Eutrophication 54840 224938491 2008-07-11T02:31:29Z Geronimo20 332930 add cat {{Pollution}} '''Eutrophication''' is an increase in chemical [[nutrient]]s -- typically compounds containing [[nitrogen]] or [[phosphorus]] -- in an [[ecosystem]]. It may occur on land or in [[water]]. The term is however often used to mean the resultant increase in the ecosystem's [[primary productivity]] (excessive plant growth and decay), and further effects including lack of oxygen and severe reductions in water quality, fish, and other animal populations. ==Lakes, rivers, and oceans== [[Image:Potomac river eutro.jpg|left|thumb|370px| Though this image has a noticeable cyan tint, the eutrophication of the [[Potomac River]] is evident from its bright green water, caused by a dense bloom of [[cyanobacteria]].]] Eutrophication is frequently a result of nutrient pollution such as the release of sewage effluent and run-off from lawn fertilizers into natural waters (rivers or coasts) although it may also occur naturally in situations where nutrients accumulate (e.g. depositional environments) or where they flow into systems on an ephemeral basis (e.g. intermittent upwelling in coastal systems). Eutrophication generally promotes excessive plant growth and decay, favors certain weedy species over others, and is likely to cause severe reductions in water quality . In aquatic environments, enhanced growth of choking aquatic vegetation or [[phytoplankton]] (that is, an [[algal bloom]]) disrupts normal functioning of the ecosystem, causing a variety of problems such as a lack of [[oxygen]] in the water, needed for fish and [[shellfish]] to survive. The water then becomes cloudy, colored a shade of green, yellow, brown, or red. Human society is impacted as well: eutrophication decreases the resource value of rivers, lakes, and estuaries such that recreation, fishing, hunting, and aesthetic enjoyment are hindered. Health-related problems can occur where eutrophic conditions interfere with drinking [[water treatment]].<ref name="Bartram 1999">Bartram, J., Wayne W. Carmichael, Ingrid Chorus, Gary Jones, and Olav M. Skulberg. 1999. Chapter 1. Introduction, In: ''Toxic Cyanobacteria in Water: A guide to their public health consequences, monitoring and management''. [[World Health Organization]]. URL: [http://www.who.int/water_sanitation_health/resourcesquality/toxicyanbact/en/ WHO document]</ref> Eutrophication was recognized as a [[pollution]] problem in European and North American lakes and reservoirs in the mid-20th century.<ref name="Rohde 1969">Rodhe, W. 1969 Crystallization of eutrophication concepts in North Europe. In: ''Eutrophication, Causes, Consequences, Correctives''. National Academy of Sciences, Washington D.C., Standard Book Number 309-01700-9, 50-64.</ref> Since then, it has become more widespread. Surveys showed that 54% of lakes in [[Asia]] are eutrophic; in [[Europe]], 53%; in [[North America]], 48%; in [[South America]], 41%; and in [[Africa]], 28%.<ref name="ILEC">ILEC/Lake Biwa Research Institute [Eds]. 1988-1993 Survey of the State of the World's Lakes. Volumes I-IV. International Lake Environment Committee, Otsu and United Nations Environment Programme, Nairobi.</ref> Eutrophication can be a natural process in lakes, though many lakes demonstrate the reverse process (becoming less nutrient rich with time), and [[paleolimnology|paleolimnologists]] now recognise that climate change and other external factors are as important, or more important, in regulating the natural productivity of lakes.<ref>Walker, I. R. 2006. Chironomid overview. pp.360-366 in S.A. EIias (ed.) Encyclopedia of Quaternary Science, Vo1. 1, Elsevier, Amsterdam</ref><ref>Whiteside. M. C. 1983. The mythical concept of eutrophication. Hydrobiologia 103, 107-111.</ref> [[estuary|Estuaries]] also tend to be naturally eutrophic because land-derived nutrients are concentrated where run-off enters the marine environment in a confined channel. Eutrophication can also be a natural process in seasonally inundated tropical floodplains such as the [[Barotse Floodplain]] of the [[Zambezi River]]. The first floodwaters to move down the floodplain after the onset of the [[rainy season]], called "red waters", are usually [[Hypoxia (environmental)|hypoxic]] and kill many fish as a result of eutrophication brought on by material picked up by the flood from the plain such as cattle manure, and by the decay of vegetation which grew during the dry season.