Eutrophication

The stages in eutrophication are:

1. Nitrates from farmland fertilisers and silage, factories or sewage works etc drain into a pond or a river. (see the Nitrogen Cycle)
2. Plants grow rapidly, particuarly on the surface
3. Plants beneath the surface die
4. These plants are decomposed by bacteria and funghi
5. All the oxygen is used up
6. Most animals beneath the surface die as they can't respire.

© Daniel Wilson 2001