CS33 Sediment-Water Interactions
Date: Wednesday, June 12, 2002
Time: 5:00:00 PM
Location: Saanich
 
PrechtE, Max-Planck-Institute for Marine Microbiology, Bremen, Germany, eprecht@mpi-bremen.de
Huettel, M, , Max-Planck-Institute for Marine Microbiology, Bremen, Germany, mhuettel@mpi-bremen.de
 
ADVECTIVE SEDIMENT-WATER SOLUTE EXCHANGE DRIVEN BY SURFACE GRAVITY WAVES AND ITS ECOLOGICAL IMPLICATIONS
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Pore water exchange in shallow water permeable sediments caused by surface gravity waves was quantified in wave tank experiments. We conducted the experiments with clean fine sand (0.2 mm md) and Rhodamine-stained porewater. Initially, wave pumping results in moderate tracer release from the sediment. As soon as ripples are formed, the interfacial exchange rate increases sharply (10 times diffusive release) due to advective pore water exchange caused by the interaction of boundary currents and surface topography. The evolving porewater flow field produces a regular pattern of intrusion and release zones that migrates with the ripple movement. The depth of porewater washout is linked to ripple amplitudes. In-situ measurements in a shallow sandy subtidal zone in the Mediterranean confirmed the laboratory processes for natural settings. Our experiments allow a quantitative approach to the advective processes that occur when oscillating currents move over an initially smooth and then rippled permeable sediment bed. We discuss significance and ecological consequences of this wave induced interfacial transport process.