phosphorus cycle

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Phosphorus is an essential nutrient for plants and animals. Phosphorus is a limiting nutrient for aquatic organisms. Phosphorus forms parts of important life-sustaining molecules that are very common in the biosphere. Phosphorus does enter the atmosphere in very small amounts when dust containing phosphorus is dissolved in rainwater and sea spray, but the element mainly remains on land and in rock and soil minerals. Phosphates which are found in fertilizers, sewage and detergents, can cause pollution in lakes and streams. Over-enrichment of phosphate in both fresh and inshore marine waters can lead to massive algae blooms. In fresh water, the death and decay of these blooms leads to eutrophication. An example of this is the Canadian Experimental Lakes Area.

Freshwater algal blooms are generally caused by excess phosphorus, while those that take place in saltwater tend to occur when excess nitrogen is added.{{cite web |title=Eutrophication |website=www.soils.org |publisher=Soil Science Society of America |url=https://www.soils.org/discover-soils/soils-in-the-city/green-infrastructure/important-terms/eutrophication |access-date=2014-04-14 |url-status=dead |archive-url=https://web.archive.org/web/20140416123353/https://www.soils.org/discover-soils/soils-in-the-city/green-infrastructure/important-terms/eutrophication |archive-date=2014-04-16}} However, it is possible for eutrophication to be due to a spike in phosphorus content in both freshwater and saltwater environments.{{Cite journal |last1=Rabalais |first1=Nancy N. |last2=Turner |first2=R. Eugene |last3=Wiseman |first3=William J. |date=November 2002 |title=Gulf of Mexico Hypoxia, A.K.A. "The Dead Zone" |url=https://www.annualreviews.org/doi/10.1146/annurev.ecolsys.33.010802.150513 |journal=Annual Review of Ecology and Systematics |language=en |volume=33 |issue=1 |pages=235–263 |doi=10.1146/annurev.ecolsys.33.010802.150513 |bibcode=2002AnRES..33..235R |issn=0066-4162|url-access=subscription }}{{Cite web |title=Eutrophication |url=https://www.bsag.fi/en/the-baltic-sea/eutrophication/ |access-date=2024-04-14 |website=Baltic Sea Action Group |language=en-GB}}

Phosphorus occurs most abundantly in nature as part of the orthophosphate ion (PO₄)³⁻, consisting of a P atom and 4 oxygen atoms. On land most phosphorus is found in rocks and minerals. Phosphorus-rich deposits have generally formed in the ocean or from guano, and over time, geologic processes bring ocean sediments to land. Weathering of rocks and minerals release phosphorus in a soluble form where it is taken up by plants, and it is transformed into organic compounds. The plants may then be consumed by herbivores and the phosphorus is either incorporated into their tissues or excreted. After death, the animal or plant decays, and phosphorus is returned to the soil where a large part of the phosphorus is transformed into insoluble compounds. Runoff may carry a small part of the phosphorus back to the ocean. Generally with time (thousands of years) soils become deficient in phosphorus leading to ecosystem retrogression.{{cite journal |author1=Peltzer, D.A. |author2=Wardle, D.A. |author3=Allison, V.J. |author4=Baisden, W.T. |author5=Bardgett, R.D. |author6=Chadwick, O.A. |author7=Condron, L.M. |author8=Parfitt, R.L. |author9=Porder, S. |author10=Richardson, S.J. |author11=Turner, B.L. |title=Understanding ecosystem retrogression |journal=Ecological Monographs |date=November 2010 |volume=80 |issue=4 |pages=509–529 |doi=10.1890/09-1552.1|bibcode=2010EcoM...80..509P }}

There are four major pools of phosphorus in freshwater ecosystems: dissolved inorganic phosphorus (DIP), dissolved organic phosphorus (DOP), particulate inorganic phosphorus (PIP) and particulate organic phosphorus (POP). Dissolved material is defined as substances that pass through a 0.45 μm filter.{{cite book |last=Wetzel |first=R.G. |year=2001 |title=Limnology: Lake and river ecosystems |place=San Diego, CA |publisher=Academic Press}} DIP consists mainly of orthophosphate ({{chem2|PO4(3-)}}) and polyphosphate, while DOP consists of DNA and phosphoproteins. Particulate matter are the substances that get caught on a 0.45 μm filter and do not pass through. POP consists of both living and dead organisms, while PIP mainly consists of hydroxyapatite, Ca₅(PO₄)₃OH . Inorganic phosphorus comes in the form of readily soluble orthophosphate. Particulate organic phosphorus occurs in suspension in living and dead protoplasm and is insoluble. Dissolved organic phosphorus is derived from the particulate organic phosphorus by excretion and decomposition and is soluble.

