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Biogeochemical processes in land-ocean interfaces, surface estuaries, subterranean estuaries and sediment-water interface
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Groundwater and biogeochemistry alter beach pore waters
Monday 7th @ 1050-1110, Conference Room 1
Willard S. Moore* , University of South Carolina, Columbia, SC, USA
Marc S. Humphries, University of the Witwatersrand, Johannesburg, South Africa
Claudia R. Benitez-Nelson, University of South Carolina, Columbia, SC, USA
Presenter Email: moore@geol.sc.edu |
| With each rise of the tide substantial sea water infiltrates beaches and returns to the ocean as the tide ebbs. Run up of waves onto beaches adds to this massive worldwide circulation. Water reentering the ocean has been changed chemically through biogeochemical reactions within the beach and by mixing with terrestrial groundwater. Thus, what goes out is substantially different chemically from what came in from the ocean. This paper will focus on how radium isotope tracers can help elucidate these processes. Specifically I will demonstrate that beaches have a wide range of inputs of both high and low salinity groundwater. These external sources plus reactions within the beach supply nutrients to beach pore waters and to the ocean as the tide recedes. One important contribution of radium isotopes is to delineate the inputs of high and low salinity groundwater and associated nutrients to beaches. In some cases the radium isotopes can quantify the delivery of nutrients to the coastal ocean through beach circulation; in other cases they fail. I will discuss several case studies where such inputs provide a significant nutrient source for the beach and one example of where they do not.
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