Advective pore water input of nutrients to the Satilla River Estuary,Georgia, USA |
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| Institution: | 1. Cardiac Surgery Research Laboratory, Department of Surgery, Medical University of Vienna, Vienna, Austria;2. Department of Surgery, Cardiac Surgery, Medical University of Vienna, Vienna, Austria;3. Cardiac Surgery Research Laboratory Innsbruck, University Clinic for Cardiac Surgery, Innsbruck Medical University, Innsbruck, Austria;1. National Marine Science Centre, School of Environment, Science and Engineering, Southern Cross University, PO Box 4321, Coffs Harbour, NSW 2450, Australia;2. Centre for Coastal Biogeochemistry, School of Environment, Science and Engineering, Southern Cross University, PO Box 157, Lismore, NSW 2480, Australia;3. Institute for Chemistry and Biology of the Marine Environment (ICBM), Carl-von-Ossietzky University Oldenburg, D-26111 Oldenburg, Germany;4. Research Group for Marine Geochemistry (ICBM-MPI Bridging Group), Institute for Chemistry and Biology of the Marine Environment (ICBM), University of Oldenburg, Germany |
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| Abstract: | In situ benthic flux measurements, pore water nutrient profiles, water column nutrient distributions, sediment grain size distributions and side-scan sonar observations suggest that advective transport of pore waters may be a major input pathway of nutrients into the Satilla River Estuary (coastal Georgia, USA). In situ benthic chamber incubations demonstrate the occurrence of highly variable, but occasionally very large sea floor fluxes of silicate, phosphate, and ammonium. Locally occurring benthic microbial mineralization of organic matter, as estimated by S35-sulphate reduction rate measurements, is insufficient to support these large fluxes. We hypothesize that the observed interlayering of permeable, sandy sediments with fine-grained, organic-rich sediments in the estuary provides conduits for advective transport of pore water constituents out of the sediments. Because permeable layers may extend significant distances beneath the salt marsh, the large fluxes observed may be supported by remineralization occurring over large areas adjacent to the estuary. Advective transport may be induced by pressure gradients generated by a variety of processes, including landward recharge by meteoric or rain waters if sand layers extend far enough into the maritime coastal lands. Alternatively, tidal variations across the salt marsh sediment surface may hydraulically pump water through the sediment system. Because these fluxes appear to be concentrated into small layers, this source may be a significant input of nutrients to the estuary even if permeable, sandy layers comprise a very small proportion of the seabed. |
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