<ref name="IUCN">[http://www.cbd.int/doc/case-studies/inc/cs-inc-iucn-12-en.pdf "Barotse Floodplain, Zambia: local economic dependence on wetland resources."] ''Case Studies in Wetland Valuation #2'': IUCN, May 2003.</ref> The process may be made worse by the use of fertilisers in crops such as maize, rice and sugarcane grown on the floodplain. Human activities can accelerate the rate at which nutrients enter [[ecosystem]]s. Runoff from [[agriculture]] and development, pollution from [[septic system]]s and [[sewer]]s, and other human-related activities increase the flux of both inorganic nutrients and organic substances into terrestrial, aquatic, and coastal marine ecosystems (including coral reefs). Elevated atmospheric compounds of [[nitrogen]] can increase [[soil]] nitrogen availability. Phosphorus is often regarded as the main culprit in cases of eutrophication in lakes subjected to point source pollution from sewage. The concentration of algae and the trophic state of lakes correspond well to phosphorus levels in water. Studies conducted in the Experimental Lakes Area in Ontario have shown a relationship between the addition of phosphorus and the rate of eutrophication. Humankind has increased the rate of phosphorus cycling on Earth by four times, mainly due to agricultural fertilizer production and application. Between 1950 and 1995, 600,000,000 [[tonne]]s of phosphorus were applied to Earth's surface, primarily on croplands.<ref>Carpenter, S.R., N.F. Caraco, and V.H. Smith. 1998. Nonpoint pollution of surface waters with phosphorus and nitrogen. Ecological Applications 8:559-568.</ref> Control of point sources of phosphorus have resulted in rapid control of eutrophication, mainly due to policy changes. ==Terrestrial ecosystems== Although traditionally thought of as enrichment of aquatic systems by addition of [[fertilizer]]s into [[lake]]s, [[Headlands and bays|bay]]s, or other semi-enclosed waters (even slow-moving [[river]]s), terrestrial ecosystems are subject to similarly adverse impacts.<ref name="APIS 2005">APIS. 2005. Website: [http://www.apis.ac.uk/overview/issues/overview_eutrophication.htm Air Pollution Information System] Eutrophication</ref> Increased content of nitrates in soil frequently leads to undesirable changes in vegetation composition and many plant species are endangered as a result of eutrophication in terrestric ecosystems, e.g. majority of orchid species in Europe. Ecosystems (like some meadows, forests and bogs that are characterized by low nutrient content and species-rich, slowly growing vegetation adapted to lower nutrient levels) are overgrown by faster growing and more competitive species-poor vegetation, like tall grasses, that can take advantage of unnaturally elevated nitrogen level and the area may be changed beyond recognition and vulnerable species may be lost. Eg. species-rich fens are overtaken by reed or reedgrass species, spectacular forest undergrowth affected by run-off from nearby fertilized field is turned into a thick nettle and bramble shrub. Chemical forms of nitrogen are most often of concern with regard to eutrophication because plants have high nitrogen requirements so that additions of nitrogen compounds stimulate plant growth ([[primary production]]). This is also the case with increased levels of phosphorus. Nitrogen is not readily available in soil because N<sub>2</sub>, a gaseous form of nitrogen, is very stable and unavailable directly to higher plants. Terrestrial ecosystems rely on [[microbe|microbial]] [[nitrogen fixation]] to convert N<sub>2</sub> into other physical forms (such as [[nitrate]]s). However, there is a limit to how much nitrogen can be utilized. Ecosystems receiving more nitrogen than the plants require are called '''nitrogen-saturated'''. Saturated terrestrial ecosystems contribute both inorganic and organic nitrogen to freshwater, coastal, and marine eutrophication, where nitrogen is also typically a [[Limiting factor|limiting nutrient]].<ref name="Hornung 1995">Hornung M., Sutton M.A. and Wilson R.B. [Eds.] (1995): Mapping and modelling of critical loads for nitrogen - a workshop report. Grange-over-Sands, Cumbria, UK. UN-ECE Convention on Long Range Transboundary Air Pollution, Working Group for Effects, 24-[[26 October]] [[1994]]. Published by: Institute of Terrestrial Ecology, Edinburgh, UK.</ref> However, because [[phosphorus]] is generally much less [[soluble]] than nitrogen, it is [[leaching|leached]] from the soil at a much slower rate than nitrogen. Consequently, [[phosphorus]] is much more important as a limiting nutrient in aquatic systems.