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| Titel |
A rapid transition from ice covered CO2–rich waters to a biologically mediated CO2 sink in the eastern Weddell Gyre |
| VerfasserIn |
D. C. E. Bakker, M. Hoppema, M. Schröder, W. Geibert, H. J. W. Baar |
| 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 ; 5, no. 5 ; Nr. 5, no. 5 (2008-09-30), S.1373-1386 |
| Datensatznummer |
250002833
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| Publikation (Nr.) |
 copernicus.org/bg-5-1373-2008.pdf |
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| Zusammenfassung |
| Circumpolar Deep Water (CDW), locally called Warm Deep Water (WDW), enters
the Weddell Gyre in the southeast, roughly at 25° E to 30° E. In
December 2002 and January 2003 we studied the effect of entrainment of WDW
on the fugacity of carbon dioxide (fCO2) and dissolved inorganic carbon
(DIC) in Weddell Sea surface waters. Ultimately the fCO2 difference
across the sea surface drives air-sea fluxes of CO2. Deep CTD sections
and surface transects of fCO2 were made along the Prime Meridian, a
northwest-southeast section, and along 17° E to 23° E during cruise
ANT XX/2 on FS Polarstern. Upward movement and entrainment of WDW into the winter
mixed layer had significantly increased DIC and fCO2 below the sea ice
along 0° W and 17° E to 23° E, notably in the southern Weddell
Gyre. Nonetheless, the ice cover largely prevented outgassing of CO2 to
the atmosphere. During and upon melting of the ice, biological activity
rapidly reduced surface water fCO2 by up to 100 μatm, thus
creating a sink for atmospheric CO2. Despite the tendency of the
surfacing WDW to cause CO2 supersaturation, the Weddell Gyre may well
be a CO2 sink on an annual basis due to this effective mechanism
involving ice cover and ensuing biological fCO2 reduction. Dissolution
of calcium carbonate (CaCO3) in melting sea ice may play a minor role
in this rapid reduction of surface water fCO2. |
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