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| Titel |
Quantifying in-situ gas hydrates at active seep sites in the eastern Black Sea using pressure coring technique |
| VerfasserIn |
K. U. Heeschen, M. Haeckel, I. Klaucke, M. K. Ivanov, G. Bohrmann |
| 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 ; 8, no. 12 ; Nr. 8, no. 12 (2011-12-08), S.3555-3565 |
| Datensatznummer |
250006240
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| Publikation (Nr.) |
 copernicus.org/bg-8-3555-2011.pdf |
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| Zusammenfassung |
| In the eastern Black Sea, we determined methane (CH4) concentrations,
gas hydrate volumes, and their vertical distribution from combined gas and
chloride (Cl−) measurements within pressurized sediment cores. The
total gas volume collected from the cores corresponded to concentrations of
1.2–1.4 mol CH4 kg−1 porewater at in-situ pressure, which is
equivalent to a gas hydrate saturation of 15–18% of pore volume and
amongst the highest values detected in shallow seep sediments. At the
central seep site, a high-resolution Cl− profile resolved the upper
boundary of gas hydrate occurrence and a continuous layer of hydrates in a
sediment column of 120 cm thickness. Including this information, a more
precise gas hydrate saturation of 22–24% pore volume could be
calculated. This volume was higher in comparison to a saturation calculated
from the Cl− profile alone, resulting in only 14.4%. The likely
explanation is an active gas hydrate formation from CH4 gas ebullition.
The hydrocarbons at Batumi Seep are of shallow biogenic origin (CH4 > 99.6%),
at Pechori Mound they originate from deeper thermocatalytic
processes as indicated by the lower ratios of C1 to C2–C3 and
the presence of C5. |
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