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| Titel |
Saturated CO2 inhibits microbial processes in CO2-vented deep-sea sediments |
| VerfasserIn |
D. Beer, M. Haeckel, J. Neumann, G. Wegener, F. Inagaki, A. Boetius  |
| 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. 8 ; Nr. 10, no. 8 (2013-08-26), S.5639-5649 |
| Datensatznummer |
250085308
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| Publikation (Nr.) |
 copernicus.org/bg-10-5639-2013.pdf |
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| Zusammenfassung |
| This study focused on biogeochemical processes and microbial activity in
sediments of a natural deep-sea CO2 seepage area (Yonaguni Knoll IV
hydrothermal system, Japan). The aim was to assess the influence of the
geochemical conditions occurring in highly acidic and CO2 saturated
sediments on sulfate reduction (SR) and anaerobic methane oxidation (AOM).
Porewater chemistry was investigated from retrieved sediment cores and in
situ by microsensor profiling. The sites sampled around a sediment-hosted
hydrothermal CO2 vent were very heterogeneous in porewater chemistry,
indicating a complex leakage pattern. Near the vents, droplets of liquid
CO2 were observed emanating from the sediments, and the pH reached
approximately 4.5 in a sediment depth > 6 cm, as determined in situ by
microsensors. Methane and sulfate co-occurred in most sediment samples from
the vicinity of the vents down to a depth of 3 m. However, SR and AOM were
restricted to the upper 7–15 cm below seafloor, although neither
temperature, low pH, nor the availability of methane and sulfate could be
limiting microbial activity. We argue that the extremely high subsurface
concentrations of dissolved CO2 (1000–1700 mM), which disrupt the
cellular pH homeostasis, and lead to end-product inhibition. This limits life
to the surface sediment horizons above the liquid CO2 phase, where less
extreme conditions prevail. Our results may have to be taken into
consideration in assessing the consequences of deep-sea CO2
sequestration on benthic element cycling and on the local ecosystem state. |
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