What causes eutrophication?

The main causes of eutrophication are an increase in the concentration of nutrients to an ecosystem. Increased nutrient enrichment can arise from both point and non-point sources:

• Point source pollution: Pollution that comes from contaminants that enter a waterway from a single identifiable source such as stationary locations or fixed facilities. Examples are discharges from a sewage treatment plant or industrial plants and fish farms.
• Non-point source pollution: Pollution from widespread including human activities with no specific point of discharge or entry into receiving watercourses. Examples are leaching out of nitrogen compounds from fertilized agricultural lands and losses from atmospheric deposition.

The enrichment of water by nutrients can be of a natural origin (natural eutrophication) but is often dramatically increased by human activities (cultural or anthropogenic eutrophication). Natural eutrophication has been occurring for millennia. It is the process of addition, flow and accumulation of nutrients to water bodies resulting in changes to the primary production and species composition of the community.

References

1. Causes, historical development, effects and future challenges of a common environmental problem: eutrophication. De Jonge, V.N.; Elliot, M.; Orive, E. (2002). Hydrobiologia 475-476:1-19.
2. Source apportionment of nitrogen and phosphorus inputs into the aquatic environment. European Environment Agency (2005). EEA Report, 7 Office for Official Publications of the European Communities: Luxembourg. ISBN 92-9167-777-9.48 pp.
3. Eutrophication and health. European Commission (2002). Office for Official Publications of the European Communities: Luxembourg. ISBN 92-894-4413-4.28 pp.