The primary biological importance of phosphates is as a component of nucleotides, which

serve as energy storage within cells (ATP) or when linked together, form the nucleic acids DNA and RNA. The double helix of our DNA is only possible because of the phosphate ester bridge that binds the helix. Besides making biomolecules, phosphorus is also found in bone and the enamel of mammalian teeth, whose strength is derived from calcium phosphate in the form of hydroxyapatite. It is also found in the exoskeleton of insects, and phospholipids (found in all biological membranes).{{cite web |title=Phosphorus Cycle |publisher=The Environmental Literacy Council |website=enviroliteracy.org |url=http://www.enviroliteracy.org/article.php/480.html |url-status=live |archive-url=https://web.archive.org/web/20061108121612/http://www.enviroliteracy.org/article.php/480.html |archive-date=2006-11-08}} It also functions as a buffering agent in maintaining acid base homeostasis in the human body.{{cite book |last1=Voet |first1=D. |last2=Voet |first2=J.G. |year=2003 |title=Biochemistry |pages=607–608}}

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Phosphates move quickly through plants and animals; however, the processes that move them through the soil or ocean are very slow, making the phosphorus cycle overall one of the slowest biogeochemical cycles.{{cite book |last=Schlesinger |first=W.H. |title=Biogeochemistry: An analysis of global change |year=1991}}{{cite journal |author1=Oelkers, E.H. |author2=Valsami-Jones, E. |author3=Roncal-Herrero, T. |title=Phosphate mineral reactivity: From global cycles to sustainable development |journal=Mineralogical Magazine |date=February 2008 |volume=72 |issue=1 |pages=337–40 |doi=10.1180/minmag.2008.072.1.337 |bibcode=2008MinM...72..337O |s2cid=97795738 }}

The global phosphorus cycle includes four major processes:

:(i) tectonic uplift and exposure of phosphorus-bearing rocks such as apatite to surface weathering;{{cite journal |last1=Buendía |first1=C. |last2=Kleidon |first2=A. |last3=Porporato |first3=A. |date=2010-06-25 |title=The role of tectonic uplift, climate, and vegetation in the long-term terrestrial phosphorous [sic] cycle |journal=Biogeosciences |volume=7 |issue=6 |pages=2025–2038 |doi=10.5194/bg-7-2025-2010 |bibcode=2010BGeo....7.2025B |doi-access=free |issn=1726-4170 |language=English |url=https://bg.copernicus.org/articles/7/2025/2010/|hdl=11858/00-001M-0000-000E-D96B-A |hdl-access=free }}

:(ii) physical erosion, and chemical and biological weathering of phosphorus-bearing rocks to provide dissolved and particulate phosphorus to soils,{{cite journal |last1=Adediran |first1=Gbotemi A. |last2=Tuyishime |first2=J.R. Marius |last3=Vantelon |first3=Delphine |last4=Klysubun |first4=Wantana |last5=Gustafsson |first5=Jon Petter |date=October 2020 |title=Phosphorus in 2D: Spatially resolved P speciation in two Swedish forest soils as influenced by apatite weathering and podzolization |journal=Geoderma |volume=376 |pages=114550 |doi=10.1016/j.geoderma.2020.114550 |bibcode=2020Geode.376k4550A |doi-access=free |language=en |issn=0016-7061}} lakes and rivers;

:(iii) riverine and subsurface transportation of phosphorus to various lakes and run-off to the ocean;

:(iv) sedimentation of particulate phosphorus (e.g., phosphorus associated with organic matter and oxide/carbonate minerals) and eventually burial in marine sediments (this process can also occur in lakes and rivers).{{cite book |author=Ruttenberg, K.C. |chapter=The global phosphorus cycle |title=Treatise on Geochemistry |date=2014 |pages=499–558 |publisher=Elsevier |doi=10.1016/b978-0-08-095975-7.00813-5 |isbn=978-0-08-098300-4}}

In terrestrial systems, bioavailable P (‘reactive P’) mainly comes from weathering of phosphorus-containing rocks. The most abundant primary phosphorus-mineral in the crust is apatite, which can be dissolved by natural acids generated by soil microbes and fungi, or by other chemical weathering reactions and physical erosion.{{cite book |author=Slomp, C.P. |chapter=Phosphorus cycling in the estuarine and coastal zones |title=Treatise on Estuarine and Coastal Science |volume=5 |date=2011 |pages=201–229 |publisher=Elsevier |doi=10.1016/b978-0-12-374711-2.00506-4 |isbn=978-0-08-087885-0}} The dissolved phosphorus is bioavailable to terrestrial organisms and plants and is returned to the soil after their decay. Phosphorus retention by soil minerals (e.g., adsorption onto iron and aluminum oxyhydroxides in acidic soils and precipitation onto calcite in neutral-to-calcareous soils) is usually viewed as the most important process in controlling terrestrial P-bioavailability in the mineral soil.{{cite journal |author1=Arai, Y. |author2=Sparks, D.L. |title=Phosphate reaction dynamics in soils and soil components: A multiscale approach |date=2007 |journal=Advances in Agronomy |volume=94 |pages=135–179 |publisher=Elsevier |doi=10.1016/s0065-2113(06)94003-6 |isbn=978-0-12-374107-3}} This process can lead to the low level of dissolved phosphorus concentrations in soil solution. Various physiological strategies are used by plants and microorganisms for obtaining phosphorus from this low level of phosphorus concentration.{{cite journal |author1=Shen, J. |author2=Yuan, L. |author3=Zhang, J. |author4=Li, H. |author5=Bai, Z. |author6=Chen, X. |author7=Zhang, W. |author8=Zhang, F |date=July 2011 |title=Phosphorus dynamics: From soil to plant |journal=Plant Physiology |volume=156 |issue=3 |pages=997–1005 |pmid=21571668 |pmc=3135930 |doi=10.1104/pp.111.175232}}

