The process of eutrophication happens when natural as well as artificial nutrients, mostly nitrates and phosphates, find their way into an aquatic or terrestrial ecosystem. When these nutrients are added to a water body or soil the consequences can show up in numerous forms. One that flourishes when there is extra nutrients is the growth of the microscopic organisms known as phytoplankton (blue-green algae) in freshwater rivers and lakes. When there is an overabundance of them in a lake or river they show up as a green color on top of the water. Excessive algae bloom and weeds are two other results that can also appear when too many nutrients enter a water body. There are two types of eutrophication, natural and cultural, that occur in water bodies. Natural eutrophication occurs at a much slower rate and can take up to a century for results to be seen. Whereas, cultural eutrophication is the more damaging of the two and usually transpires within a few decades. This is due to the excessive accumulation of nutrients at a much faster speed caused by human error. Cultural eutrophication happens when surface run-off, that contains nitrates and phosphates, moves from one place to another, ending up in a river or lake. Unfortunately, there are times when these nutrients end up being leached into the groundwater. At times eutrophication may be severe enough that it causes the oxygen in these water bodies to become quite low. The results of this is seen in the harmful effect it has on aquatic wildlife, creating what is referred to as dead zones. Cultural eutrophication is a problem that is seen universally. Things are being done to fight the spread of eutrophication, along with trying to reverse the damage it has caused to the aquatic ecosystem. Politicians and government agencies have passed legislation that deals with the chemicals that enter water bodies. Conservationists, environmentalists, and those who enjoy or depend on rivers and lakes are also effected by cultural eutrophication and can help to play a role in keeping water bodies healthy.
Causes of Cultural Eutrophication
There are several ways that chemicals can get into water bodies. These are often referred to as point source and non-point sources and are recognized by United States statutes. Research by Smith, Tilman and Nekola (1999) supports this,
Sources of point and nonpoint chemical inputs recognized by US statutes (from Carpenter et al., 1998, modified from Novotny and Olem, 1994)_______________________________________
Wastewater effluent (municipal and industrial)
Run-off and leachate from waste disposal sites
Run-off and infiltration from animal feedlots
Run-off from mines, oil fields, and unsewered industrial sites
Storm sewer outfalls from cities with populations >100,000
Overflows of combined storm and sanitary sewers
Run-off from construction sites with an area >2 ha
Run-off from agriculture (including return flows from irrigated...