquatic life is above 5ppm

  4. Mayfly nymph

  5. Caddisflies

  6. 2. Carbon Dioxide- vital to plants sources to ↑ CO2: atmosphere groundwater decomposition sources to remove CO2 photosynthesis organisms absorb in form of carbonates in shells

  7. C. pH Measure of the hydrogen ion concentration (H+) PA streams are slightly acidic due to 1. acid rain 2. rocks in PA contain minerals 3. coal mines (AMD) Fortunately, many PA streams have good buffering capabilities

  8. Is a pH of 5 more or less acidic than a pH of 6? More acidic How much more acidic? 10 x

  9. D. Alkalinity – measure of water’s ability to neutralize acids Helps maintain pH at optimum level Determined by types of soil and bedrock through which the water passes Streams with limestone have ↑ alkalinity

  10. E. Nitrates – in streams occurs as nitrate (NO3 ) nitrite (NO2 ) and ammonia (NH3 ) Nitrate enters stream from fertilizer runoff, septic systems or manure runoff Excess nitrates will cause rapid plant growth When excess plants die, decomposition uses large amount of DO

  11. F. Iron Excess iron from acid mine drainage ( remember: pyrite is iron sulfide, yellow boy is ferric hydroxide) Iron precipitates (solids) clog gills and suffocate bottom dwelling invertebrates

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