Margins receiving inputs from large rivers represent the extremes of continental shelf systems in carbon cycling and fluxes. Recent findings in the vicinity of the Mississippi River plume show highly variable carbon fluxes and highlight the need for greater spatial and temporal coverage, as well as an assessment of the underlying community metabolism driving patterns in surface CO2. Scientists from the University of Southern Mississippi and the University of Georgia propose to test the hypothesis that large river margin water columns exhibit extreme seasonal and spatial variability in air-sea CO2 fluxes, characterized by localized uptake driven largely by high rates of autotrophic production and loss of CO2 driven by high terrestrial inputs and heterotrophic respiration. Because of the extreme variability in this system, constructing and characterizing spatially and temporally integrated air-sea fluxes cannot be done by extrapolation or interpolation solely from discrete field measurements. As such, the investigators plan to carry out a multidisciplinary study that includes continuous, shipboard and satellite derived assessments of CO2 fluxes, as well as process measurements of planktonic net community metabolism, carbon fixation rates and box modeling to simulate river plume mixing to provide new estimates of the emissions and uptake of CO2 and the factors regulating these processes in coastal margins.
As regards broader impacts, one postdoc from the University of Southern Mississippi and one graduate student from the University of Georgia would be supported and trained as part of this project.
