CLASSIFICATION OF POLLUTANT

A. Based on degradation

a. Biodegradable pollutants: Biodegradable pollutants get broken down under natural conditions due to the action of micro-organisms. Therefore they are considerably less harmful. They behave as pollutants only in very large quantities. Examples: excreta, sewage, etc.

b. Non-biodegradable pollutants: Cannot be broken down under natural conditions by the action of micro-organisms or they take an extremely long time to be broken down. Examples: Common plastics, DDT, metal wastes such as lead, mercury, arsenic, etc.

B. Based on the absorption capacity of the Environment

a. Stock pollutants: Pollutants that the environment has little or no absorptive capacity are called stock pollutants (eg. persistent synthetic chemicals, non-biodegradable plastics, and heavy metals). Stock pollutants accumulate in the environment over time. The damage they cause increases as more pollutant is emitted, and persists as the pollutant accumulates. Stock pollutants can create a burden for future generations by passing on damage that persists well after the benefits received from incurring that damage have been forgotten.

b.Fund pollutants:

Fund pollutants are those for which the environment has some absorptive capacity. Fund pollutants do not accumulate in the environment unless the emission rate exceeds the receiving environment’s absorptive capacity (eg. carbon dioxide, which is absorbed by plants and oceans). Fund pollutants are not destroyed, but rather converted into less harmful substances, or diluted/dispersed to non-harmful concentrations.