Eutrophication - An Excess Nutrients in Water

Too Much is Not Always Good

Eutrophication is characterized by excessive plant and algal growth due to the increased availability of one or more limiting growth factors needed for photosynthesis such as sunlight, carbon dioxide, and nutrient fertilizers. Eutrophication occurs naturally over centuries as lakes age and are filled in with sediments.

However, human activities have accelerated the rate and extent of eutrophication through both point-source discharges and non-point loadings of limiting nutrients, such as nitrogen and phosphorus, into aquatic ecosystems, with dramatic consequences for drinking water sources, fisheries, and recreational water bodies. People nowadays do not realize that this kind of problem exist and a very critical crisis in the surface bodies of water.

There are three main structural factors that influence and accelerated the rate of eutrophication:

Using of fertilizers - Farmers used fertilizers very often in order to have a good and healthy crops (organic though) in the soil to accumulate nutrients. To much of these nutrients specifically the nitrogen and phosphorus is no longer able to assimilate them and they are carried by rain into rivers and groundwater that flow into lakes or seas.
Discharge of waste water into water bodies - This factor seems to be very critical one because most industrial, domestic and residential waste are often discharged in the surface water without being treated properly and usually they don't have any wastewater treatment plant facilities. This wastewater is rich and high of nutrients that can be very detrimental to the receiving surface water.
Lack of Self Purification Capacity - Lakes or any stagnant surface water usually have their own limits to purify and clean themselves because they are not flowing and usually the dilution factor and aeration is not like in the sea, ocean or river.

The enrichment of water with nutrients such as nitrogen and phosphorus will cause a conspicuous effects in:

The creation of dense blooms of noxious
Foul-smelling phytoplankton that reduce water clarity and harm water quality
Algal blooms limit light penetration, reducing growth and causing die-offs of plants in littoral zones

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Lowering the success of predators that need light to pursue and catch prey.
It can also affect the human consumption (food)
Ecotourism and recreational aquatic activities