Soil phosphorus is usually transported to rivers and lakes and can then either be buried in lake sediments or transported to the ocean via river runoff. Atmospheric phosphorus deposition is another important marine phosphorus source to the ocean.{{cite journal |author1=Paytan, A. |author2=McLaughlin, K. |title=The oceanic phosphorus cycle |journal=Chemical Reviews |volume=107 |issue=2 |pages=563–576 |date=February 2007 |pmid=17256993 |doi=10.1021/cr0503613|s2cid=1872341 }} In surface seawater, dissolved inorganic phosphorus, mainly orthophosphate ({{chem2|PO4(3-)}}), is assimilated by phytoplankton and transformed into organic phosphorus compounds. Phytoplankton cell lysis releases cellular dissolved inorganic and organic phosphorus to the surrounding environment. Some of the organic phosphorus compounds can be hydrolyzed by enzymes synthesized by bacteria and phytoplankton and subsequently assimilated. The vast majority of phosphorus is remineralized within the water column, and approximately 1% of associated phosphorus carried to the deep sea by the falling particles is removed from the ocean reservoir by burial in sediments. A series of diagenetic processes act to enrich sediment pore water phosphorus concentrations, resulting in an appreciable benthic return flux of phosphorus to overlying bottom waters. These processes include

: (i) microbial respiration of organic matter in sediments,

: (ii) microbial reduction and dissolution of iron and manganese (oxyhydr)oxides with subsequent release of associated phosphorus, which connects the phosphorus cycle to the iron cycle,{{cite journal |last1=Burgin |first1=Amy J. |last2=Yang |first2=Wendy H. |last3=Hamilton |first3=Stephen K. |last4=Silver |first4=Whendee L. |date=2011 |title=Beyond carbon and nitrogen: how the microbial energy economy couples elemental cycles in diverse ecosystems |journal=Frontiers in Ecology and the Environment |language=en |volume=9 |issue=1 |pages=44–52 |doi=10.1890/090227 |bibcode=2011FrEE....9...44B |issn=1540-9309 |hdl=1808/21008 |hdl-access=free}} and

: (iii) abiotic reduction of iron (oxyhydr)oxides by hydrogen sulfide and liberation of iron-associated phosphorus.

Additionally,

: (iv) phosphate associated with calcium carbonate and

: (v) transformation of iron oxide-bound phosphorus to vivianite play critical roles in phosphorus burial in marine sediments.{{cite journal |author1=Kraal, P. |author2=Dijkstra, N. |author3=Behrends, T. |author4=Slomp, C.P. |date=May 2017 |title=Phosphorus burial in sediments of the sulfidic deep Black Sea: Key roles for adsorption by calcium carbonate and apatite authigenesis |journal=Geochimica et Cosmochimica Acta |volume=204 |pages=140–158 |doi=10.1016/j.gca.2017.01.042 |bibcode=2017GeCoA.204..140K|hdl=1874/347524 |hdl-access=free }}{{cite journal |author1=Defforey, D. |author2=Paytan, A. |date=2018 |title=Phosphorus cycling in marine sediments: Advances and challenges |journal=Chemical Geology |volume=477 |pages=1–11 |doi=10.1016/j.chemgeo.2017.12.002 |bibcode=2018ChGeo.477....1D}}

These processes are similar to phosphorus cycling in lakes and rivers.

Although orthophosphate ({{chem2|PO4(3-)}}), the dominant inorganic P species in nature, is oxidation state +5, certain microorganisms can use phosphonate and phosphite ( +3oxidation state) as a P source by oxidizing it to orthophosphate.{{cite journal |author1=Figueroa, I.A. |author2=Coates, J.D. |title=Microbial phosphite oxidation and its potential role in the global phosphorus and carbon cycles |journal=Advances in Applied Microbiology |volume=98 |pages=93–117 |date=2017 |pmid=28189156 |doi=10.1016/bs.aambs.2016.09.004 |isbn=978-0-12-812052-1}} Recently, rapid production and release of reduced phosphorus compounds has provided new clues about the role of reduced P as a missing link in oceanic phosphorus.{{cite journal |last1=Van Mooy |first1=B. A. S. |author-link1=Benjamin Van Mooy|last2=Krupke |first2=A. |last3=Dyhrman |first3=S. T. |author-link3=Sonya Dyhrman|last4=Fredricks |first4=H. F. |last5=Frischkorn |first5=K. R. |last6=Ossolinski |first6=J. E. |last7=Repeta |first7=D. J. |last8=Rouco |first8=M. |last9=Seewald |first9=J. D. |last10=Sylva |first10=S. P. |title=Major role of planktonic phosphate reduction in the marine phosphorus redox cycle |journal=Science |date=15 May 2015 |volume=348 |issue=6236 |pages=783–785 |doi=10.1126/science.aaa8181|pmid=25977548 |bibcode=2015Sci...348..783V |doi-access=free }}

The availability of phosphorus in an ecosystem is restricted by its rate of release during weathering. The release of phosphorus from apatite dissolution is a key control on ecosystem productivity.{{Cite book |last=Schlesinger |first=William H. |title=Biogeochemistry: an analysis of global change |date=2020 |publisher=Elsevier |isbn=978-0-12-814608-8 |edition=4 |location=SanDiego}} The primary mineral with significant phosphorus content, apatite [Ca₅(PO₄)₃OH] undergoes carbonation.{{cite journal | vauthors = Filippelli GM | date = 2002 | title = The Global Phosphorus Cycle. | journal = Reviews in Mineralogy and Geochemistry | volume = 48 | issue = 1 | pages = 391–425 | doi = 10.2138/rmg.2002.48.10 | bibcode = 2002RvMG...48..391F }}

