Question

What is the importance of measuring the BOD of a water body?

Answer 1

Hint: BOD stands for biological oxygen demand. The word talks for itself i.e. it is the demand of oxygen required by the microorganisms, bacteria etc. present in the waterbody. This demand of oxygen is given a term which is dissolved oxygen (DO).

Complete answer:
Let us first gather some information about BOD. Biological oxygen demand or BOD is a measure of oxygen required by aerobic decomposers for the biochemical degradation of organic materials i.e. biodegradable material in water. As the BOD increases, the DO decreases I.e. it portrays that the relationship between the two is inversely proportional. BOD tells us about the intensity of organic pollution in water. Usually a high BOD in a water stream signifies that high levels of nutrients are present, along with a high number of microorganisms feeding on the nutrients.
Just above we came across this term dissolved oxygen, this is the amount of oxygen available for biochemical activity within a given volume of water, expressed as mg/L. Organic and inorganic waste decrease the dissolved oxygen content of the water bodies.
From the above discussion we have understood that the BOD of a water body is important for us to know so that we don’t degrade the water body to an extent that the survival of aquatic organisms becomes problematic. It might be a surprise for all of you that only 10 molecules of oxygen are required per million of water. But, still due to environmental stress and human activities it’s maintenance is becoming difficult.

Note –
If the dissolved oxygen content of a water body is 8.0 mg/L then it may be considered contaminated.
4.0 mg /L dissolved oxygen represents that the water body is highly polluted.
The repercussions of high BOD is the same as of low dissolved oxygen.