Elaborate BOD. BOD is an index of water pollution. Explain.

Explanation

The amount of oxygen required for microbial breakdown of biodegradable organic matter is called BOD. It is higher in polluted water and lesser in drinking water. When large amount of sewage water enters into the ponds, rivers, lakes, seas and oceans, it reduces the amount of free oxygen. This depletes the respiratory oxygen levels and causes suffocation for aquatic fauna there by killing aquatic life. BOD is measured to assess the quality of water with respect to the amount of organic load.