| Abstract from DBPedia | Eutrophication is the process by which an entire body of water, or parts of it, becomes progressively enriched with minerals and nutrients, particularly nitrogen and phosphorus. It has also been defined as "nutrient-induced increase in phytoplankton productivity". Water bodies with very low nutrient levels are termed oligotrophic and those with moderate nutrient levels are termed mesotrophic. Advanced eutrophication may also be referred to as dystrophic and hypertrophic conditions. Eutrophication can affect freshwater or salt water systems. In freshwater ecosystems it is almost always caused by excess phosphorus. In coastal waters on the other hand, the main contributing nutrient is more likely to be nitrogen, or nitrogen and phosphorus together. This depends on the location and other factors. When occurring naturally, eutrophication is a very slow process in which nutrients, especially phosphorus compounds and organic matter, accumulate in water bodies. These nutrients derive from degradation and solution of minerals in rocks and by the effect of lichens, mosses and fungi actively scavenging nutrients from rocks. Anthropogenic or "cultural eutrophication" is often a much more rapid process in which nutrients are added to a water body from a wide variety of polluting inputs including untreated or partially treated sewage, industrial wastewater and fertilizer from farming practices. Nutrient pollution, a form of water pollution, is a primary cause of eutrophication of surface waters, in which excess nutrients, usually nitrogen or phosphorus, stimulate algal and aquatic plant growth. A common visible effect of eutrophication is algal blooms. Algal blooms can either be just a nuisance to those wanting to use the water body or become harmful algal blooms that can cause substantial ecological degradation in water bodies. This process may result in oxygen depletion of the water body after the bacterial degradation of the algae. Approaches for prevention and reversal of eutrophication include: minimizing point source pollution from sewage, and minimizing nutrient pollution from agriculture and other nonpoint pollution sources. Shellfish in estuaries, seaweed farming and geo-engineering in lakes are also being used, some at the experimental stage. It is important to note that the term eutrophication is widely used by both scientists and public policy-makers, giving it a myriad of definitions.富栄養化（ふえいようか、英語: eutrophication）とは、海・湖沼・河川などの水域が、貧栄養状態から富栄養状態へと移行する現象を言う。ここで「栄養」とは水中の栄養塩（窒素化合物やリンなど）であり、植物プランクトンにとって水面付近で光合成し繁殖するために必要な栄養）のことを指す。
* 自然富栄養化：形成されたばかりの池や湖が、遷移によって湖沼型を変化させてゆく過程。
* 人為的富栄養化：近年では、人間活動の影響による水中の肥料分（窒素化合物やリンなど）の濃度上昇を意味する場合が多い。水域の富栄養化の要因は生活工業排水や農業の肥料、畜産の糞尿など多岐に渡る。このような富栄養化は生態系における生物の構成を変化させ、一般には生物多様性を減少させる反面、基礎生産の向上により生物生産性が増加する方向に作用する。富栄養化がすすんだ過栄養状態の水域では、赤潮や青潮などの現象を二次的に引き起こす為、富栄養化は公害や環境問題として広く認識されている。 (Source: http://dbpedia.org/resource/Eutrophication) |
