Define the following:
(a) Eutrophication
(b) Biological magnification
  (C) Biochemical oxygen demand.

Explanation

(a) Eutrophication: It is a natural process of a water body due to nutrient enrichment.
(b) Biological magnifications: It refers to increase in concentration of the toxicant at successive trophic levels.This happens because a toxic substance accumulated by an organism cannot be metabolised or excreted.
(c) Biochemical oxygen demand: The amount of oxygen that would be consumed if all the orgnic matter in one liter of water were oxidised by bacteria is known as Biochemical oxgyen demand. It decereases the avilbale dissolved oxgyen in water.