Little of this released phosphorus is taken up by biota, as it mainly reacts with other soil minerals. This leads to phosphorus becoming unavailable to organisms in the later stage of weathering and soil development as it will precipitate into rocks. Available phosphorus is found in a biogeochemical cycle in the upper soil profile, while phosphorus found at lower depths is primarily involved in geochemical reactions with secondary minerals. Plant growth depends on the rapid root uptake of phosphorus released from dead organic matter in the biochemical cycle. Phosphorus is limited in supply for plant growth. Phosphates move quickly through plants and animals; however, the processes that move them through the soil or ocean are very slow, making the phosphorus cycle overall one of the slowest biogeochemical cycles.

Low-molecular-weight (LMW) organic acids are found in soils. They originate from the activities of various microorganisms in soils or may be exuded from the roots of living plants. Several of those organic acids are capable of forming stable organo-metal complexes with various metal ions found in soil solutions. As a result, these processes may lead to the release of inorganic phosphorus associated with aluminum, iron, and calcium in soil minerals. The production and release of oxalic acid by mycorrhizal fungi explain their importance in maintaining and supplying phosphorus to plants.{{cite journal | vauthors = Harrold SA, Tabatabai MA | title = Release of inorganic phosphorus from soils by low-molecular-weight organic acids. | journal = Communications in Soil Science and Plant Analysis | date = June 2006 | volume = 37 | issue = 9–10 | pages = 1233–45 | doi = 10.1080/00103620600623558 | bibcode = 2006CSSPA..37.1233H | s2cid = 84368363 }}

The availability of organic phosphorus to support microbial, plant and animal growth depends on the rate of their degradation to generate free phosphate. There are various enzymes such as phosphatases, nucleases and phytase involved for the degradation. Some of the abiotic pathways in the environment studied are hydrolytic reactions and photolytic reactions. Enzymatic hydrolysis of organic phosphorus is an essential step in the biogeochemical phosphorus cycle, including the phosphorus nutrition of plants and microorganisms and the transfer of organic phosphorus from soil to bodies of water.{{cite book |last1=Turner |first1=B.L. |title=Organic phosphorus in the environment |last2=Frossard |first2=E. |last3=Baldwin |first3=D.S. |publisher=CABI Publishing |year=2005 |isbn=978-0-85199-822-0}} Many organisms rely on the soil derived phosphorus for their phosphorus nutrition.{{cite web |last1=Sawyer |first1=John |last2=Creswell |first2=John |last3=Tidman |first3=Michael |title=Phosphorus Basics |url=https://crops.extension.iastate.edu/encyclopedia/phosphorus-basics#:~:text=Humans%20and%20other%20animals%20obtain,it%20available%20to%20all%20animals. |website=Iowa State University |access-date=20 April 2024}}

P deposition is quite important for ecosystem function, and is unevenly distributed across the planet.{{Cite journal |last1=Okin |first1=Gregory S. |last2=Mahowald |first2=Natalie |last3=Chadwick |first3=Oliver A. |last4=Artaxo |first4=Paulo |date=2004 |title=Impact of desert dust on the biogeochemistry of phosphorus in terrestrial ecosystems |url=https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2003GB002145 |journal=Global Biogeochemical Cycles |language=en |volume=18 |issue=2 |doi=10.1029/2003GB002145 |bibcode=2004GBioC..18.2005O |issn=1944-9224}} Although phosphorus does not have a major atmospheric component, phosphorus sediments can be moved during dust storms. Large dust events can counteract natural imbalances where P occurs and allow for production in areas that would otherwise be P-limited.{{Cite journal |last1=Herut |first1=Barak |last2=Collier |first2=Robert |last3=Krom |first3=Michael D. |date=2002 |title=The role of dust in supplying nitrogen and phosphorus to the Southeast Mediterranean |url=https://aslopubs.onlinelibrary.wiley.com/doi/10.4319/lo.2002.47.3.0870 |journal=Limnology and Oceanography |language=en |volume=47 |issue=3 |pages=870–878 |doi=10.4319/lo.2002.47.3.0870 |bibcode=2002LimOc..47..870H |issn=1939-5590|url-access=subscription }} This component of the phosphorus cycle has generally been overlooked by researchers, but its importance is starting to be understood. Most of Earth's phosphorus is in rocks, and dust contains weathered rock particles from this parent material.{{Cite journal |last1=Dey |first1=Rupak |last2=Sharma |first2=Seema B. |last3=Thakkar |first3=Mahesh G. |last4=Sarangi |first4=Ranjit Kumar |last5=Chowdhury |first5=Abhiroop |last6=Naz |first6=Aliya |date=2025-02-05 |title=Phosphorus transitions driven by cyclone biparjoy linked middle east North Africa (MENA) and Indian Thar Desert dust storm pathways in Asia's largest grassland |journal=Scientific Reports |language=en |volume=15 |issue=1 |pages=4321 |doi=10.1038/s41598-024-84634-3 |pmid=39910172 |pmc=11799440 |bibcode=2025NatSR..15.4321D |issn=2045-2322}} Dust also carries other nutrients such as potassium, calcium, and magnesium, making these storms of high importance to biogeochemical cycling.{{Cite journal |last1=Aciego |first1=S. M. |last2=Riebe |first2=C. S. |last3=Hart |first3=S. C. |last4=Blakowski |first4=M. A. |last5=Carey |first5=C. J. |last6=Aarons |first6=S. M. |last7=Dove |first7=N. C. |last8=Botthoff |first8=J. K. |last9=Sims |first9=K. W. W. |last10=Aronson |first10=E. L. |date=2017-03-28 |title=Dust outpaces bedrock in nutrient supply to montane forest ecosystems |url=https://www.nature.com/articles/ncomms14800 |journal=Nature Communications |language=en |volume=8 |issue=1 |pages=14800 |doi=10.1038/ncomms14800 |pmid=28348371 |bibcode=2017NatCo...814800A |issn=2041-1723|pmc=5379052 }}

