Eutrophication: Difference between revisions

'''Eutrophication''' is a general term describing a process in which [[nutrient]]s accumulate in a body of water, resulting in an increased growth of [[microorganism]]s that may deplete the water of [[oxygen]].<ref name="usgs.gov">{{Cite web |title=Nutrients and Eutrophication {{!}} U.S. Geological Survey |url=https://www.usgs.gov/mission-areas/water-resources/science/nutrients-and-eutrophication#:~:text=Eutrophication%20is%20a%20natural%20process,and%20clogging%20water-intake%20pipes. |access-date=February 9, 2024 |website=www.usgs.gov}}</ref><ref>{{Cite journal |title=What Is the Nitrogen Cycle and Why Is It Key to Life? |year=2019 |language=en |doi=10.3389/frym.2019.00041 |doi-access=free |last1=Aczel |first1=Miriam R. |journal=Frontiers for Young Minds |volume=7 |hdl=10044/1/71039 |hdl-access=free }}</ref> ItEutrophication hasmay beenoccur definednaturally or as "degradationa result of waterhuman quality owing to enrichment by nutrients, primarily nitrogen (N) and phosphorus (P) which results in excessive plant (principally algae) growth and decayactions."<ref>{{cite web |last1=Smil |first1=Vaclav |title=Nitrogen Cycle and World Food Production |url=https://vaclavsmil.com/wp-content/uploads/docs/smil-article-worldagriculture.pdf}}</ref> Manmade, or "cultural, eutrophication" isoccurs often a more rapid process in which a variety of polluting inputs including poorly treatedwhen [[sewage]], [[Industrial wastewater treatment|industrial wastewater]], and [[fertilizer runoff]], and other nutrient sources are flowsreleased into the waterenvironment.<ref>{{Cite web |title=Cultural eutrophication {{!}} ecology {{!}} Britannica |url=https://www.britannica.com/science/cultural-eutrophication |access-date=February 9, 2024 |website=www.britannica.com |language=en}}</ref> Such [[nutrient pollution]] usually causes [[algal bloom]]s and bacterial growth, resulting in the depletion of [[dissolved oxygen]] in water and causing substantial [[environmental degradation]].<ref>{{Cite journal |doi=10.1073/pnas.0806112105|pmid=18685114|title=Phosphorus control is critical to mitigating eutrophication|journal=Proceedings of the National Academy of Sciences|volume=105|issue=32|pages=11039–11040|year=2008|last1=Carpenter|first1=S. R.|bibcode=2008PNAS..10511039C|doi-access=free|pmc=2516213}}</ref>

Approaches for prevention and reversal of eutrophication include minimizing [[point source pollution]] from sewage and agriculture as well as other [[Nonpoint source pollution|nonpoint pollution]] sources.<ref name="usgs.gov"/> Additionally, the introducutionintroduction of bacteria and algae-inhibiting organisms such as [[shellfish]] and [[Seaweed farming|seaweed]] can also help reduce nitrogen pollution, which in turn controls the growth of [[cyanobacteria]], the main source of [[Harmful algal bloom|harmful algae blooms]].<ref>{{Cite web |title=Eutrophication and Oyster Aquaculture in the Potomac River Estuary |url=https://coastalscience.noaa.gov/project/eutrophication-oyster-aquaculture-potomac-river/ |access-date=February 9, 2024 |website=NCCOS Coastal Science Website |language=en-US}}</ref>

The term "eutrophication" comes from the [[Greek language|Greek]] ''eutrophos'', meaning "well-nourished".<ref>{{citation |title=eutrophia |date=2016 |url=https://www.thefreedictionary.com/eutrophia |website=American Heritage Dictionary of the English Language |edition=Fifth |publisher=Houghton Mifflin Harcourt Publishing Company |access-date=March 10, 2018 |archive-date=March 11, 2018 |archive-url=https://web.archive.org/web/20180311021548/https://www.thefreedictionary.com/eutrophia |url-status=live }}</ref> Water bodies with very low nutrient levels are termed [[oligotrophic]] and those with moderate nutrient levels are termed [[Trophic state index#Mesotrophic|mesotrophic]]. Advanced eutrophication may also be referred to as [[Dystrophic lake|dystrophic]] and hypertrophic conditions.<ref>{{Cite book|last=Wetzel|first=Robert|title=Limnology|publisher=W.B. Saunders|year=1975|isbn=0-7216-9240-0|location=Philadelphia-London-Toronto|pages=743}}</ref> EutrophicationThus, ineutrophication simplehas words,been isdefined anas algal"degradation bloomof causedwater byquality overpopulationowing ofto enrichment by nutrients which results in theexcessive soil,plant which(principally runalgae) offgrowth intoand waterdecay."<ref>{{cite web |last1=Smil |first1=Vaclav |title=Nitrogen Cycle and World Food Production |url=https://vaclavsmil.com/wp-content/uploads/docs/smil-article-worldagriculture.pdf}}</ref>

