Aquatic Pollution and Coastal Management

Unit 1 : Classification of aquatic pollution

1.4.Sources of pollution

The loading of contaminants to surface waters, groundwater, sediments and drinking water occurs via two primary routes: (1) point source pollution and (2) non point-source pollution.

Point source pollution

This originates from discrete sources whose inputs into the aquatic systems can often be defined in a spatially explicit manner. Examples of point-source pollution include industrial effluents (pulp and paper mills, steel plants, food processing plants), municipal sewage treatment plants and combined sewage-storm water overflows, resource extraction (mining) and land disposal sites (landfill sites, industrial impoundments).

Non-point source pollution

In contrast it originates from poorly defined, diffuse sources that typically occur over broad geographical scales. Examples of non-point source pollution include agricultural runoff (pesticides, pathogens, fertilizers), storm water and urban runoff, and atmospheric deposition (wet and dry deposition of persistent organic pollutants such as polychlorinated biphenyls, mercury).