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| Titel |
Imprint of past and present environmental conditions on microbiology and biogeochemistry of coastal Quaternary sediments |
| VerfasserIn |
M. Beck, T. Riedel, J. Graue, J. Köster, N. Kowalski, C. S. Wu, G. Wegener, Y. Lipsewers, H. Freund, M. E. Böttcher, H.-J. Brumsack, H. Cypionka, J. Rullkötter, B. Engelen |
| 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. 1 ; Nr. 8, no. 1 (2011-01-07), S.55-68 |
| Datensatznummer |
250005345
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| Publikation (Nr.) |
 copernicus.org/bg-8-55-2011.pdf |
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| Zusammenfassung |
To date, North Sea tidal-flat sediments have been intensively studied down
to a depth of 5 m below seafloor (mbsf). However, little is known about
the biogeochemistry, microbial abundance, and activity of sulfate reducers
as well as methanogens in deeper layers. In this study, two 20 m-long
cores were retrieved from the tidal-flat area of Spiekeroog Island, NW
Germany. The drill sites were selected with a close distance of 900 m
allowing to compare two depositional settings: first, a paleo-channel filled
with Holocene sediments and second, a mainly Pleistocene sedimentary
succession. Analyzing these cores, we wanted to test to which degree the
paleo-environmental imprint is superimposed by present processes.
In general, the numbers of bacterial 16S rRNA genes are one to two orders of
magnitude higher than those of Archaea. The abundances of key genes for sulfate
reduction and methanogenesis (dsrA and mcrA) correspond to the sulfate and methane
profiles. A co-variance of these key genes at sulfate-methane interfaces and
enhanced ex situ AOM rates suggest that anaerobic oxidation of methane may
occur in these layers. Microbial and biogeochemical profiles are vertically
stretched relative to 5 m-deep cores from shallower sediments in the same
study area, but still appear compressed compared to deep sea sediments. Our
interdisciplinary analysis shows that the microbial abundances and metabolic
rates are elevated in the Holocene compared to Pleistocene sediments.
However, this is mainly due to present environmental conditions such as pore
water flow and organic matter availability. The paleo-environmental imprint
is still visible but superimposed by these processes. |
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