Eutrophication is caused by excessive concentrations of nutrients, most commonly [[phosphate|phosphates]] and [[nitrate|nitrates]],<ref name=":6">Schindler, David and Vallentyne, John R. (2004) ''Over fertilization of the World's Freshwaters and Estuaries'', University of Alberta Press, p. 1, {{ISBN|0-88864-484-1}}</ref> although this varies with location. Prior to their being phasing out in the 1970's, phosphate-containing detergents contributed to eutrophication. Since then, sewage and agriculture have emerged as the dominant phosphate sources.<ref name=":11">Werner, Wilfried (2002) "Fertilizers, 6. Environmental Aspects". ''Ullmann's Encyclopedia of Industrial Biology'', Wiley-VCH, Weinheim. {{doi|10.1002/14356007.n10_n05}}</ref> The main sources of nitrogen pollution are from agricultural runoff containing fertilizers and animal wastes, from sewage, and from atmospheric deposition of nitrogen originating from combustion or animal waste.<ref>{{Cite journal|author1-link=David Fowler (physicist)|last1=Fowler|first1=David|last2=Coyle|first2=Mhairi|last3=Skiba|first3=Ute|last4=Sutton|first4=Mark A.|last5=Cape|first5=J. Neil|last6=Reis|first6=Stefan|last7=Sheppard|first7=Lucy J.|last8=Jenkins|first8=Alan|last9=Grizzetti|first9=Bruna|last10=Galloway|first10=James N.|last11=Vitousek|first11=Peter|date=2013|title=The global nitrogen cycle in the twenty-first century|journal=Philosophical Transactions of the Royal Society B: Biological Sciences|volume=368|issue=1621|pages=20130164|doi=10.1098/rstb.2013.0164|pmc=3682748|pmid=23713126}}</ref>

