Editing Alkalinity (section)

{{Short description|Capacity of water to resist changes in pH that would make the water more acidic}}
{{distinguish|alkali|base (chemistry)}}

[[File:Annual mean sea surface alkalinity for the 1990s (GLODAP).png|thumb|right|200px|Sea surface alkalinity (from the [[Global Ocean Data Analysis Project|GLODAP]] [[climatology]]).]]

'''Alkalinity''' (from {{langx|ar|القلوية|al-qaly|lit=ashes of the [[saltwort]]}})<ref>{{cite Dictionary.com|alkali |access-date=2018-09-30}}</ref> is the capacity of [[water]] to resist [[Freshwater acidification|acidification]].<ref>{{cite news |url=https://www.water-research.net/index.php/the-role-of-alkalinity-citizen-monitoring |title=What is alkalinity? |publisher=Water Research Center |date=2014 |access-date=5 February 2018}}</ref> It should not be confused with [[base (chemistry)|basicity]], which is an absolute measurement on the [[pH]] scale. Alkalinity is the strength of a [[buffer solution]] composed of [[weak acid]]s and their [[conjugate acid|conjugate bases]]. It is measured by [[Titration|titrating]] the [[Solution (chemistry)|solution]] with an acid such as [[HCl]] until its pH changes abruptly, or it reaches a known endpoint where that happens. Alkalinity is expressed in units of concentration, such as meq/L ([[milliequivalents]] per [[liter]]), μeq/kg (microequivalents per kilogram), or mg/L CaCO<sub>3</sub> (milligrams per liter of [[calcium carbonate]]).<ref name="Dickson" />  Each of these measurements corresponds to an amount of acid added as a [[titrant]].

In [[Fresh water|freshwater]], particularly those on non-[[limestone]] terrains, alkalinities are low and involve a lot of ions. In the ocean, on the other hand, alkalinity is completely dominated by [[carbonate]] and [[bicarbonate]] plus a small contribution from [[borate]].<ref name=":5">{{Cite book |last1=Chester |first1=R. |url=https://www.wiley.com/en-us/Marine+Geochemistry%2C+3rd+Edition-p-9781118349090 |title=Marine geochemistry |last2=Jickells |first2=Tim |date=2012 |publisher=Wiley/Blackwell |isbn=978-1-118-34909-0 |edition=3rd |location=Chichester, West Sussex, UK |chapter=Chapter 9: Nutrients oxygen organic carbon and the carbon cycle in seawater |oclc=781078031}}</ref>

Although alkalinity is primarily a term used by [[Limnology|limnologists]]<ref>{{Citation |last=Mattson |first=M. D. |title=Alkalinity of Freshwater☆ |date=2014-01-01 |url=https://www.sciencedirect.com/science/article/pii/B9780124095489093970 |work=Reference Module in Earth Systems and Environmental Sciences |publisher=Elsevier |language=en |doi=10.1016/b978-0-12-409548-9.09397-0 |isbn=978-0-12-409548-9 |access-date=2023-01-09|url-access=subscription }}</ref> and [[Oceanography|oceanographers]],<ref name="Dickson">{{Cite journal | last1 = Dickson | first1 = Andrew G. | title = The development of the alkalinity concept in marine chemistry | doi = 10.1016/0304-4203(92)90047-E | journal =  Marine Chemistry | pages = 49–63 | year = 1992 | volume = 40 | issue = 1–2 | bibcode = 1992MarCh..40...49D }}</ref> it is also used by [[hydrologists]] to describe [[temporary hardness]]. Moreover, measuring alkalinity is important in determining a stream's ability to neutralize acidic pollution from [[Acid rain|rainfall]] or [[wastewater]]. It is one of the best measures of the sensitivity of the stream to acid inputs.<ref>{{cite news|url=http://water.epa.gov/type/rsl/monitoring/vms510.cfm|title=Total Alkalinity|access-date=6 March 2013|publisher=United States Environment Protection Agency}}</ref> There can be long-term changes in the alkalinity of streams and rivers in response to human disturbances such as acid rain generated by SO<sub>''x''</sub> and NO<sub>''x''</sub> emissions.<ref name="10.1021/es401046s">{{Cite journal | last1 = Kaushal | first1 = S. S. | last2 = Likens | first2 = G. E. | last3 = Utz | first3 = R. M. | last4 = Pace | first4 = M. L. | last5 = Grese | first5 = M. | last6 = Yepsen | first6 = M. | title = Increased river alkalinization in the Eastern U.S. | doi = 10.1021/es401046s | journal = Environmental Science & Technology | pages = 10302–10311 | year = 2013 | volume = 47 | issue = 18 | pmid = 23883395 }}</ref>