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| Titel |
Threshold of carbonate saturation state determined by CO2 control experiment |
| VerfasserIn |
S. Yamamoto, H. Kayanne, M. Terai, A. Watanabe, K. Kato, A. Negishi, K. Nozaki |
| 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 ; 9, no. 4 ; Nr. 9, no. 4 (2012-04-17), S.1441-1450 |
| Datensatznummer |
250006952
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| Publikation (Nr.) |
 copernicus.org/bg-9-1441-2012.pdf |
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| Zusammenfassung |
| Acidification of the oceans by increasing anthropogenic CO2 emissions
will cause a decrease in biogenic calcification and an increase in carbonate
dissolution. Previous studies have suggested that carbonate dissolution will
occur in polar regions and in the deep sea where saturation state with
respect to carbonate minerals (Ω) will be <1 by 2100. Recent
reports demonstrate nocturnal carbonate dissolution of reefs, despite a
Ωa (aragonite saturation state) value of >1. This is
probably related to the dissolution of reef carbonate (Mg-calcite), which is
more soluble than aragonite. However, the threshold of Ω for the
dissolution of natural sediments has not been clearly determined. We
designed an experimental dissolution system with conditions mimicking those
of a natural coral reef, and measured the dissolution rates of aragonite in
corals, and of Mg-calcite excreted by other marine organisms, under
conditions of Ωa > 1, with controlled seawater pCO2. The
experimental data show that dissolution of bulk carbonate sediments sampled
from a coral reef occurs at Ωa values of 3.7 to 3.8. Mg-calcite
derived from foraminifera and coralline algae dissolves at Ωa
values between 3.0 and 3.2, and coralline aragonite starts to dissolve when
Ωa = 1.0. We show that nocturnal carbonate dissolution of coral
reefs occurs mainly by the dissolution of foraminiferans and coralline algae
in reef sediments. |
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