The limitation of productivity in any aquatic system varies with the rate of supply (from external sources) and removal (flushing out) of nutrients from the body of water.<ref>{{Cite journal |last1=Moore |first1=C. M. |last2=Mills |first2=M. M. |last3=Arrigo |first3=K. R. |last4=Berman-Frank |first4=I. |last5=Bopp |first5=L. |last6=Boyd |first6=P. W. |last7=Galbraith |first7=E. D. |last8=Geider |first8=R. J. |last9=Guieu |first9=C. |last10=Jaccard |first10=S. L. |last11=Jickells |first11=T. D. |last12=La Roche |first12=J. |last13=Lenton |first13=T. M. |last14=Mahowald |first14=N. M. |last15=Marañón |first15=E. |date=September 2013 |title=Processes and patterns of oceanic nutrient limitation |url=https://www.nature.com/articles/ngeo1765 |journal=Nature Geoscience |language=en |volume=6 |issue=9 |pages=701–710 |doi=10.1038/ngeo1765 |bibcode=2013NatGe...6..701M |s2cid=249514 |issn=1752-0908}}</ref> This means that some nutrients are more prevalent in certain areas than others and different ecosystems and environments have different limiting factors. Phosphorus is the limiting factor for plant growth in most freshwater ecosystems,<ref>{{Cite journal |last1=Elser |first1=James J. |last2=Bracken |first2=Matthew E.S. |last3=Cleland |first3=Elsa E. |last4=Gruner |first4=Daniel S. |last5=Harpole |first5=W. Stanley |last6=Hillebrand |first6=Helmut |last7=Ngai |first7=Jacqueline T. |last8=Seabloom |first8=Eric W. |last9=Shurin |first9=Jonathan B. |last10=Smith |first10=Jennifer E. |date=July 2007 |title=Global analysis of nitrogen and phosphorus limitation of primary producers in freshwater, marine and terrestrial ecosystems |url=https://onlinelibrary.wiley.com/doi/10.1111/j.1461-0248.2007.01113.x |journal=Ecology Letters |language=en |volume=10 |issue=12 |pages=1135–1142 |doi=10.1111/j.1461-0248.2007.01113.x |pmid=17922835 |bibcode=2007EcolL..10.1135E |hdl=1903/7447 |s2cid=12083235 |issn=1461-023X|hdl-access=free }}</ref> and because phosphate adheres tightly to soil particles and sinks in areas such as wetlands and lakes,<ref>{{Cite web |title=Phosphorus Basics: Understanding Phosphorus Forms and Their Cycling in the Soil |url=https://www.aces.edu/blog/topics/crop-production/understanding-phosphorus-forms-and-their-cycling-in-the-soil/ |access-date=February 10, 2024 |website=Alabama Cooperative Extension System |language=en-US}}</ref> due to its prevalence nowadays more and more phosphorus is accumulating inside freshwater bodies.<ref>{{Cite web |last=US EPA |first=OW |date=November 27, 2013 |title=Indicators: Phosphorus |url=https://www.epa.gov/national-aquatic-resource-surveys/indicators-phosphorus |access-date=February 10, 2024 |website=www.epa.gov |language=en}}</ref><ref name=":18">{{Cite journal |last=Schindler |first=David W. |date=2012 |title=The dilemma of controlling cultural eutrophication of lakes |journal=Proceedings of the Royal Society B: Biological Sciences |volume=279 |issue=1746 |pages=4322–4333 |doi=10.1098/rspb.2012.1032 |pmc=3479793 |pmid=22915669}}</ref> In [[marine ecosystem]]s, nitrogen is the primary limiting nutrient; [[nitrous oxide]] (created by the combustion of [[fossil fuel]]s) and its deposition in the water from the atmosphere has led to an increase in nitrogen levels,<ref>{{Cite web |last=Reay |first=Dave |date=November 9, 2002 |title=Nitrous oxide Sources - Oceans |url=https://www.ghgonline.org/nitrousoceans.htm#:~:text=As%20with%20methane%2C%20man's%20impact,in%20estuaries%20and%20coastal%20waters. |access-date=February 11, 2024 |website=ghgonline |archive-date=December 7, 2023 |archive-url=https://web.archive.org/web/20231207225440/http://ghgonline.org/nitrousoceans.htm#:~:text=As%20with%20methane%2C%20man's%20impact,in%20estuaries%20and%20coastal%20waters. |url-status=dead }}</ref> and also the heightened levels of eutrophication in the ocean.<ref>{{Cite journal |last1=Bristow |first1=L. |last2=Mohr |first2=W. |date=2017 |title=Nutrients that limit growth in the ocean |url=https://doi.org/10.1016/j.cub.2017.03.030 |url-status=live |journal=Current Biology |volume=27 |issue=11 |pages=R431–R510 |doi=10.1016/j.cub.2017.03.030 |pmid=28586682 |bibcode=2017CBio...27.R474B |s2cid=21052483 |archive-url=https://web.archive.org/web/20220928180557/https://www.cell.com/current-biology/fulltext/S0960-9822(17)30328-7?_returnURL=https%3A%2F%2Ffly.jiuhuashan.beauty%3A443%2Fhttps%2Flinkinghub.elsevier.com%2Fretrieve%2Fpii%2FS0960982217303287%3Fshowall%3Dtrue |archive-date=September 28, 2022 |access-date=June 17, 2021 |hdl-access=free |hdl=21.11116/0000-0001-C1AA-5}}</ref>

=== '''Minimizing pollution from sewage''' ===

# Planting Field Buffers - By planting trees, shrubs and grasses along the edges of fields to help catch the runoff and absorb some nutrients before the water makes it to a nearby water body.<ref name="Carpenter, S.R. 1998">{{cite journal|last1=Carpenter|first1=S. R.|last2=Caraco|first2=N. F.|last3=Correll|first3=D. L.|last4=Howarth|first4=R. W.|last5=Sharpley|first5=A. N.|last6=Smith|first6=V. H.|date=August 1998|title=Nonpoint Pollution of Surface Waters with Phosphorus and Nitrogen|journal=Ecological Applications|volume=8|issue=3|pages=559|doi=10.2307/2641247|jstor=2641247|hdl-access=free|hdl=1813/60811}}</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">{{cite journal|author=Angold P. G. |year=1997|title= The Impact of a Road Upon Adjacent Heathland Vegetation: Effects on Plant Species Composition|journal= The Journal of Applied Ecology |volume=34|pages=409–417|jstor=2404886|doi=10.2307/2404886|issue=2|bibcode=1997JApEc..34..409A }}</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.