<ref name="Smith 1999">{{cite journal| last=Smith| first= V.H.| coauthors= G.D. Tilman, and J.C. Nekola| year= 1999| title= Eutrophication: impacts of excess nutrient inputs on freshwater, marine, and terrestrial ecosystems| journal=Environmental Pollution| volume=100| pages=179–196| doi= 10.1016/S0269-7491(99)00091-3}}</ref> ==Ecological effects== [[Image:Caspian Sea from orbit.jpg|thumb|200px|Eutrophication is apparent as increased [[turbidity]] in the northern part of the [[Caspian Sea]], imaged from orbit.]] Many ecological effects can arise from stimulating [[primary production]], but there are three particularly troubling ecological impacts: decreased biodiversity, changes in species composition and dominance, and toxicity effects. * Increased biomass of [[phytoplankton]] * Toxic or inedible phytoplankton species * Increases in blooms of gelatinous zooplankton * Decreased biomass of benthic and epiphytic [[algae]] * Changes in macrophyte species composition and biomass * Decreases in water transparency (increased [[turbidity]]) * Color, smell, and water treatment problems * Dissolved oxygen depletion * Increased incidences of fish kills * Loss of desirable fish species * Reductions in harvestable fish and [[shellfish]] * Decreases in perceived aesthetic value of the water body ===Decreased biodiversity=== When an ecosystem experiences an increase in nutrients, primary producers reap the benefits first. In aquatic ecosystems, species such as algae experience a population increase (called an [[algal bloom]]). Algal blooms limit the sunlight available to bottom-dwelling organisms and cause wide swings in the amount of dissolved oxygen in the water. Oxygen is required by all [[Respiration (physiology)|respiring]] plants and animals and it is replenished in daylight by [[photosynthesis|photosynthesizing]] plants and algae. Under eutrophic conditions, dissolved oxygen greatly increases during the day, but is greatly reduced after dark by the respiring algae and by microorganisms that feed on the increasing mass of dead algae. When dissolved oxygen levels decline to [[hypoxia (environmental)|hypoxic]] levels, fish and other marine animals suffocate. As a result, creatures such as fish, shrimp, and especially immobile bottom dwellers die off.<ref name="Horrigan 2002">{{cite journal| last=Horrigan| first= L.| coauthors= R. S. Lawrence, and P. Walker| year= 2002| title= How sustainable agriculture can address the environmental and human health harms of industrial agriculture| journal= Environmental health perspectives| volume=110| pages=445–456}}</ref> In extreme cases, [[Anaerobic organism|anaerobic]] conditions ensue, promoting growth of bacteria such as ''[[Clostridium botulinum]]'' that produces [[toxins]] deadly to birds and mammals. Zones where this occurs are known as [[Dead zone (ecology)|dead zones]]. ===New species invasion=== Eutrophication may cause competitive release by making abundant a normally [[Limiting factor|limiting nutrient]]. This process causes shifts in the species composition of ecosystems. For instance, an increase in nitrogen might allow new, [[invasive species|competitive species]] to invade and out-compete original inhabitant species. This has been shown to occur<ref name="Bertness 2001">Bertness et al. 2001</ref> in [[New England]] [[salt marsh]]es. ===Toxicity=== Some [[algal bloom]]s, otherwise called "nuisance algae" or "harmful algal blooms," are [[toxic]] to plants and animals. Toxic compounds they produce can make their way up the [[food chain]], resulting in animal mortality.<ref name="Anderson 1994">Anderson D.M. 1994. Red tides. Scientific American 271:62-68.</ref> Freshwater algal blooms can pose a threat to livestock. When the algae die or are eaten, [[neurotoxin|neuro]]- and [[hepatotoxins]] are released which can kill animals and may pose a threat to humans.<ref name="Lawton 1991">{{cite journal| last=Lawton| first= L.A.| coauthors= G.A. Codd| year= 1991| title= Cyanobacterial (blue-green algae) toxins and their significance in UK and European waters| journal= Journal of Soil and Water Conservation| volume=40| pages=87–97}}</ref><ref name="Martin 1994">{{cite journal| last=Martin| first= A.| coauthors= G.D. Cooke| year= 1994| title= Health risks in eutrophic water supplies| journal= Lake Line| volume= 14| pages=24–26}}</ref> An example of algal toxins working their way into humans is the case of [[shellfish]] poisoning.