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| Titel |
Reconsidering the role of carbonate ion concentration in calcification by marine organisms |
| VerfasserIn |
L. T. Bach |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1726-4170
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| Digitales Dokument |
URL |
| Erschienen |
In: Biogeosciences ; 12, no. 16 ; Nr. 12, no. 16 (2015-08-19), S.4939-4951 |
| Datensatznummer |
250118067
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| Publikation (Nr.) |
 copernicus.org/bg-12-4939-2015.pdf |
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| Zusammenfassung |
| Marine organisms precipitate 0.5–2.0 Gt of carbon as calcium carbonate
(CaCO3) every year with a profound impact on global biogeochemical
element cycles. Biotic calcification relies on calcium ions (Ca2+) and usually on bicarbonate ions (HCO3−) as CaCO3 substrates and
can be inhibited by high proton (H+) concentrations. The seawater
concentration of carbonate ions (CO32−) and the
CO32−-dependent CaCO3 saturation state (ΩCaCO3)
seem to be irrelevant in this production process. Nevertheless,
calcification rates and the success of calcifying organisms in the oceans
often correlate surprisingly well with these two carbonate system
parameters. This study addresses this dilemma through the rearrangement of
carbonate system equations which revealed an important proportionality
between [CO32−] or ΩCaCO3and the ratio of
[HCO3−] to [H+]. Due to this proportionality, calcification
rates will always correlate as well with [HCO3−] / [H+] as they do with [CO32−] or ΩCaCO3 when temperature, salinity,
and pressure are constant. Hence, [CO32−] and ΩCaCO3
may simply be very good proxies for the control by
[HCO3−] / [H+], where [HCO3−] serves as the inorganic
carbon substrate and [H+] functions as a calcification inhibitor. If
the "substrate–inhibitor ratio" (i.e., [HCO3−] / [H+]) rather
than [CO32−] or ΩCaCO3 controls biotic CaCO3
formation, then some of the most common paradigms in ocean acidification
research need to be reviewed. For example, the absence of a latitudinal
gradient in [HCO3−] / [H+] in contrast to [CO32−] and
ΩCaCO3 could modify the common assumption that high latitudes
are affected most severely by ocean acidification. |
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