Reducing nutrient  inputs is a keycrucial precondition for restoration. Still, but there are two caveats: Firstly, it can take a long time, particularlymainly because of the storage of nutrients in [[sediment]]s. Secondly, restoration may need more than a simple reversal of inputs since there are sometimes several stable but very different ecological states.<ref>{{Cite journal|last1=May|first1=L|last2=Olszewska|first2=J|last3=Gunn|first3=I D M|last4=Meis|first4=S|last5=Spears|first5=B M|date=2020|title=Eutrophication and restoration in temperate lakes|journal=IOP Conference Series: Earth and Environmental Science|volume=535|issue=1|pages=012001|doi=10.1088/1755-1315/535/1/012001|bibcode=2020E&ES..535a2001M|s2cid=225481650|issn=1755-1307|doi-access=free}}</ref> Recovery of eutrophicated lakes is slow, often requiring several decades.<ref name=":18" />

In [[environmental remediation]], nutrient removal technologies include [[biofiltration]], which uses living material to capture and biologically degrade pollutants. Examples include green belts, [[riparian]] areas, natural and constructed wetlands, and treatment ponds.

Nutrient bioextraction is bioremediation involving cultured plants and animals. Nutrient bioextraction or bioharvesting is the practice of farming and harvesting [[shellfish]] and [[seaweed]] forto the purpose of removingremove nitrogen and other nutrients from natural water bodies.<ref>{{cite web|title=Nutrient Bioextraction Overview|url=http://longislandsoundstudy.net/issues-actions/water-quality/nutrient-bioextraction-overview/|access-date=March 22, 2018|publisher=Long Island Sound Study partnership|location=Stamford, CT|archive-date=October 6, 2017|archive-url=https://web.archive.org/web/20171006062352/http://longislandsoundstudy.net/issues-actions/water-quality/nutrient-bioextraction-overview/|url-status=live}}</ref>

{{See also|Nutrient pollution}}[[File:Mussels at Strawberry Rocks PC013145.JPG|thumb|Mussels are an example of organisms that act as nutrient biextractors. They consume the nitrogen in water, depleting algae of their nutrients.|231x231px]]

