Advective flow in sediments under the influence of compaction |
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Authors: | EKKEHARD HOLZBECHER |
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Institution: | Institute of Freshwater Ecology and Inland Fisheries (IGB) , Müggelseedamm 310, D-12587, Berlin, Germany E-mail: holzbecher@igb-berlin.de |
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Abstract: | Abstract Models on flow and transport in surface water sediments currently neglect compaction, although it is well understood that compaction is one of the major processes below the free fluid-sediment interface. Porosity changes in the sediment layers, as a result of compaction, are measured in almost all probes: porosity decreases with the distance from the surface water-sediment interface. This paper provides a rigorous derivation of basic flux terms for a frame of reference that is moving with the fluid-sediment interface. It is shown how burial rate, interface velocity, velocities of fluid and solid phase and porosity are connected—under steady-state conditions. It turns out that porosity and the velocities in a one-dimensional column can be directly computed from each other. These findings are important not only for the understanding of compaction-driven flow itself; they are crucial for all studies on storage and transport of chemical components in sediments. As mass fluxes across the sediment-water interface may be affected, there is an indirect link on surface water quality, making these findings relevant also for research on eutrophication of surface water bodies and/or on biogeochemical cycles. |
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Keywords: | sediments advection sedimentation compaction transport porous media |
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