The Relation Between Pore Water Chemistry and Benthic Fluxes of Nutrients and Manganese in Narragansett Bay, Rhode Island

Benthic fluxes of dissolved nutrients and manganese from biologically disturbed, relatively unpolluted sediment in Narragansett Bay, Rhode Island, have been measured. Analyses of the vertical gradients of chemical species dissolved in pore waters and the uptake of22Nafrom the overlying water permits evaluation of the contribution of biological advection and molecular diffusion to the transport of dissolved materials across the sediment-water interface. The activity of bottom-dwelling organisms appears to be about as important as molecular diffusion in most cases. The sum of the independently estimated contributions by both mechanisms is in good agreement with integrated benthic fluxes measured in situ. Sulfate and oxygen oxidize comparable amounts of organic matter in these sediments.