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Deep pore water profiles reflect enhanced microbial activity towards tidal flat margins |
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| Authors: | Melanie Beck Jürgen Köster Bert Engelen Jan M Holstein Antje Gittel Martin Könneke Thomas Riedel Kai Wirtz Heribert Cypionka Jürgen Rullkötter Hans-Jürgen Brumsack |
| Institution: | 1. Institute for Chemistry and Biology of the Marine Environment, Carl von Ossietzky University of Oldenburg, Carl-von-Ossietzky-Str. 9-11, 26129, Oldenburg, Germany 2. GKSS Research Center, Max-Planck-Stra?e 1, 21501, Geesthacht, Germany 3. Department of Biological Sciences, University of Aarhus, Ny Munkegade, Bdg. 1540, 8000, Aarhus, Denmark |
| Abstract: | Microbial activity in permeable tidal flat margin sediments is enhanced by two main processes. First, organic matter is supplied by rapid sedimentation at prograding tidal flat margins. Second, surface and deep pore water advection lead to a replenishment of the dissolved organic matter and sulfate pools. Increasing microbial activity towards the low water line is reflected in sulfate and methane profiles as well as in total cell numbers, sulfate reduction rates, and remineralization products. The impact of high sedimentation rates on pore water biogeochemistry is confirmed by inverse modeling reproducing the depth profiles obtained by measurements. In central parts of the tidal flats, low sedimentation rates and pore water flow velocities limit microbial activity despite the high availability of electron acceptors for microbial respiration such as sulfate. Therefore, tidal flat margins with high microbial activity are of special importance for budgeting biogeochemical cycling in tidal flat areas. |
| Keywords: | Pore water Sulfate reduction Methanogenesis Advection Sedimentation rate Integrated sediment model |
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