eutrophication


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eutrophication

(yo͞otrō'fĭkā`shən), aging of a lake by biological enrichment of its water. In a young lake the water is cold and clear, supporting little life. With time, streams draining into the lake introduce nutrients such as nitrogen and phosphorus, which encourage the growth of aquatic organisms. As the lake's fertility increases, plant and animal life burgeons, and organic remains begin to be deposited on the lake bottom. Over the centuries, as silt and organic debris pile up, the lake grows shallower and warmer, with warm-water organisms supplanting those that thrive in a cold environment. Marsh plants take root in the shallows and begin to fill in the original lake basin. Eventually the lake gives way to bogbog,
very old lake without inlet or outlet that becomes acid and is gradually overgrown with a characteristic vegetation (see swamp). Peat moss, or sphagnum, grows around the edge of the open water of a bog (peat is obtained from old bogs) and out on the surface.
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, finally disappearing into land. Depending on climate, size of the lake, and other factors, the natural aging of a lake may span thousands of years. However, pollutants from man's activities can radically accelerate the aging process. During the past century, lakes in many parts of the earth have been severely eutrophied by sewage and agricultural and industrial wastes (see water pollutionwater pollution,
contamination of water resources by harmful wastes; see also sewerage, water supply, pollution, and environmentalism. Industrial Pollution
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). The prime contaminants are nitrates and phosphates, which act as plant nutrients. They overstimulate the growth of algae, causing unsightly scum and unpleasant odors, and robbing the water of dissolved oxygen vital to other aquatic life. At the same time, other pollutants flowing into a lake may poison whole populations of fish, whose decomposing remains further deplete the water's dissolved oxygen content. In such fashion, a lake can literally choke to death.

eutrophication

[yü·trə·fə′kā·shən]
(ecology)
The process by which a body of water becomes, either by natural means or by pollution, excessively rich in dissolved nutrients, resulting in increased primary productivity that often leads to a seasonal deficiency in dissolved oxygen.
References in periodicals archive ?
Thus, the aim of the present study was to analyse the effect of increasing crop yields on future coastal eutrophication.
The first signs of eutrophication in the Baltic Sea sediments are detected in the mid-1800s, although eutrophication strongly intensified only after the early to mid-1900s (Andren et al.
Eutrophication, for example, is a result of nutrient loads that have accumulated for over a century, originating e.
Keywords: eutrophication, spatio-temporal analysis, water contamination, degradation of wetland, Lake Kalar Kahar
In an attempt to evaluate eutrophication in tropical areas, several indices that consider the particular characteristics of tropical environments were also developed.
The objective of this research was to determine the sites within the Spring Lake watershed most likely to damage Spring Lake by increasing the eutrophication rate.
Eutrophication is the ecosystem's response to the addition of artificial or natural substances, mainly phosphates, through detergents, fertilisers, or sewage, to an aquatic system.
Depending on the degree of eutrophication, subsequent negative environmental effects such as anoxia (oxygen depletion) and severe reductions in water quality may occur, affecting fish and other animal populations.
Amongst the causes being examined are pollution or a lack of oxygen due to eutrophication.
In a report, published on 18 October on the implementation of the directive concerning the protection of waters against pollution caused by nitrates from agricultural sources, known as the Nitrates Directive - COM(2013)0683(1), the European Commission points out that while nitrate concentrations are slightly decreasing in surface waters and in groundwater and even though sustainable agricultural practices are more widespread, pollution by nitrates and eutrophication are still posing a problem in numerous member states.
In semiarid regions some studies demonstrated changes in the trophic state of water sources, through human practices and occupation of watersheds which may raise nitrogen and phosphorus levels, which in turn can lead to the eutrophication and poor quality of the water of lakes, rivers and reservoirs (CHELLAPPA et al.