Dissolved oxygen

Abstract

Dissolved oxygen (DO) is the amount of elemental oxygen (Chemical symbol O2, molecular wt 31.99 g/mol) dissolved in fresh or salt waters. It is measured as mg/L or ml/L for environmental regulatory purposes but is usually measured in uMol for chemical and oceanographic studies. The maximum amount of DO in water at equilibrium with the atmosphere (100 % saturation) depends on the atmospheric pressure (partial pressure) of oxygen and the temperature and salinity of the water. As temperature and salinity increase, dissolved oxygen saturation decreases, while increases in atmospheric pressure increase saturation concentration. Dissolved oxygen concentration is not conservative and is strongly affected by biological processes such as photosynthesis and respiration.