The source of most large-scale dust storms are arid climates, including the Sahara Desert. Phosphorus carried in by wind from Northern Africa to the Amazon basin is thought to played a significant role supporting the rich biodiversity of the Amazon rainforest.

These events are called dust-loading.{{Cite journal |last1=Graham |first1=William F. |last2=Duce |first2=Robert A. |date=1979-08-01 |title=Atmospheric pathways of the phosphorus cycle |url=https://linkinghub.elsevier.com/retrieve/pii/0016703779901121 |journal=Geochimica et Cosmochimica Acta |volume=43 |issue=8 |pages=1195–1208 |doi=10.1016/0016-7037(79)90112-1 |bibcode=1979GeCoA..43.1195G |issn=0016-7037|url-access=subscription }} Smaller scale dust-loading events have been found to occur in midwestern US, where erosion of agricultural land provides ideal conditions for dust storms. As the frequency of these dust storms increases, the amount of P left in the actual agricultural plots declines, leading to an increase of P fertilizer application. Retention of plant-available P becomes more difficult as erosion increases.{{Cite journal |last1=Katra |first1=Itzhak |last2=Gross |first2=Avner |last3=Swet |first3=Nitzan |last4=Tanner |first4=Smadar |last5=Krasnov |first5=Helena |last6=Angert |first6=Alon |date=2016-04-20 |title=Substantial dust loss of bioavailable phosphorus from agricultural soils |journal=Scientific Reports |language=en |volume=6 |issue=1 |pages=24736 |doi=10.1038/srep24736 |pmid=27095629 |pmc=4837371 |bibcode=2016NatSR...624736K |issn=2045-2322}}

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{{Main|Eutrophication}}

Eutrophication is when waters are enriched by nutrients that lead to structural changes to the aquatic ecosystem such as algae bloom, deoxygenation, reduction of fish species. It does occur naturally, as when lakes age they become more productive due to increases in major limiting reagents such as nitrogen and phosphorus.{{Cite journal |last1=Yang |first1=Xiao-e |last2=Wu |first2=Xiang |last3=Hao |first3=Hu-lin |last4=He |first4=Zhen-li |date=March 2008 |title=Mechanisms and assessment of water eutrophication |journal=Journal of Zhejiang University. Science. B |volume=9 |issue=3 |pages=197–209 |doi=10.1631/jzus.B0710626 |issn=1673-1581 |pmc=2266883 |pmid=18357622}} For example, phosphorus can enter into lakes where it will accumulate in the sediments and the biosphere. It can also be recycled from the sediments and the water system allowing it to stay in the environment.{{cite journal | vauthors = Carpenter SR | title = Eutrophication of aquatic ecosystems: bistability and soil phosphorus | journal = Proceedings of the National Academy of Sciences of the United States of America | volume = 102 | issue = 29 | pages = 10002–5 | date = July 2005 | pmid = 15972805 | pmc = 1177388 | doi = 10.1073/pnas.0503959102 | url = https://www.pnas.org/content/pnas/102/29/10002.full.pdf | bibcode = 2005PNAS..10210002C | doi-access = free }} Anthropogenic effects can also cause phosphorus to flow into aquatic ecosystems as seen in drainage water and runoff from fertilized soils on agricultural land.{{cite journal |url= http://www.unep.or.jp/ietc/publications/short_series/lakereservoirs-3/3.asp |title = Where Nutrients Come From and How They Cause Entrophication | journal = Lakes and Reservoirs | volume = 3 | publisher = United Nations Environment Programme }} Additionally, eroded soils, which can be caused by deforestation and urbanization, can lead to more phosphorus and nitrogen being added to these aquatic ecosystems.{{cite journal |vauthors=Conley DJ, Paerl HW, Howarth RW, Boesch DF, Seitzinger SP, Havens KE, Lancelot C, Likens GE |date=February 2009 |title=Ecology. Controlling eutrophication: nitrogen and phosphorus |journal=Science |volume=323 |issue=5917 |pages=1014–5 |doi=10.1126/science.1167755 |pmid=19229022 |s2cid=28502866}} These all increase the amount of phosphorus that enters the cycle which has led to excessive nutrient intake in freshwater systems causing dramatic growth in algal populations. When these algae die, their putrefaction depletes the water of oxygen and can toxify the waters. Both these effects cause plant and animal death rates to increase as the plants take in and animals drink the poisonous water.{{cite web |title=The Effects: Dead Zones and Harmful Algal Blooms |url=https://www.epa.gov/nutrientpollution/effects-dead-zones-and-harmful-algal-blooms |website=Nutrient Pollution |date=12 March 2013 |publisher=United States Environmental Protection Agency |access-date=20 April 2024}}