{{See also|Nutrient pollution}}It has been suggested that nitrogen removal by oyster reefs could generate net benefits for sources facing nitrogen emission restrictions, similar to other nutrient trading scenarios. Specifically, if oysters maintain nitrogen levels in estuaries below thresholds, thatthen wouldoysters leadeffectively tostave theoff impositionan ofenforcement emissionresponse limits,and oysterscompliance effectivelycosts saveparties theresponsible sourcesfor thenitrogen complianceemission costs theywould otherwise would incur.<ref>{{cite web|last=Kroeger|first=Timm|year=2012|title=Dollars and Sense: Economic Benefits and Impacts from two Oyster Reef Restoration Projects in the Northern Gulf of Mexico|url=http://www.nature.org/ourinitiatives/regions/northamerica/oyster-restoration-study-kroeger.pdf|url-status=dead|archive-url=https://web.archive.org/web/20160304002313/http://www.nature.org/ourinitiatives/regions/northamerica/oyster-restoration-study-kroeger.pdf|archive-date=March 4, 2016|access-date=May 29, 2013|publisher=The Nature Conservancy}}</ref> Several studies have shown that oysters and mussels have the capacity tocan dramatically impact nitrogen levels in estuaries.<ref>{{cite book| vauthors = Newell RI, Fisher TR, Holyoke RR, Cornwell JC |title=The Comparative Roles of Suspension Feeders in Ecosystems | volume = 47 |publisher=Springer|year=2005| veditors = Dame R, Olenin S |edition=NATO Science Series IV: Earth and Environmental Sciences|location=Netherlands|pages=93–120|contribution=Influence of eastern oysters on nitrogen and phosphorus regeneration in Chesapeake Bay, USA}}</ref><ref>{{cite book| vauthors = Grabowski JH, Petersen CM |title=Restoring oyster reefs to recover ecosystem services|publisher=Elsevier-Academic Press|year=2007| veditors = Cuddington K, Byers JE, Wilson WG, Hastings A |edition=Ecosystem Engineers: Concepts, Theory and Applications|location=Amsterdam|pages=281–298}}</ref><ref>{{cite web|year=2010|title=International Workshop on Bioextractive Technologies for Nutrient Remediation Summary Report|url=http://www.nefsc.noaa.gov/nefsc/publications/|publisher=US Dept Commerce, Northeast Fish Sci Cent Ref Doc. 10-19; 12 p. Available from: National Marine Fisheries Service, 166 Water Street, Woods Hole, MA 02543-1026|vauthors=Rose JM, Tedesco M, Wikfors GH, Yarish C|access-date=February 15, 2022|archive-date=October 29, 2019|archive-url=https://web.archive.org/web/20191029030853/https://www.nefsc.noaa.gov/nefsc/publications/|url-status=live}}</ref> Filter feeding activity is considered beneficial to water quality<ref>Burkholder, JoAnn M. and Sandra E. Shumway. (2011) "Bivalve shellfish aquaculture and eutrophication", in ''Shellfish Aquaculture and the Environment''. Ed. Sandra E. Shumway. John Wiley & Sons, {{ISBN|0-8138-1413-8}}.</ref> by controlling phytoplankton density and sequestering nutrients, which can be removed from the system through shellfish harvest, buried in the sediments, or lost through [[denitrification]].<ref>{{Cite journal|last1=Kaspar|first1=H. F.|last2=Gillespie|first2=P. A.|last3=Boyer|first3=I. C.|last4=MacKenzie|first4=A. L.|year=1985|title=Effects of mussel aquaculture on the nitrogen cycle and benthic communities in Kenepuru Sound, Marlborough Sounds, New Zealand|journal=Marine Biology|volume=85|issue=2|pages=127–136|doi=10.1007/BF00397431|bibcode=1985MarBi..85..127K |s2cid=83551118}}</ref><ref>{{Cite journal|last1=Newell|first1=R. I. E.|last2=Cornwell|first2=J. C.|last3=Owens|first3=M. S.|year=2002|title=Influence of simulated bivalve biodeposition and microphytobenthos on sediment nitrogen dynamics: A laboratory study|journal=Limnology and Oceanography|volume=47|issue=5|pages=1367–1379|bibcode=2002LimOc..47.1367N|doi=10.4319/lo.2002.47.5.1367|doi-access=free}}</ref> Foundational work toward the idea of improving marine water quality through shellfish cultivation was conducted by Odd Lindahl et al., using [[mussels]] in Sweden.<ref>{{Cite journal|last1=Lindahl|first1=O.|last2=Hart|first2=R.|last3=Hernroth|first3=B.|last4=Kollberg|first4=S.|last5=Loo|first5=L. O.|last6=Olrog|first6=L.|last7=Rehnstam-Holm|first7=A. S.|last8=Svensson|first8=J.|last9=Svensson|first9=S.|last10=Syversen|first10=U.|year=2005|title=Improving marine water quality by mussel farming: A profitable solution for Swedish society|url=http://www.aquacircle.org/images/pdfdokumenter/efterret07/ambi3402_131-138.pdf|journal=Ambio|volume=34|issue=2|pages=131–138|citeseerx=10.1.1.589.3995|doi=10.1579/0044-7447-34.2.131|pmid=15865310|bibcode=2005Ambio..34..131L |s2cid=25371433|access-date=November 1, 2017|archive-date=September 22, 2017|archive-url=https://web.archive.org/web/20170922011833/http://www.aquacircle.org/images/pdfdokumenter/efterret07/ambi3402_131-138.pdf|url-status=live}}</ref> In the United States, shellfish restoration projects have been conducted on the East, West and Gulf coasts.<ref>Brumbaugh, R.D. et al. (2006). [http://www.conservationgateway.org/Files/Pages/practitioner%E2%80%99s-guide-desi.aspx A Practitioners Guide to the Design and Monitoring of Shellfish Restoration Projects: An Ecosystem Services Approach] {{Webarchive|url=https://web.archive.org/web/20130701024305/http://www.conservationgateway.org/Files/Pages/practitioner%E2%80%99s-guide-desi.aspx |date=July 1, 2013 }}. The Nature Conservancy, Arlington, VA.</ref> See [[nutrient pollution]] for an extended explanation of [[Nutrient pollution#Nutrient remediation|nutrient remediation]] using shellfish.

