| A | B |
|---|
| pollution | contamination of the air, water, or soil with undesirable amounts of materials or heat. |
| point source | specific points of origin of pollutants, such as factory drains or sewage outlets. |
| nonpoint source | sources of pollution such as general runoff of sediments, fertilizers,pesticides, and other materials from farms and urban areas as opposed to specific points of discharge |
| erosion | the process of soil particles being taken away by wind or water. |
| sheet erosion | when surface runoff flows down a slope or across a field in a wide sheet peeling off fairly uniform layers of soil. |
| rill erosion | when surface runoff forms fast-flowing rivulets of water that cut small channels in the soil. |
| gully erosion | when rivulets of fast flowing water join together with each succeeding rain cutting channels wider and deeper until they become ditches or gullies |
| runoff | freshwater from precipitation or melting ice that flows on the earth's surface into nearby streams, lakes, wetlands, and reservoirs. |
| watershed | the total land area that drains directly or indirectly into a particular stream or river. |
| anthropogenic | referring to pollutants and other forms of impacts on natural environments that can be traced to human activities. |
