Editing Phosphate (section)

== Ecology ==<!-- Other articles link here -->
[[File:Annual mean sea surface phosphate (World Ocean Atlas 2009).png|left|thumb|Sea surface phosphate from the [[World Ocean Atlas]]]]
[[File:PhosphatetoNitrate.png|thumb|upright=1.25|Relationship of phosphate to nitrate uptake for [[photosynthesis]] in various regions of the ocean. Note that nitrate is more often limiting than phosphate. See the [[Redfield ratio]].]]

In ecological terms, because of its important role in biological systems, phosphate is a highly sought after resource. Once used, it is often a limiting nutrient in [[Environment (biophysical)|environments]], and its availability may govern the rate of growth of organisms. This is generally true of [[freshwater]] environments, whereas nitrogen is more often the limiting nutrient in marine (seawater) environments. Addition of high levels of phosphate to environments and to micro-environments in which it is typically rare can have significant ecological consequences. For example, blooms in the populations of some organisms at the expense of others, and the collapse of populations deprived of resources such as oxygen (see [[eutrophication]]) can occur. In the context of pollution, phosphates are one component of [[total dissolved solids]], a major indicator of water quality, but not all phosphorus is in a molecular form that algae can break down and consume.<ref>{{cite web|last=Hochanadel|first=Dave|title=Limited amount of total phosphorus actually feeds algae, study finds|url=http://www.lakescientist.com/2010/limited-amount-of-total-phosphorus-actually-feeds-algae-study-finds|publisher=Lake Scientist|access-date=June 10, 2012|date=December 10, 2010|quote=[B]ioavailable phosphorus – phosphorus that can be utilized by plants and bacteria – is only a fraction of the total, according to Michael Brett, a UW engineering professor ...}}</ref>

Calcium hydroxyapatite and calcite precipitates can be found around [[bacteria]] in [[alluvial]] topsoil.<ref name=Schmittner>{{cite journal |author=Schmittner KE, Giresse P |title=Micro-environmental controls on biomineralization: superficial processes of apatite and calcite precipitation in Quaternary soils, Roussillon, France |journal=Sedimentology |volume=46 |issue=3 |year=1999 |pages=463–76 |doi=10.1046/j.1365-3091.1999.00224.x|bibcode=1999Sedim..46..463S |s2cid=140680495 }}</ref> As clay minerals promote biomineralization, the presence of bacteria and clay minerals resulted in calcium hydroxyapatite and calcite precipitates.<ref name=Schmittner/>

Phosphate deposits can contain significant amounts of naturally occurring heavy metals. Mining operations processing [[phosphate rock]] can leave [[tailings]] piles containing elevated levels of [[cadmium]], [[lead]], [[nickel]], [[copper]], [[chromium]], and [[uranium]]. Unless carefully managed, these waste products can leach heavy metals into groundwater or nearby estuaries. Uptake of these substances by plants and marine life can lead to concentration of toxic heavy metals in food products.<ref>{{cite journal|last1 = Gnandi|first1 = K.|last2 = Tchangbedjil|first2 = G.|last3 = Killil|first3 = K.|last4 = Babal|first4 = G.|last5 = Abbel|first5 = E.|title = The Impact of Phosphate Mine Tailings on the Bioaccumulation of Heavy Metals in Marine Fish and Crustaceans from the Coastal Zone of Togo|periodical = Mine Water and the Environment|volume = 25|issue = 1|date = March 2006|pages = 56–62|doi = 10.1007/s10230-006-0108-4| bibcode=2006MWE....25...56G |s2cid = 129497587}}</ref>