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- Title
Imprint of past and present environmental conditions on microbiology and biogeochemistry of coastal Quaternary sediments.
- Authors
Beck, M.; Riedel, T.; Graue, J.; Köster, J.; Kowalski, N.; Wu, C. S.; Wegener, G.; Lipsewers, Y.; Freund, H.; Böttcher, M. E.; Brumsack, H.-J.; Cypionka, H.; Rullkötter, J.; Engelen, B.
- Abstract
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 20m-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 su-perimposed 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 (dsr A 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 comparedto 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 avail-ability. The paleo-environmental imprint is still visible but superimposed by these processes.
- Subjects
MICROBIOLOGY; BIOGEOCHEMISTRY; COASTS; SEDIMENTS; WATER depth; RNA; ORGANIC compounds
- Publication
Biogeosciences, 2011, Vol 8, Issue 1, p55
- ISSN
1726-4170
- Publication type
Article
- DOI
10.5194/bg-8-55-2011