Collaborative Research: Trace Distributions, Chemical Fluxes, and Distributary Comparisons in the Mixing Zone of the Mississippi River

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Estuaries and river plumes are productive, dynamic interfaces between the land and the ocean where chemical fluxes can be significantly altered. However, some important estuarine chemical fluxes and processes amongst them the flux of material from shelf bottom waters up into brackish surface waters and the flux of regenerated material off-shelf in bottom waters remain poorly understood. Scientists from the University of Southern Mississippi, the University of South Alabama, and the University of South Florida would determine the distributions of nutrients, trace elements, radium isotopes and other tracers in the outflow of the Mississippi River (1) to constrain water, nutrient and trace element fluxes; (2) to compare chemical distributions in different distributary mixing zones of an estuarine system to see how physiographic differences affect chemical fluxes; (3) to examine physical-chemical speciation of trace elements in a river plume/estuary mixing zone to see how sources and sinks of the trace elements are reflected in the speciation; and (4) to further develop and apply radium tracer methodology to these problems. Results of the field work would be incorporated into mass balance models of the Mississippi River outflow system to provide a more quantitative and systematic estimate of material fluxes. As regards broader impacts, this study would further our understanding of transport and cycling of nutrients and trace elements in river-dominated coastal systems. Understanding the fluxes of these elements in coastal and estuarine systems would allow for the development of management models and scenarios to predict the effect of management policies on the chemical and biological health of the coastal zone. This study would help foster new inter-institutional collaborations with two new investigators. Two graduate students from the University of Southern Mississippi, one graduate student from the University of South Alabama, and one graduate student and two undergraduate students from the University of South Florida would be supported and trained as part of this project.