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| Titel |
Biogeochemistry of a low-activity cold seep in the Larsen B area, western Weddell Sea, Antarctica |
| VerfasserIn |
H. Niemann, D. Fischer, D. Graffe, K. Knittel, A. Montiel, O. Heilmayer, K. Nöthen, T. Pape, S. Kasten, G. Bohrmann, A. Boetius  , J. Gutt |
| 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 ; 6, no. 11 ; Nr. 6, no. 11 (2009-11-02), S.2383-2395 |
| Datensatznummer |
250004081
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| Publikation (Nr.) |
 copernicus.org/bg-6-2383-2009.pdf |
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| Zusammenfassung |
| First videographic indication of an Antarctic cold seep ecosystem was
recently obtained from the collapsed Larsen B ice shelf, western Weddell Sea
(Domack et al., 2005). Within the framework of the R/V Polarstern expedition
ANTXXIII-8, we revisited this area for geochemical, microbiological and
further videographical examinations. During two dives with ROV Cherokee
(MARUM, Bremen), several bivalve shell agglomerations of the
seep-associated, chemosynthetic clam Calyptogena sp. were found in the trough of the
Crane and Evans glacier. The absence of living clam specimens indicates that
the flux of sulphide and hence the seepage activity is diminished at
present. This impression was further substantiated by our geochemical
observations. Concentrations of thermogenic methane were moderately elevated
with 2 μM in surface sediments of a clam patch, increasing up to 9 μM
at a sediment depth of about 1 m in the bottom sections of the sediment
cores. This correlated with a moderate decrease in sulphate from about 28 mM
at the surface down to 23.4 mM, an increase in sulphide to up to 1.43 mM and
elevated rates of the anaerobic oxidation of methane (AOM) of up to 600 pmol cm−3 d−1
at about 1 m below the seafloor. Molecular analyses
indicate that methanotrophic archaea related to ANME-3 are the most likely
candidates mediating AOM in sediments of the Larsen B seep. |
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