PLUME

(1) (Ecology) A space in air, water, or soil containing pollutants released from a point source. (2) (Water Pollution) A relatively concentrated mass of emitted chemical contaminants spreading in the environment. In surface water, the effluent added to a receiving stream near a point source. For example, when a heated-water discharge is added to a stream, the heated water does not mix immediately with the stream water. The mass of hot water remains detectable for some distance downstream. In groundwater, the Leachate leaking down-gradient from a site of buried waste material.