Temperature and DO

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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

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Why is Temperature Important?

• Most aquatic organisms are poikilothermic
  (cold-blooded), which means they dont
  internally regulate their core body temperature.
• The rate of many chemical reactions increases at
  higher temperatures.
• Oxygen solubility

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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 0C 32F 273.15 K
• Water Boils at 100C 212F 373.15 K

0C
100C
32F
212F
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Temperature - Units

• Conversion Factors
• (F 32)
• 1.8
• F (C x 1.8) 32

C
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Temperature Q10 Rule

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

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Temp Biological Effects
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Temperature Standards
Rolling 7-day average of maximum daily
temperatures
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Temperature Deep Cr (Clack)
21.3
21.0
20.9
20.9
20.9
20.5
20.2
19.4
7-day max AVG 20.6C
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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

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Dissolved Oxygen

• O2 gas dissolved in water
• Required by nearly all aquatic life

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DO Solubility

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

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DO Solubility
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DO Units

• Concentration
• mg/L µg/mL ppm (parts per million)
• Percent Saturation
• DO Sat.

Measured DO (mg/L) Solubility (mg/L)
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DO Sources

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

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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

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DO Diel Fluctuations
PM
Dissolved Oxygen
AM
Time of Day
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DO Standards
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DO and Temp Data Quality
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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