Dissolved Oxygen (DO)
•Measurement of the amount of O2 dissolved in water
•DO < 5 ppm: dangerous for cold water fish
•DO < 1 ppm: anoxic
•Factors affecting DO:
–decomposition, microbial activity, respiration, turbulence, wind, salinity, temperature
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One of the parameters that we measured was dissolved oxygen. Dissolved oxygen concentration in a lake is a measurement of the amount of gaseous oxygen dissolved in the water. Because organisms rely on this oxygen for respiration, water with a DO concentration of less than 5 ppm is considered dangerous for cold water fish. When levels fall below this, fish kill like the one in the picture may occur. When DO concentration falls below 1 ppm, the water is termed anoxic. DO levels are affected by many factors, including decomposition, microbial activity, respiration, turbulence, wind disruption, salinity, and temperature.