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| Titel |
Carbonate mineral saturation states in the East China Sea: present conditions and future scenarios |
| VerfasserIn |
W.-C. Chou, G.-C. Gong, C.-C. Hung, Y.-H. Wu |
| 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 ; 10, no. 10 ; Nr. 10, no. 10 (2013-10-11), S.6453-6467 |
| Datensatznummer |
250085361
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| Publikation (Nr.) |
 copernicus.org/bg-10-6453-2013.pdf |
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| Zusammenfassung |
| To assess the impact of rising atmospheric CO2 and eutrophication on the
carbonate chemistry of the East China Sea shelf waters, saturation states
(Ω) for two important biologically relevant carbonate minerals –
calcite (Ωc) and aragonite (Ωa) – were
calculated throughout the water column from dissolved inorganic carbon (DIC)
and total alkalinity (TA) data collected in spring and summer of 2009.
Results show that the highest Ωc (∼9.0) and
Ωa (∼5.8) values were found in surface water of the
Changjiang plume area in summer, whereas the lowest values
(Ωc = ∼2.7 and Ωa = ∼1.7) were
concurrently observed in the bottom water of the same area. This divergent
behavior of saturation states in surface and bottom waters was driven by
intensive biological production and strong stratification of the water
column. The high rate of phytoplankton production, stimulated by the enormous
nutrient discharge from the Changjiang, acts to decrease the ratio of DIC to
TA, and thereby increases Ω values. In contrast, remineralization of
organic matter in the bottom water acts to increase the DIC to TA ratio, and
thus decreases Ω values. The projected result shows that continued
increases of atmospheric CO2 under the IS92a emission scenario will
decrease Ω values by 40–50% by the end of this century, but both
the surface and bottom waters will remain supersaturated with respect to
calcite and aragonite. Nevertheless, superimposed on such Ω decrease
is the increasing eutrophication, which would mitigate or enhance the Ω
decline caused by anthropogenic CO2 uptake in surface and bottom waters,
respectively. Our simulation reveals that, under the combined impact of
eutrophication and augmentation of atmospheric CO2, the bottom water of
the Changjiang plume area will become undersaturated with respect to
aragonite (Ωa = ∼0.8) by the end of this century, which
would threaten the health of the benthic ecosystem. |
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