Term: Dissolved Oxygen

Dissolved Oxygen

Dissolved oxygen is the amount of molecular oxygen dissolved in water. It is required for the respiration of aerobic microorganisms. However, oxygen is only slightly soluble in water.The actual quantity of oxygen (other gases too) that can be present in solution is governed by;

•the solubility of gas
•the partial pressure of the gas in the atmosphere
•the temperature
•the concentration of the impurities in the water (e.g., salinity, suspended solids, etc.)

The amount of DO decreases with increasing water temperature. So a cool or cold water can contain much more DO than the warm water. As a result, aquatic life in streams and lakes is placed under more oxygen stress during summer months than during the other seasons.