Studies have demonstrated seaweed's potential to improve nitrogen levels.<ref>{{Cite journal |last1=Kim |first1=Jang K. |last2=Kraemer |first2=George P. |last3=Yarish |first3=Charles |date=2014 |title=Field scale evaluation of seaweed aquaculture as a nutrient bioextraction strategy in Long Island Sound and the Bronx River Estuary |journal=Aquaculture |volume=433 |pages=148–156 |bibcode=2014Aquac.433..148K |doi=10.1016/j.aquaculture.2014.05.034}}</ref><ref>{{cite web |last1=Kroeger |first1=Timm |date=May 2012 |title=Dollars and Sense: Economic Benefits and Impacts from two Oyster Reef Restoration Projects in the Northern Gulf of Mexico |url=https://www.conservationgateway.org/Files/Pages/dollars-and-sense-economi.aspx |url-status=live |archive-url=https://web.archive.org/web/20200803151420/http://www.conservationgateway.org/Files/Pages/dollars-and-sense-economi.aspx |archive-date=August 3, 2020 |access-date=July 29, 2020 |website=The Nature Conservancy}}</ref> [[Seaweed farming|Seaweed aquaculture]] offers an opportunity to mitigate, and adapt to climate change.<ref>{{cite journal|last1=Duarte|first1=Carlos M.|last2=Wu|first2=Jiaping|last3=Xiao|first3=Xi|last4=Bruhn|first4=Annette|last5=Krause-Jensen|first5=Dorte|date=April 12, 2017|title=Can Seaweed Farming Play a Role in Climate Change Mitigation and Adaptation?|journal=Frontiers in Marine Science|volume=4|doi=10.3389/fmars.2017.00100|doi-access=free|hdl=10754/623247|hdl-access=free}}</ref> Seaweed, such as kelp, also absorbs phosphorus and nitrogen<ref>{{Cite web|url=https://e360.yale.edu/features/new_breed_of_ocean_farmer_aims_to_revive_global_seas|title=Can We Save the Oceans By Farming Them?|website=Yale E360|access-date=March 8, 2019|archive-date=October 19, 2019|archive-url=https://web.archive.org/web/20191019150923/https://e360.yale.edu/features/new_breed_of_ocean_farmer_aims_to_revive_global_seas|url-status=live}}</ref> and is thus usefulhelpful to remove excessive nutrients from polluted parts of the sea.<ref>{{Cite journal|last1=Xiao|first1=X.|last2=Agusti|first2=S.|last3=Lin|first3=F.|last4=Li|first4=K.|last5=Pan|first5=Y.|last6=Yu|first6=Y.|last7=Zheng|first7=Y.|last8=Wu|first8=J.|last9=Duarte|first9=C. M.|year=2017|title=Nutrient removal from Chinese coastal waters by large-scale seaweed aquaculture|journal=Scientific Reports|volume=7|pages=46613|bibcode=2017NatSR...746613X|doi=10.1038/srep46613|pmc=5399451|pmid=28429792}}</ref> Some cultivated seaweeds have very high productivity and could absorb large quantities of N, P, {{CO2}}, producing large amounts of {{chem2|O2}} having an excellent effect on decreasing eutrophication.<ref>{{Citation|last=Duarte|first=Carlos M.|title=Coastal eutrophication research: A new awareness |date=2009|work=Eutrophication in Coastal Ecosystems|pages=263–269|publisher=Springer Netherlands|doi=10.1007/978-90-481-3385-7_22|isbn=978-90-481-3384-0}}</ref> It is believed that seaweed cultivation in large scale should be a good solution to the eutrophication problem in [[coastal waters]].

One obviousAnother technique for combatting [[Hypoxia (environmental)|hypoxia]]/eutrophication in localized situations is direct injection of compressed air, asa illustratedtechnique byused in the restoration of the [[Salford Docks]] area of the [[Manchester Ship Canal]] in England.<ref>{{cite web|url= http://www.mangeogsoc.org.uk/egm/5_1.pdf|access-date=December 11, 2007|date=August 21, 2003|title= Exploring Greater Manchester&nbsp;– a fieldwork guide: The fluvioglacial gravel ridges of Salford and flooding on the River Irwell|author= Hindle, P.|publisher=Manchester Geographical Society}} p. 13</ref> For smaller-scale waters such as aquaculture ponds, pump aeration is standard.<ref>{{cite web | url=https://thefishsite.com/articles/pond-aeration | title=Pond Aeration | date=April 10, 2006 }}</ref>

