Pollutants when released in the environment gain entry into the soil by adsorption, into the water by dissolution and into the air by evaporation. To cause environmental degradation and evince its undesirable effects a pollutant has to enter the system. If they are unable to do so they stayasa separate entity in the medium concerned, such as a heap of garbage lying in waste dumps or the particulate matter which floats up, stays suspended or settles down in an aquatic medium. As such they form inert packages of pollutants in the environment.