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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.
PCLake is designed to study the effects of eutrophication on shallow lakes and ponds. [4] On one hand, the model is used by scientists to study the general behavior of these ecosystems. For example, PCLake is used to understand the phenomena of alternative stable states and hysteresis, and in that light, the relative importance of lake features ...
Eutrophication can be a natural process and occurs naturally through the gradual accumulation of sediment and nutrients. Naturally, eutrophication is usually caused by the natural accumulation of nutrients from dissolved phosphate minerals and dead plant matter in water. [29] [30] Natural eutrophication has been well-characterized in lakes.
A lake is usually classified as being in one of three possible classes: oligotrophic, mesotrophic or eutrophic. Lakes with extreme trophic indices may also be considered hyperoligotrophic or hypereutrophic (also "hypertrophic"). The table below demonstrates how the index values translate into trophic classes.
In lakes, phosphorus and nitrogen are the most common limiting nutrients of primary production and ecosystem respiration. Foundational work on the positive relationship between phosphorus concentration and lake eutrophication resulted in legislation that limited the amount of phosphorus in laundry detergents, among other regulations.
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. [44] 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 ...
Warmer water in lakes, oceans, reservoirs and rivers can cause more eutrophication. This results in more frequent harmful algal blooms. [8]: 140 Higher temperatures cause problems for water bodies and aquatic ecosystems because warmer water contains less oxygen. [60] Permafrost thawing leads to an increased flux of contaminants. [61]