File:Turquoise Swirls in the Black Sea.jpg

Oceanic ecosystems gather phosphorus through many sources, but it is mainly derived from weathering of rocks containing phosphorus which are then transported to the oceans in a dissolved form by river runoff.{{Cite journal |last1=Paytan |first1=Adina |last2=McLaughlin |first2=Karen |title=The Oceanic Phosphorus Cycle |journal=Chemical Reviews |date=2007 |volume=107 |issue=2 |pages=563–576 |doi=10.1021/cr0503613 |pmid=17256993 |issn=0009-2665}} Due to a dramatic rise in mining for phosphorus, it is estimated that humans have increased the net storage of phosphorus in soil and ocean systems by 75%.{{Cite journal |last1=Bennett |first1=Elena M. |last2=Carpenter |first2=Stephen R. |last3=Caraco |first3=Nina F. |title=Human Impact on Erodable Phosphorus and Eutrophication: A Global Perspective: Increasing accumulation of phosphorus in soil threatens rivers, lakes, and coastal oceans with eutrophication |journal=BioScience |date=2001 |volume=51 |issue=3 |pages=227–234 |doi=10.1641/0006-3568(2001)051[0227:HIOEPA]2.0.CO;2 |via=Elsevier Science Direct}} This increase in phosphorus has led to more eutrophication in ocean waters as phytoplankton blooms have caused a drastic shift in anoxic conditions seen in both the Gulf of Mexico{{Cite journal |last1=Rabalais |first1=Nancy N. |last2=Turner |first2=R. Eugene |last3=Wiseman |first3=William J. |title=Gulf of Mexico Hypoxia, A.K.A. "The Dead Zone" |url=https://www.annualreviews.org/doi/10.1146/annurev.ecolsys.33.010802.150513 |journal=Annual Review of Ecology and Systematics |date=2002 |volume=33 |issue=1 |pages=235–263 |doi=10.1146/annurev.ecolsys.33.010802.150513 |bibcode=2002AnRES..33..235R |issn=0066-4162|url-access=subscription }} and the Baltic Sea.{{Cite web |title=Eutrophication |url=https://www.bsag.fi/en/the-baltic-sea/eutrophication/ |access-date=2024-04-14 |website=Baltic Sea Action Group |language=en-GB}} Some research suggests that when anoxic conditions arise from eutrophication due to excess phosphorus, this creates a positive feedback loop that releases more phosphorus from oceanic reserves, exacerbating the issue.{{Cite journal |last1=Watson |first1=Andrew J. |last2=Lenton |first2=Timothy M. |last3=Mills |first3=Benjamin J. W. |date=2017-09-13 |title=Ocean deoxygenation, the global phosphorus cycle and the possibility of human-caused large-scale ocean anoxia |journal=Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences |language=en |volume=375 |issue=2102 |pages=20160318 |doi=10.1098/rsta.2016.0318 |issn=1364-503X |pmc=5559414 |pmid=28784709|bibcode=2017RSPTA.37560318W }} This could possibly create a self-sustaining cycle of oceanic anoxia where the constant recovery of phosphorus keeps stabilizing the eutrophic growth. Attempts to mitigate this problem using biological approaches are being investigated. One such approach involves using phosphorus accumulating organisms such as, Candidatus accumulibacter phosphatis, which are capable of effectively storing phosphorus in the form of phosphate in marine ecosystems.{{Cite journal |last1=Cakmak |first1=Ece Kendir |last2=Hartl |first2=Marco |last3=Kisser |first3=Johannes |last4=Cetecioglu |first4=Zeynep |title=Phosphorus mining from eutrophic marine environment towards a blue economy: The role of bio-based applications |journal=Water Research |date=2022 |volume=219 |doi=10.1016/j.watres.2022.118505 |bibcode=2022WatRe.21918505C |via=Elsevier Science Direct|doi-access=free |pmid=35561625 }} Essentially, this would alter how the phosphorus cycle exists currently in marine ecosystems. Currently, there has been a major influx of phosphorus due to increased agricultural use and other industrial applications, thus these organisms could theoretically store phosphorus and hold on to it until it could be recycled in terrestrial ecosystems which would have lost this excess phosphorus due to runoff.

Wetlands are frequently applied to solve the issue of eutrophication. Nitrate is transformed in wetlands to free nitrogen and discharged to the air.  Phosphorus is adsorbed by wetland soils which are taken up by the plants. Therefore, wetlands could help to reduce the concentration of nitrogen and phosphorus to remit eutrophication. However, wetland soils can only hold a limited amount of phosphorus. To remove phosphorus continually, it is necessary to add more new soils within the wetland from remnant plant stems, leaves, root debris, and undecomposable parts of dead algae, bacteria, fungi, and invertebrates.

Both N and P are widely used in agricultural fertilizers, as they are essential nutrients for plants. Human activity has resulted in an imbalance of normal N:P ratios, impacting the speed at which organisms synthesize proteins and DNA. In the last 40 years, the N:P ratio has increased from 19:1 to 30:1, meaning P is less available to ecosystems.{{Cite journal |last1=Peñuelas |first1=Josep |last2=Sardans |first2=Jordi |date=2022-01-21 |title=The global nitrogen-phosphorus imbalance |url=https://www.science.org/doi/10.1126/science.abl4827 |journal=Science |language=en |volume=375 |issue=6578 |pages=266–267 |doi=10.1126/science.abl4827 |pmid=35050668 |bibcode=2022Sci...375..266P |issn=0036-8075|url-access=subscription }} This imbalance is not only caused by more N pollution, but also because P is more likely to get trapped after water has been treated, preventing its release into ecosystems.

