1. Dissolved Oxygen in the River

2. Solubility of gases
 Depends on three factors:
 1) temperature
 2) pressure
 3) aeration

3. Temperature
 If you increase the temperature you
decrease the solubility of a gas.

4. Pressure
 If you increase the pressure you
increase the solubility of a gas.
 -example- pop cans-
 When you open it the pressure
decreases so the gas fizzes out.

5. Aeration
 Mixing or movement causes more gas to dissolve
because of increased surface area exposed to the gas.

6. Dissolved O2 and N2 in water
 Too little oxygen- fish die
-caused by many hot days is a row
- oxygen levels fall below lower limit
for survival.

7.  Too much oxygen and nitrogen (110%
to 124% saturation)
Gas bubble disease
 Nitrogen-gas bubbles block the flow of
blood.
 Diagnosed by gas bubbles in the gills of
the dead fish
 Can occur at the base of a dam.