Dissolved Oxygen Content

( Article Type: Explanation )

Dissolved oxygen content (DOC) is an important means of measuring the ‘health’ of a stretch of river or quantity of water by checking the concentration of oxygen. The healthier the water body is, the higher the dissolved oxygen content will be. A level of 8–9 mg/l (milligrams of oxygen per litre of water) could be expected in a normal stream, whereas 4 mg/l and below are situations where it is very difficult for organisms to survive and usually means that there are some forms of pollution present. Dissolved oxygen content is usually measured in mg/l (milligrams per litre) or mg/m3 (micrograms per cubic metre).

The relationship between dissolved oxygen content within water and the biological oxygen demand (BOD) of the organisms within a body of water helps us to understand the carrying capacity of organisms for that particular stretch of water. Studies of aquatic ecosystems consider BOD and DOC when trying to determine management strategies for these systems. The addition of high BOD wastes to an aquatic ecosystem can have disastrous effects upon the system and its ability to support life.