. . Classification of Pollutants In terms of eco-system, pollutants can be classified into two basic groups – Non- degradable and degradable. Based on the time taken to breakdown into their ingredients, degradable pollutants are classified as rapidly degradable (non-persistent) and slowly degradable (persistent).
a) Rapidly degradable or non-persistent pollutants: These can be broken down by natural processes. Domestic sewage and vegetable waste are examples of such pollutants. b) Slowly degradable or persistent pollutants: These are pollutants that remain in the environment for many years in an unchanged condition and take decades or longer to degrade, as in the case of DDT. c) Non-degradable pollutants : These cannot be degraded by natural processes.
Once they are released into the environment, they are difficult to be eliminated and Lightning Volcanoes Wildfires Fertilizer Industry, power plants, Sewage treatment Cities Airplanes, Cars, Trucks, Buses and Three & Two wheelers Oil & Gas Natural Area Stationary Transport Pollutant emissions Fig. . Sources of air pollution. XII Std Zoology Chapter XII Std Zoology Chapter Environmental Issues • Area sources – agricultural - wood / stubble burning, fireplaces • Natural sources – wind-blown dust, wildfires, volcanoes.