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Temperature and DO

Temperature and DO. Temperature A measure of heat Dissolved Oxygen (DO) The concentration of oxygen (gas) which is dissolved in water. Both are important individually and to one another. Why is Temperature Important?.

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Temperature and DO

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  1. Temperature and DO Temperature • A measure of heat Dissolved Oxygen (DO) • The concentration of oxygen (gas) which is dissolved in water. Both are important individually and to one another

  2. Why is Temperature Important? • Most aquatic organisms are poikilothermic (“cold-blooded”), which means they don’t internally regulate their core body temperature. • The rate of many chemical reactions increases at higher temperatures. • Oxygen solubility

  3. Temperature - Units • Fahrenheit (°F), Celsius (°C), Kelvin (K) • Celsius (°C) used for most science (SI unit) • a.k.a. centigrade, where “centi-” = hundredth • Water Freezes at 0°C = 32°F = 273.15 K • Water Boils at 100°C = 212°F = 373.15 K 0°C 100°C 32°F 212°F

  4. Temperature - Units • Conversion Factors (°F – 32) 1.8 °F = (°C x 1.8) + 32 °C =

  5. Temperature – Q10 Rule • General rule which predicts: Growth rates of cold-blooded aquatic organisms and many biochemical reaction rates will double for every 10°C (18°F) temperature increase within their "preferred" range.

  6. Optimum Lethal Growth Rate 0 10 20 30 40 50 Temperature (Celsius) Temp – Biological Effects

  7. Temperature Standards Rolling 7-day average of maximum daily temperatures

  8. Temperature – Deep Cr (Clack) 21.3 21.0 20.9 20.9 20.9 20.5 20.2 19.4 7-day max AVG = 20.6°C

  9. Temperature – Causes • Loss of riparian shading • Warm water inputs • Retention ponds • Municipal or industrial wastewater • Stormwater runoff • Groundwater inputs • Weather • Air temperature, cloud cover, day length • Turbidity

  10. Dissolved Oxygen • O2 gas dissolved in water • Required by nearly all aquatic life

  11. DO – Solubility • Inverse, non-linear relationship to temperature • Decreases with decreasing barometric pressure • Weather, elevation • High salinity reduces solubility

  12. DO – Solubility

  13. DO – Units Concentration: mg/L = µg/mL = ppm (parts per million) Percent Saturation: DO % Sat. = Measured DO (mg/L) Solubility (mg/L)

  14. DO – Sources • Photosynthesis • Influenced by sunshine, temperature, water velocity • Atmospheric Re-aeration • Turbulent mixing • Water velocity and depth • Oxygen deficit • Inflow of oxygenated water

  15. DO – Sinks • Respiration • Greatest source of DO loss in summer • Biochemical Oxygen Demand (BOD) • Decomposition of organic wastes • Standard measure is 5-day BOD = BOD5 • Nitrification (NBOD) • NH3 + O2 = NO3

  16. DO – Diel Fluctuations PM Dissolved Oxygen AM Time of Day

  17. Salmonid Spawning thru Fry Emergence Water Quality Standard > 11 mg/L Intergravel Standard > 6 mg/L unless Intergravel DO > 8 mg/L > 9 mg/L or Natural conditions > 95% sat. Cold-water Aquatic Resources > 8 mg/L Natural conditions > 90% sat. Cool-water Aquatic Resources > 6.5 mg/L Warm-water Aquatic Resources > 5.5 mg/L DO – Standards

  18. DO and Temp Data Quality

  19. Measuring DO and Temp • Measure Immediately - In Field • Measure Both at Same Time • Recording Time is Crucial • Sample Collection • Below surface ~ 4 inches (or ½ way to bottom of shallow stream) • Cap DO bottle underwater

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