Editing Calcium carbonate (section)

===Pollution mitigation===
In 1989, a researcher, Ken Simmons, introduced {{chem2|CaCO3}} into the Whetstone Brook in [[Massachusetts]].<ref name="New York Times">{{cite news|agency = [[Associated Press]]|title = Limestone Dispenser Fights Acid Rain in Stream|date = 13 June 1989|url = https://www.nytimes.com/1989/06/13/science/limestone-dispenser-fights-acid-rain-in-stream.html|work = The New York Times|access-date = 27 July 2018|archive-date = 28 July 2018|archive-url = https://web.archive.org/web/20180728002911/https://www.nytimes.com/1989/06/13/science/limestone-dispenser-fights-acid-rain-in-stream.html|url-status = live}}</ref> His hope was that the calcium carbonate would counter the acid in the stream from acid rain and save the trout that had ceased to spawn. Although his experiment was a success, it did increase the amount of aluminium ions in the area of the brook that was not treated with the limestone. This shows that {{chem2|CaCO3}} can be added to neutralize the effects of acid rain in [[river]] ecosystems. Currently calcium carbonate is used to neutralize acidic conditions in both soil and water.<ref name=env>{{cite web|title=Environmental Uses for Calcium Carbonate|date=6 September 2012|url=http://www.congcal.com/markets/environmental/|publisher=Congcal|access-date=5 August 2013|archive-date=4 January 2014|archive-url=https://web.archive.org/web/20140104055647/http://www.congcal.com/markets/environmental/|url-status=dead}}</ref><ref name="Schreiber-1988">{{cite journal|last = Schreiber|first = R. K.|title = Cooperative federal-state liming research on surface waters impacted by acidic deposition|year = 1988|journal = Water, Air, & Soil Pollution|volume = 41|issue = 1|pages = 53–73|doi = 10.1007/BF00160344|bibcode = 1988WASP...41...53S|s2cid = 98404326|url = https://link.springer.com/article/10.1007%2FBF00160344|access-date = 28 August 2017|archive-date = 10 January 2018|archive-url = https://web.archive.org/web/20180110054856/https://link.springer.com/article/10.1007%2FBF00160344|url-status = live}}</ref> Since the 1970s, such ''liming'' has been practiced on a large scale in Sweden to mitigate acidification and several thousand lakes and streams are limed repeatedly.<ref name="Guhrén-2006">{{Cite journal |doi= 10.1007/s10933-006-9014-9 |title= Liming placed in a long-term perspective: A paleolimnological study of 12 lakes in the Swedish liming program |journal= Journal of Paleolimnology |volume= 37 |issue= 2 |pages= 247–258 |year= 2006 |last1= Guhrén |first1= M. |last2= Bigler |first2= C. |last3= Renberg |first3= I. |bibcode= 2007JPall..37..247G |s2cid= 129439066}}</ref>

Calcium carbonate is also used in [[flue-gas desulfurization]] applications eliminating harmful {{chem2|SO2}} and {{chem2|NO2}} emissions from coal and other fossil fuels burnt in large fossil fuel power stations.<ref name=env/>