Aquatic Sciences Meeting, Albuquerque 2001

PC09 River and Margin Biogeochemistry

Date: Wednesday, February 14, 2001

Location: Southwest Hall

Wilson-Finelli, A, , Louisiana Universities Marine Consortium, Chauvin, USA, afinelli@lumcon.edu

Powell, R, T, Louisiana Universities Marine Consortium, Chauvin, USA, rpowell@lumcon.edu

NUTRIENT CYCLING IN THE MISSISSIPPI RIVER PLUME

The Mississippi river mixing zone is not confined to a typical estuary but is on the shelf and thus it has a direct impact on the biogeochemistry of the coastal ocean. Nutrients delivered by the river to the coastal zone are hypothesized to support high primary production leading to a large export of organic carbon. This carbon is then respired by bacteria leading to a seasonally suboxic zone in the bottom waters of the shelf. Data from two cruises will be discussed with emphasis on nitrogen and silicate cycling at high and low flow. Preliminary results indicate that little recycling occurs in the water column of the shelf and that upwelling is negligible with respect to delivery of nutrients. Therefore, all carbon that is respired must be fixed in the river plume and cannot come from recycyled nutrients. Our data will be compared to collaborators measurements of DOC, POC and primary productivity in order to accomplish the goal of understanding the production and fate of organic carbon in a river dominated coastal system.

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Aquatic Sciences Meeting, Albuquerque 2001

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