The removal ofRemoving [[phosphorus cycle|phosphorus]] can in principle remediate eutrophication.<ref>{{Cite journal|doi=10.1021/es5036267|pmid=25137490|title=Geo-Engineering in Lakes: A Crisis of Confidence?|journal=Environmental Science & Technology|volume=48|issue=17|pages=9977–9979|year=2014|last1=Spears|first1=Bryan M.|last2=Maberly|first2=Stephen C.|last3=Pan|first3=Gang|last4=MacKay|first4=Ellie|last5=Bruere|first5=Andy|last6=Corker|first6=Nicholas|last7=Douglas|first7=Grant|last8=Egemose|first8=Sara|last9=Hamilton|first9=David|last10=Hatton-Ellis|first10=Tristan|last11=Huser|first11=Brian|last12=Li|first12=Wei|last13=Meis|first13=Sebastian|last14=Moss|first14=Brian|last15=Lürling|first15=Miquel|last16=Phillips|first16=Geoff|last17=Yasseri|first17=Said|last18=Reitzel|first18=Kasper|bibcode=2014EnST...48.9977S|url=http://ir.rcees.ac.cn/handle/311016/9551|access-date=September 8, 2020|archive-date=October 21, 2021|archive-url=https://web.archive.org/web/20211021121418/http://ir.rcees.ac.cn/handle/311016/9551|url-status=live}}</ref><ref>{{Cite journal |doi=10.5268/IW-4.4.769|title=Geoengineering in lakes: Welcome attraction or fatal distraction?|journal=Inland Waters|volume=4|issue=4|pages=349–356|year=2014|last1=MacKay|first1=Eleanor|last2=Maberly|first2=Stephen|last3=Pan|first3=Gang|last4=Reitzel|first4=Kasper|last5=Bruere|first5=Andy|last6=Corker|first6=Nicholas|last7=Douglas|first7=Grant|last8=Egemose|first8=Sara|last9=Hamilton|first9=David|last10=Hatton-Ellis|first10=Tristan|last11=Huser|first11=Brian|last12=Li|first12=Wei|last13=Meis|first13=Sebastian|last14=Moss|first14=Brian|last15=Lürling|first15=Miquel|last16=Phillips|first16=Geoff|last17=Yasseri|first17=Said|last18=Spears|first18=Bryan|bibcode=2014InWat...4..349M |hdl=10072/337267|s2cid=55610343|hdl-access=free}}</ref> Of the several phosphate sorbents, [[alum]] ([[aluminium sulfate]]) is of practical interest.<ref>{{cite web|url=http://www.dnr.state.wi.us/org/water/fhp/papers/alum_brochure.pdf |title=Wisconsin Department of Natural Resources |access-date=August 3, 2010 |url-status=dead |archive-url=https://web.archive.org/web/20091128030217/http://www.dnr.state.wi.us/org/water/fhp/papers/alum_brochure.pdf |archive-date=November 28, 2009 }}</ref>) Many materials have been investigated.<ref>{{Cite journal|doi=10.1007/s10452-016-9575-2|title=Guiding principles for the development and application of solid-phase phosphorus adsorbents for freshwater ecosystems|journal=Aquatic Ecology|volume=50|issue=3|pages=385–405|year=2016|last1=Douglas|first1=G. B.|last2=Hamilton|first2=D. P.|last3=Robb|first3=M. S.|last4=Pan|first4=G.|last5=Spears|first5=B. M.|last6=Lurling|first6=M.|bibcode=2016AqEco..50..385D |hdl=10072/406333 |s2cid=18154662|url=http://irep.ntu.ac.uk/id/eprint/27767/1/PubSub5337_Pan.pdf|access-date=December 15, 2019|archive-date=September 19, 2020|archive-url=https://web.archive.org/web/20200919184710/http://irep.ntu.ac.uk/id/eprint/27767/1/PubSub5337_Pan.pdf|url-status=live}}</ref><ref>{{Cite journal|doi=10.1016/J.WATRES.2016.03.035|pmid=27039034|title=Editorial – A critical perspective on geo-engineering for eutrophication management in lakes|journal=Water Research|volume=97|pages=1–10|year=2016|last1=Lürling|first1=Miquel|last2=MacKay|first2=Eleanor|last3=Reitzel|first3=Kasper|last4=Spears|first4=Bryan M.|bibcode=2016WatRe..97....1L |url=http://nora.nerc.ac.uk/id/eprint/513724/1/N513724PP.pdf|access-date=December 15, 2019|archive-date=July 31, 2020|archive-url=https://web.archive.org/web/20200731023813/http://nora.nerc.ac.uk/id/eprint/513724/1/N513724PP.pdf|url-status=live}}</ref> The phosphate sorbent is commonly applied in the surface of the water body and it sinks to the bottom of the lake reducing phosphate, such sorbents have been applied worldwide to manage eutrophication and algal bloom (for example under the commercial name [[Phoslock]]).