编辑“︁钙”︁（章节）

===地球化学循环===
{{Main|碳酸盐-硅酸盐循环}}
[[钙循环]]提供了{{le|地质构造运动|Tectonics}}、[[气候]]和[[碳循环]]之间的联系。山脉的隆起会使[[花岗岩]]等含钙岩石经受化学风化作用，并将Ca<sup>2+</sup>离子释放到地表水中。这些离子之后会被运输到海洋，和海水溶解的CO<sub>2</sub>反应生成[[石灰石]]（{{chem|CaCO|3}}），沉降到海底并合并到新的岩石中。海水溶解的CO<sub>2</sub>、[[碳酸根]]和[[碳酸氢根]]都属于“[[总无机碳|溶解无机碳]]”（DIC）。<ref name="Berner" />

实际反应要更复杂，涉及CO<sub>2</sub>和水在海水[[pH]]下反应而成的碳酸氢根离子（HCO{{su|b=3|p=−}}）：
:{{chem|Ca|2+}} + 2{{chem|HCO|3|-}} → {{chem|CaCO|3|link=石灰石}}<sub>([[固体|s]])</sub> + {{chem|CO|2}} + {{chem|H|2|O}}
在海水的pH下，大部分溶解的CO<sub>2</sub>都会立刻变成{{chem|HCO|3|-}}。该反应导致一分子CO<sub>2</sub>从海洋或大气净传输到[[岩石圈]]。<ref>{{cite web|author = Zeebe|date = 2006|url = http://www.eoearth.org/article/Marine_carbonate_chemistry|title = Marine carbonate chemistry|publisher = National Council for Science and the Environment|access-date = 2010-03-13|archive-date = 2011-09-03|archive-url = https://web.archive.org/web/20110903000607/http://www.eoearth.org/article/Marine_carbonate_chemistry}}</ref>反应的结果是化学风化释放的每个Ca<sup>2+</sup>离子最终会从地表（大气、海洋、土壤和生物体）中去除一个CO<sub>2</sub>分子，并将其储存到碳酸盐矿物中停留数亿年。因此，岩石中钙的风化作用会清除海洋和大气中的CO<sub>2</sub>，对气候产生强烈的长期影响。<ref name="Berner">{{Cite journal|last1=Berner|first1=Robert|title= The long-term carbon cycle, fossil fuels and atmospheric composition |url=https://archive.org/details/sim_nature-uk_2003-11-20_426_6964/page/322|journal=Nature|date=2003|volume=426|pages= 323–26|doi=10.1038/nature02131|pmid=14628061|issue=6964|bibcode = 2003Natur.426..323B |s2cid=4420185}}</ref><ref>{{Cite journal|title = A negative feedback mechanism for the long-term stabilization of Earth's surface temperature|journal = Journal of Geophysical Research: Oceans|date = 1981-10-20|issn = 2156-2202|pages = 9776–82|volume = 86|issue = C10|doi = 10.1029/JC086iC10p09776|language = en|first1 = James C. G.|last1 = Walker|first2 = P. B.|last2 = Hays|first3 = J. F.|last3 = Kasting|bibcode=1981JGR....86.9776W}}</ref>