<ref name="Shumway 1990">{{cite journal| last= Shumway| first= S.E.| year= 1990| title= A review of the effects of algal blooms on shellfish and aquaculture| journal= Journal of the World Aquaculture Society| volume= 21| pages=65–104| doi= 10.1111/j.1749-7345.1990.tb00529.x}}</ref> Biotoxins created during algal blooms are taken up by shellfish (mussels, oysters), leading to these human foods acquiring the toxicity and poisoning humans. Examples include [[paralysis|paralytic]], neurotoxic, and [[Diarrhea|diarrhoetic]] shellfish poisoning. Other marine animals can be [[Vector (biology)|vectors]] for such toxins, as in the case of [[ciguatera]], where it is typically a predator fish that accumulates the toxin and then poisons humans. Nitrogen can also cause toxic effects directly. When this nutrient is [[Leaching|leached]] into [[groundwater]], drinking water can be affected because concentrations of nitrogen are not filtered out. ‘Blue baby syndrome, or [[methaemoglobinaemia]] is caused when [[nitrate]] (NO<sub>3</sub>) contaminated water is given to human babies. The anaerobic environment in their stomach causes the nitrates to be converted into nitrites (NO<sub>2</sub>). Nitrite binds to [[hemoglobin]] to form [[methemoglobin]], a form that does not carry oxygen. The baby essentially [[Suffocation|suffocates]] as its body receives insufficient oxygen. The problem does not happen in breast fed babies.<ref>{{cite book |last=Walker |first=C. H. |coauthors=S. P. Hopkin, R. M. Sibly and D. B. Peakall |title=Principles of Ecotoxicology |year=1997 |publisher=Taylor & Francis |isbn=0748402209 |pages=7}}</ref> ==Sources of high nutrient runoff== {| border="1" cellpadding="2" align=right |+''Characteristics of point and nonpoint sources of chemical inputs (<ref>Carpenter, S.R., N.F. Caraco, and V.H. Smith. 1998. Nonpoint pollution of surface waters with phosphorus and nitrogen. Ecological Applications 8:559-568.</ref> modified from Novonty and Olem 1994)'' |- |'''Point Sources''' <small> * Wastewater effluent (municipal and industrial) * Runoff and leachate from waste disposal systems * Runoff and infiltration from animal feedlots * Runoff from mines, oil fields, unsewered industrial sites * Overflows of combined storm and sanitary sewers * Runoff from construction sites <20,000 m²</small> <br> '''Nonpoint Sources''' <small> * Runoff from agriculture/irrigation * Runoff from pasture and range * Urban runoff from unsewered areas * Septic tank leachate * Runoff from construction sites >20,000 m² * Runoff from abandoned mines * Atmospheric deposition over a water surface * Other land activities generating contaminants |} In order to gauge how to best prevent eutrophication from occurring, specific sources that contribute to nutrient loading must be identified. There are two common sources of nutrients and organic matter: point and [[Nonpoint source pollution|nonpoint]] sources. ===Point sources=== [[Point source (pollution)|Point source]]s are directly attributable to one influence. In point sources the nutrient waste travels directly from source to water. ===Nonpoint sources=== Nonpoint source pollution (also known as 'diffuse' or 'runoff' pollution) is that which comes from ill-defined and diffuse sources. Nonpoint sources are difficult to regulate and usually vary spatially and temporally (with [[season]], [[Precipitation (meteorology)|precipitation]], and other [[act of god|irregular events]]). It has been shown that nitrogen transport is correlated with various indices of human activity in watersheds,<ref name="Cole 1993">Cole J.J., B.L. Peierls, N.F. Caraco, and M.L. Pace. (1993). Nitrogen loading of rivers as a human-driven process. Pages 141-157 in M.J. McDonnell and S.T.A. Pickett, editors. Humans as components of ecosystems. Springer-Verlag, New York, New York, USA.</ref><ref name="Howarth 1996">Howarth R.W., G. Billen, D. Swaney, A. Townsend, N. Jaworski, K. Lajtha, J.A. Downing, R. Elmgren, N. Caraco, T. Jordan, F. Berendse, J. Freney, V. Kudeyarov, P. Murdoch, and Zhu Zhao-liang. 1996. Regional nitrogen budgets and riverine inputs of N and P for the drainages to the North Atlantic Ocean: natural and human influences. Biogeochemistry 35:75-139.</ref> including the amount of development.