The Eutrophication of lakes.
Eutrophication is defined as ¡§the aging of a lake by the biological enrichment of its water¡¨ (encyclopedia.com). This biological enrichment is caused by the addition of nutrients. There is natural eutrophication and cultural eutrophication. Cultural eutrophication is usually defined as the over-enrichment of lakes and rivers with nutrients, usually phosphorous, leading to excessive growth of algae and other aquatic plants. Cultural eutrophication is becoming more common with increased agricultural activity and development of cities around lakes. At first, when a lake is young and just has been formed, the water is usually cold and clear. These conditions support little life but with time drainage of streams into the lake add new compounds, including phosphorous and nitrogen compounds. Natural eutrophication can take many years. On the other hand, cultural eutrophication is a relatively fast process. Human settlement near lakes causes a great increase in nutrient input to the lake. In addition, sewage and wastes are usually thrown into nearby streams that drain into the lake and further increase the nutrient supply. The main nutrients that are present in cultural eutrophication are P and N containing compounds coming from sewage. Some algae and blue-green bacteria can live off of these compounds and rapidly grow in number. This phenomenon is called algal blooming. Eventually, the rate in growth is so great that it becomes unsustainable in natural systems.
Since eutrophication is a worldwide phenomenon and is of great importance economically, much effort and money has been put into creating models to experiment with lake manipulation. Hoping eventually to come up with an answer to stop or slow the process eutrophication. In 1968, Richard A. Vollenweider developed a practical model to compare European and North American lakes. His model consists of the trophic status of a lake, which he says is ¡§a function of the rate of areal...
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