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| Titel |
Carbon isotopic evidence for microbial control of carbon supply to Orca Basin at the seawater–brine interface |
| VerfasserIn |
S. R. Shah, S. B. Joye, J. A. Brandes, A. P. McNichol |
| 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. 5 ; Nr. 10, no. 5 (2013-05-13), S.3175-3183 |
| Datensatznummer |
250018245
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| Publikation (Nr.) |
 copernicus.org/bg-10-3175-2013.pdf |
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| Zusammenfassung |
| Orca Basin, an intraslope basin on the Texas-Louisiana continental slope,
hosts a hypersaline, anoxic brine in its lowermost 200 m in which limited
microbial activity has been reported. This brine contains a large reservoir
of reduced and aged carbon, and appears to be stable at decadal time scales:
concentrations and isotopic composition of dissolved inorganic (DIC) and
organic carbon (DOC) are similar to measurements made in the 1970s. Both DIC
and DOC are more "aged" within the brine pool than in overlying water, and
the isotopic contrast between brine carbon and seawater carbon is much
greater for DIC than DOC. While the stable carbon isotopic composition of
brine DIC points towards a combination of methane and organic carbon
remineralization as its source, radiocarbon and box model results point to
the brine interface as the major source region for DIC, allowing for only
limited oxidation of methane diffusing upwards from sediments. This
conclusion is consistent with previous studies that identify the
seawater–brine interface as the focus of microbial activity associated with
Orca Basin brine. Isotopic similarities between DIC and DOC suggest a
different relationship between these two carbon reservoirs than is typically
observed in deep ocean basins. Radiocarbon values implicate the
seawater–brine interface region as the likely source region for DOC to the
brine as well as DIC. |
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