<ref>{{Cite journal |doi=10.1016/j.watres.2015.06.051|pmid=26250754|title=Longevity and effectiveness of aluminum addition to reduce sediment phosphorus release and restore lake water quality|journal=Water Research|volume=97|pages=122–132|year=2016|last1=Huser|first1=Brian J.|last2=Egemose|first2=Sara|last3=Harper|first3=Harvey|last4=Hupfer|first4=Michael|last5=Jensen|first5=Henning|last6=Pilgrim|first6=Keith M.|last7=Reitzel|first7=Kasper|last8=Rydin|first8=Emil|last9=Futter|first9=Martyn|bibcode=2016WatRe..97..122H |doi-access=free}}</ref><ref>{{Cite journal |doi=10.1016/j.watres.2013.08.019|pmid=24041525|title=Controlling eutrophication by combined bloom precipitation and sediment phosphorus inactivation|journal=Water Research|volume=47|issue=17|pages=6527–6537|year=2013|last1=Lürling|first1=Miquel|last2=Oosterhout|first2=Frank van|bibcode=2013WatRe..47.6527L }}</ref><ref>{{Cite journal |doi=10.1080/10402381.2016.1265618|title=Attempted management of cyanobacteria by Phoslock (Lanthanum-modified clay) in Canadian lakes: Water quality results and predictions|journal=Lake and Reservoir Management|volume=33|issue=2|pages=163–170|year=2017|last1=Nürnberg|first1=Gertrud K.|bibcode=2017LRMan..33..163N |s2cid=89762486}}</ref><ref>{{Cite journal |doi=10.1080/10402381.2016.1263693|title=Nine years of phosphorus management with lanthanum modified bentonite (Phoslock) in a eutrophic, shallow swimming lake in Germany|journal=Lake and Reservoir Management|volume=33|issue=2|pages=119–129|year=2017|last1=Epe|first1=Tim Sebastian|last2=Finsterle|first2=Karin|last3=Yasseri|first3=Said|bibcode=2017LRMan..33..119E |s2cid=90314146}}</ref><ref name=":110">{{Cite journal |last1=Kennedy |first1=Robert H. |last2=Cook |first2=G. Dennis |title=Control of Lake Phosphorus with Aluminum Sulfate: Dose Determination and Application Techniques |date=June 1982 |url=https://doi.org/10.1111/j.1752-1688.1982.tb00005.x |journal=Journal of the American Water Resources Association |volume=18 |issue=3 |pages=389–395 |doi=10.1111/j.1752-1688.1982.tb00005.x |bibcode=1982JAWRA..18..389K |issn=1093-474X}}</ref> In a large -scale study, 114 lakes were monitored for the effectiveness of alum at phosphorus reduction. Across all lakes, alum effectively reduced the phosphorus for 11 years. While there was variety in the longevity (21 years in deep lakes and 5.7 years in shallow lakes), the results express the effectiveness of alum at controlling phosphorus within lakes.<ref>{{Cite book |last1=Huser |first1=Brian J. |last2=Egemose |first2=Sara |last3=Harper |first3=Harvey |last4=Hupfer |first4=Michael |last5=Jensen |first5=Henning |last6=Pilgrim |first6=Keith M. |last7=Reitzel |first7=Kasper |last8=Rydin |first8=Emil |last9=Futter |first9=Martyn |date=2016 |title=Longevity and effectiveness of aluminum addition to reduce sediment phosphorus release and restore lake water quality |location=[[Fjärdingen]] |publisher=Uppsala universitet, Limnologi Uppsala universitet |oclc=1233676585 }}</ref> Alum treatment is less effective in deep lakes, as well as lakes with substantial external phosphorus loading.<ref name=":22">Cooke, G. D., Welch, E. B., Martin, A. B., Fulmer, D. G., Hyde, J. B., & Schrieve, G. D. (1993). Effectiveness of Al, Ca, and Fe salts for control of internal phosphorus loading in shallow and deep lakes. ''Hydrobiologia'', ''253''(1), 323-335.</ref>

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