In an environment where neither nutrient is limited, where more P is present per N, organisms experience a faster growth rate. As this ratio increases, it is harder for organisms to grow. One example of organism response to this growing imbalance is rhizobia in legume root nodules. Research has shown that in low levels of P, the capacity for nitrogen-fixing bacteria to provide nutrients to the plant declines, negatively impacting both the host plant and its symbionts.{{Cite journal |last1=Zhong |first1=Yongjia |last2=Tian |first2=Jiang |last3=Li |first3=Xinxin |last4=Liao |first4=Hong |date=2023 |title=Cooperative interactions between nitrogen fixation and phosphorus nutrition in legumes |url=https://nph.onlinelibrary.wiley.com/doi/full/10.1111/nph.18593 |journal=New Phytologist |language=en |volume=237 |issue=3 |pages=734–745 |doi=10.1111/nph.18593 |pmid=36324147 |bibcode=2023NewPh.237..734Z |issn=1469-8137|url-access=subscription }} In addition, plants growing in P-limited environments will have more N content in their leaves.{{Cite journal |title=Interaction of nitrogen and phosphorus nutrition in determining growth |url=https://login.ezp3.lib.umn.edu/login?qurl=https://doi.org%2f10.1023%2fA%3a1022323215010 |access-date=2025-04-18 |journal=Plant and Soil |doi=10.1023/a:1022323215010 | date=2003 | volume=248 | pages=257–268 | bibcode=2003PlSoi.248..257D | issue=1–2 | vauthors = De Groot CC, Marcelis LF, Van Den Boogaard R, Kaiser WM, Lambers H | url-access=subscription }}

P and N are also unequally distributed across the globe, making certain geographical areas more favorable for crop growth than others. Disruption to these major biogeochemical cycles may exacerbate these inequities.{{Cite journal |last1=Du |first1=Enzai |last2=Terrer |first2=César |last3=Pellegrini |first3=Adam F. A. |last4=Ahlström |first4=Anders |last5=van Lissa |first5=Caspar J. |last6=Zhao |first6=Xia |last7=Xia |first7=Nan |last8=Wu |first8=Xinhui |last9=Jackson |first9=Robert B. |date=March 2020 |title=Global patterns of terrestrial nitrogen and phosphorus limitation |url=https://www.nature.com/articles/s41561-019-0530-4 |journal=Nature Geoscience |language=en |volume=13 |issue=3 |pages=221–226 |doi=10.1038/s41561-019-0530-4 |bibcode=2020NatGe..13..221D |hdl=1874/411553 |issn=1752-0908|hdl-access=free }}

File:Global - Global Fertilizer and Manure, Version 1 Phosphorus Fertilizer Application (6073486893).jpg

File:Global Global Fertilizer and Manure, Version 1 Phosphorus in Manure Production (6073493827).jpg

Nutrients are important to the growth and survival of living organisms and, hence, are essential for developing and maintaining healthy ecosystems. Humans have greatly influenced the phosphorus cycle by mining phosphate rock. For millennia, phosphorus was primarily brought into the environment by weathering phosphate-containing rocks, which would replenish the phosphorus normally lost to the environment through processes such as runoff, albeit on a very slow and gradual time scale.{{Cite journal |last1=Bouwman |first1=A. F. |last2=Beusen |first2=A. H. W. |last3=Billen |first3=G. |title=Human alteration of the global nitrogen and phosphorus soil balances for the period 1970-2050 |journal=Global Biogeochemical Cycles |date=2009 |volume=23 |issue=4 |doi=10.1029/2009GB003576 |bibcode=2009GBioC..23.0A04B |via=AGU Journals}} Since the 1840s, when the technology to mine and extract phosphorus became more prevalent, approximately 110 teragrams of phosphorus has been added to the environment.{{Cite journal |last1=Yuan |first1=Zengwei |last2=Jiang |first2=Songyan |last3=Sheng |first3=Hu |last4=Liu |first4=Xin |last5=Hua |first5=Hui |last6=Liu |first6=Xuewei |last7=Zhang |first7=You |title=Human Perturbation of the Global Phosphorus Cycle: Changes and Consequences |journal=Environmental Science & Technology |date=2018 |volume=52 |issue=5 |pages=2438–2450 |doi=10.1021/acs.est.7b03910 |pmid=29402084 |bibcode=2018EnST...52.2438Y |via=ACS Publications}} This trend appears to be continuing in the future as from 1900-2022, the amount of phosphorus mined globally has increased 72-fold,{{Cite web |title=Phosphate Rock - Historical Statistics (Data Series 140) {{!}} U.S. Geological Survey |url=https://www.usgs.gov/media/files/phosphate-rock-historical-statistics-data-series-140 |access-date=2024-04-14 |website=www.usgs.gov|date=22 February 2024 }} with an expected annual increase of 4%. Most of this mining is done to produce fertilizers which can be used on a global scale. However, at the rate humans are mining, the geological system can not quickly restore what is lost.{{Cite journal |last=Vaccari |first=David A. |date=2009 |title=Phosphorus: A Looming Crisis |journal=Scientific American |volume=300 |issue=6 |pages=54–59 |doi=10.1038/scientificamerican0609-54 |doi-broken-date=1 November 2024 |pmid=19485089 |bibcode=2009SciAm.300f..54V |issn=0036-8733}} Thus, researchers are examining ways to better recycle phosphorus in the environment, with one promising application including the use of microorganisms.{{Cite journal |last1=Cakmak |first1=Ece Kendir |last2=Hartl |first2=Marco |last3=Kisser |first3=Johannes |last4=Cetecioglu |first4=Zeynep |title=Phosphorus mining from eutrophic marine environment towards a blue economy: The role of bio-based applications |journal=Water Research |date=2022 |volume=219 |doi=10.1016/j.watres.2022.118505 |bibcode=2022WatRe.21918505C |via=Elsevier Science Direct|doi-access=free |pmid=35561625 }}{{Cite journal |last1=Slocombe |first1=Stephen P. |last2=Zúñiga-Burgos |first2=Tatiana |last3=Chu |first3=Lili |last4=Wood |first4=Nicola J. |last5=Camargo-Valero |first5=Miller Alonso |last6=Baker |first6=Alison |date=2020 |title=Fixing the Broken Phosphorus Cycle: Wastewater Remediation by Microalgal Polyphosphates |journal=Frontiers in Plant Science |volume=11 |page=982 |doi=10.3389/fpls.2020.00982 |doi-access=free |pmid=32695134 |pmc=7339613 |bibcode=2020FrPS...11..982S |issn=1664-462X}} Regardless, humans have had a profound impact on the phosphorus cycle with wide-reaching implications about food security, eutrophication, and the overall availability of the nutrient.{{Cite web |date=January 4, 2021 |title=Meeting the global phosphorus challenge will deliver food security and reduce pollution |url=http://www.unep.org/news-and-stories/story/meeting-global-phosphorus-challenge-will-deliver-food-security-and-reduce |access-date=2024-04-14 |website=UNEP |language=en}}