<ref name="Bertness 2001"/> [[Agriculture]] and [[urban planning|development]] are activities that contribute most to nutrient loading. There are three reasons that nonpoint sources are especially troublesome:<ref name="Smith 1999"/> =====Soil retention===== Nutrients from human activities tend to accumulate in [[soil]]s and remain there for years. It has been shown<ref name="Sharpley 1996">Sharpley A.N., T.C. Daniel, J.T. Sims, and D.H. Pote. 1996. Determining environmentally sound soil phosphorus levels. Journal of Soil and Water Conservation 51:160-166.</ref> that the amount of [[phosphorus]] lost to surface waters increases linearly with the amount of phosphorus in the soil. Thus much of the nutrient loading in soil eventually makes its way to water. Nitrogen, similarly, has a turnover time of decades or more. =====Runoff to surface water and leaching to groundwater===== Nutrients from human activities tend to travel from land to either surface or ground water. Nitrogen in particular is removed through [[storm drains]], sewage pipes, and other forms of [[surface runoff]]. Nutrient losses in runoff and [[leachate]] are often associated with [[agriculture]]. Modern agriculture often involves the application of nutrients onto fields in order to maximise production. However, farmers frequently apply more nutrients than are taken up by crops<ref name="Buol 1995">Buol S. W. 1995. Sustainability of Soil Use. Annual Review of Ecology and Systematics 26:25-44.</ref> or pastures. Regulations aimed at minimising nutrient exports from agriculture are typically far less stringent than those placed on sewage treatment plants<ref>Carpenter, S.R., N.F. Caraco, and V.H. Smith. 1998. Nonpoint pollution of surface waters with phosphorus and nitrogen. Ecological Applications 8:559-568.</ref> and other point source polluters. =====Atmospheric deposition===== Nitrogen is released into the air because of [[ammonia]] [[volatilization]] and nitrous oxide production. The [[combustion]] of [[fossil fuels]] is a large human-initiated contributor to atmospheric nitrogen pollution. Atmospheric deposition (e.g., in the form of [[acid rain]]) can also effect nutrient concentration in water,<ref name="Paerl 1997">Paerl H. W. 1997. Coastal Eutrophication and Harmful Algal Blooms: Importance of Atmospheric Deposition and Groundwater as "New" Nitrogen and Other Nutrient Sources. Limnology and Oceanography 42:1154-1165.</ref> especially in highly industrialized regions. ===Other causes=== Any factor that causes increased nutrient concentrations can potentially lead to eutrophication. In modeling eutrophication, the rate of water renewal plays a critical role; [[stagnant water]] is allowed to collect more nutrients than bodies with replenished water supplies. It has also been shown that the drying of [[wetlands]] causes an increase in nutrient concentration and subsequent eutrophication booms.<ref name="Mungall 1991">Mungall C. and D.J. McLaren. 1991. Planet under stress: the challenge of global change. Oxford University Press, New York, New York, USA.</ref> ==Prevention and reversal== Eutrophication poses a problem not only to ecosystems, but to humans as well. Reducing eutrophication should be a key concern when considering future policy, and a [[sustainable agriculture|sustainable solution]] for everyone, including farmers and ranchers, seems feasible. While eutrophication does pose problems, humans should be aware that natural runoff (which causes algal blooms in the wild) is common in ecosystems and should thus not reverse nutrient concentrations beyond normal levels. ===Effectiveness=== Cleanup measures have been mostly, but not completely, successful. [[Finland|Finnish]] phosphorus removal measures started in the mid-1970s and have targeted rivers and lakes polluted by industrial and municipal discharges. These efforts have had a 90% removal efficiency.<ref name="Raike 2003">Raimammake A., O.P. Pietilainen, S. Rekolainen, P. Kauppila, H. Pitkanen, J. Niemi, A. Raateland, J. Vuorenmaa. 2003. Trends of phosphorus, nitrogen, and chlorophyll ''a'' concentrations in Finnish rivers and lakes in 1975-2000. The Science of the Total Environment 310:47-59.</ref> Still, some targeted point sources did not show a decrease in runoff despite reduction efforts. ===Minimizing nonpoint pollution: future work=== Nonpoint pollution is the most difficult source of nutrients to manage. The literature suggests, though, that when these sources are controlled, eutrophication decreases. The following steps are recommended to minimize the amount of pollution that can enter aquatic ecosystems from ambiguous sources. =====Riparian buffer zones===== Studies show that intercepting non-point pollution between the source and the water is a successful means of prevention.