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Eutrophication is a general term describing a process in which nutrients accumulate in a body of water, resulting in an increased growth of organisms that may deplete the oxygen in the water. [ 1 ] [ 2 ] Eutrophication may occur naturally or as a result of human actions.
It is a primary cause of eutrophication of surface waters (lakes, rivers and coastal waters), in which excess nutrients, usually nitrogen or phosphorus, stimulate algal growth. [1] Sources of nutrient pollution include surface runoff from farm fields and pastures, discharges from septic tanks and feedlots, and emissions from combustion.
Diffuse source pollution from agricultural fertilizers is more difficult to trace, monitor and control. High nitrate concentrations are found in groundwater and may reach 50 mg/litre (the EU Directive limit). In ditches and river courses, nutrient pollution from fertilizers causes eutrophication. This is worse in winter, after autumn ploughing ...
Oxygen depletion, resulting from nitrogen pollution and eutrophication, is a common cause of fish kills. Ecosystems Water pollution is a major global environmental problem because it can result in the degradation of all aquatic ecosystems – fresh, coastal, and ocean waters. [ 75 ]
Phosphates have low toxicity in the environment but cause nutrient pollution, a major water quality problem in many watersheds. [17] Phosphates in water cause eutrophication of algae which creates conditions favorable to formation of harmful algal blooms. These blooms prevent light and oxygen from getting into the water, leading to the death of ...
[2] [33] [34] Eutrophication is a well-documented abrupt change from clear water to murky water regimes, which leads to toxic algae blooms and reduction of fish productivity in lakes and coastal ecosystems. [33] [35] [36] Eutrophication is driven by nutrient inputs, particularly those coming from fertilizers used in agriculture. It is an ...
Approximately 78% of Earth's atmosphere is N gas (N 2), which is an inert compound and biologically unavailable to most organisms.In order to be utilized in most biological processes, N 2 must be converted to reactive nitrogen (Nr), which includes inorganic reduced forms (NH 3 and NH 4 +), inorganic oxidized forms (NO, NO 2, HNO 3, N 2 O, and NO 3 −), and organic compounds (urea, amines, and ...
Gradual environmental changes through eutrophication or global warming can cause major oxic-anoxic regime shifts. Based on model studies this can occur abruptly, with a transition between an oxic state dominated by cyanobacteria , and an anoxic state with sulfate-reducing bacteria and phototrophic sulfur bacteria .