Eutrophication

 

Eutrophication: The process by which a body of water acquires a high concentration of nutrients, especially phosphates and nitrates. These typically promote excessive growth of algae. As the algae die and decompose, high levels of organic matter and the decomposing organisms deplete the water of available oxygen, causing the death of other organisms, such as fish. Eutrophication is a natural, slow-aging process for a water body, but human activity greatly speeds up the process.

 

 

The runoff of nitrate and phosphate into lakes and streams fertilizes them, and causes accelerated eutrophication  or enrichment of the waters.

Eutrophication  occurs as lakes age. However, human-caused, accelerated eutrophication (called "cultural eutrophication") occurs more rapidly, and causes problems in the affected water bodies, as described below. It is estimated that 50-70% of all nutrients reaching surface water (principally N and P) originate on agricultural land as fertilizers or animal waste.