Other human processes can have detrimental effects on the phosphorus cycle, such as the repeated application of liquid hog manure in excess to crops. Applying biosolids may also increase available phosphorus in soil.{{cite journal | vauthors = Hosseinpur A, Pashamokhtari H | title=The effects of incubation on phosphorus desorption properties, phosphorus availability, and salinity of biosolids-amended soils | journal=Environmental Earth Sciences | date = June 2013 | volume=69 | issue=3 | pages=899–908 | doi=10.1007/s12665-012-1975-6 | bibcode=2013EES....69..899H | s2cid=140537340 }} In poorly drained soils or in areas where snowmelt can cause periodic waterlogging, reducing conditions can be attained in 7–10 days. This causes a sharp increase in phosphorus concentration in solution, and phosphorus can be leached. In addition, reducing the soil causes a shift in phosphorus from resilient to more labile forms. This could eventually increase the potential for phosphorus loss. This is of particular concern for the environmentally sound management of such areas, where disposal of agricultural wastes has already become a problem. It is suggested that soil water regimes used for organic waste disposal be considered when preparing waste management regulations.{{cite journal | vauthors = Ajmone-Marsan F, Côté D, Simard RR | title = Phosphorus transformations under reduction in long-term manured soils. | journal = Plant and Soil | date = April 2006 | volume = 282 | issue = 1–2 | pages = 239–50 | doi =10.1007/s11104-005-5929-6 | bibcode = 2006PlSoi.282..239A | s2cid = 23704883 }}

{{clear}}

• Planetary boundaries
• Oceanic carbon cycle

{{Reflist|25em}}

• {{cite web |url=http://www.lenntech.com/phosphorus-cycle.htm |title=Matter Cycles |volume=Part III: The phosphorus cycle |website=Lenntech |series=Water treatment & air purification |last=Holding |first=B.V. |year=2006}}
• {{cite web |url=http://www.enviroliteracy.org/article.php/480.html |website=Environmental Literacy Council |title=Phosphorus Cycle|date=10 July 2023 }}
• {{cite web |url=http://www.epa.gov/volunteer/stream/vms56.html |series=Monitoring and assessing water quality |title=section 5.6 Phosphorus |publisher=U.S. Environmental Protection Agency}}
• {{cite book |url=http://www.phschool.com/atschool/biology/Dragonfly/Student_Area/PHB_S_BK_index.html |url-status=dead |archive-date=2008-08-12 |archive-url=https://web.archive.org/web/20080812211636/http://www.phschool.com/atschool/biology/Dragonfly/Student_Area/PHB_S_BK_index.html |publisher=Prentice Hall |title=Biology |first1=Kenneth R. |last1=Miller |first2=Joseph |last2=Levine |year=2001}}
• {{cite web |url=http://filebox.vt.edu/users/chagedor/biol_4684/Cycles/Pcycle.html |archive-date=2008-09-14 |archive-url=https://web.archive.org/web/20080914101357/http://filebox.vt.edu/users/chagedor/biol_4684/Cycles/Pcycle.html |first=Katie |last=Corbin |title=The Phosphorus Cycle |series=Biogeochemical Cycles – Soil Microbiology |publisher=Virginia Polytechnic Institute and State University}}

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Category:Biogeochemical cycle

Category:Soil biology

Category:Soil chemistry

Category:Phosphorus