<ref>Carpenter, S.R., N.F. Caraco, and V.H. Smith. 1998. Nonpoint pollution of surface waters with phosphorus and nitrogen. Ecological Applications 8:559-568.</ref> [[riparian|Riparian buffer zones]] are interfaces between a flowing body of water and land, and have been created near waterways in an attempt to filter pollutants; [[sediment]] and nutrients are deposited here instead of in water. Creating buffer zones near farms and roads is another possible way to prevent nutrients from traveling too far. Still, studies have shown<ref name="Agnold 1997">Angold P. G. 1997. The Impact of a Road Upon Adjacent Heathland Vegetation: Effects on Plant Species Composition. The Journal of Applied Ecology 34:409-417.</ref> that the effects of atmospheric nitrogen pollution can reach far past the buffer zone. This suggests that the most effective means of prevention is from the primary source. =====Prevention policy===== Laws regulating the discharge and treatment of sewage have led to dramatic nutrient reductions to surrounding ecosystems,<ref name="Smith 1999"/> but it is generally agreed that a policy regulating agricultural use of [[fertilizer]] and animal waste must be imposed. In Japan the amount of nitrogen produced by livestock is adequate to serve the fertilizer needs for the agriculture industry.<ref name="Kumazawa 2002">Kumazawa K. 2002. Nitrogen fertilization and nitrate pollution in groundwater in Japan: Present status and measures for sustainable agriculture. Nutrient Cycling in Agroecosystems 63:129-137.</ref> Thus, it is not unreasonable to command livestock owners to clean up animal waste — which when left stagnant will [[Leaching|leach]] into ground water. =====Nitrogen testing and modeling===== Soil Nitrogen Testing (N-Testing) is a technique that helps farmers optimize the amount of fertilizer applied to crops. By testing fields with this method, farmers saw a decrease in fertilizer application costs, a decrease in nitrogen lost to surrounding sources, or both.<ref name="Huang 2001">Huang W. Y., Y. C. Lu, and N. D. Uri. 2001. An assessment of soil nitrogen testing considering the carry-over effect. Applied Mathematical Modelling 25:843-860.</ref> By testing the soil and modeling the bare minimum amount of fertilizer needed, farmers reap economic benefits while the environment remains clean. =====Organic Farming===== Researchers at the [[United States National Academy of Sciences|National Academy of Sciences]] found that that organically fertilizing fields "significantly reduce harmful nitrate leaching" over conventionally fertilized fields.<ref name='PNAS 2006-3-21'> {{cite journal|title=Reduced nitrate leaching and enhanced dentrifier activity and efficiency in organically fertilized soils|journal=Proceedings of the National Academy of Sciences|date=2006-03-21|first=|last=|coauthors=|volume=|issue=|pages=|id= |url=|format=|accessdate=2007-09-30 }}</ref> ===Natural state of algal blooms=== Although the intensity, frequency and extent of algal blooms has tended to increase in response to human activity and human-induced eutrophication, algal blooms are a naturally-occurring phenomenon. The rise and fall of algae populations, as with the population of other living things, is a feature of a healthy ecosystem. Rectification actions aimed at abating eutrophication and algal blooms are usually desirable, but the focus of intervention should not necessarily be aimed at eliminating blooms, but towards creating a sustainable balance that maintains or improves ecosystem health. ==References== {{reflist}} [[Category:Aquatic ecology]] [[Category:Water pollution]] [[Category:Environmental chemistry]] [[Category:Environmental soil science]] [[Category:Limnology]] [[Category:Hydrography]] [[Category:Lakes]] [[Category:Physical geography]] [[Category:Ecology]] [[Category:Fisheries]] [[bg:Еутрофикация]] [[cs:Eutrofizace]] [[da:Eutrofiering]] [[de:Eutrophierung]] [[et:Eutrofikatsioon]] [[el:Ευτροφισμός]] [[es:Eutrofización]] [[eo:Plantoziĝo]] [[fr:Eutrophisation]] [[gl:Eutrofización]] [[id:Eutrofikasi]] [[is:Ofauðgun]] [[it:Eutrofizzazione]] [[he:אאוטריפיקציה]] [[lv:Eitrofikācija]] [[lt:Eutrofikacija]] [[nl:Eutrofiëring]] [[ja:富栄養化]] [[pl:Eutrofizacja]] [[pt:Eutrofização]] [[ru:Эвтрофикация]] [[sr:Цветање воде]] [[fi:Rehevöityminen]] [[sv:Övergödning]] [[uk:Евтрофікація]] [[zh:富营养化]]