The impact of anoxia on Mn fluxes in the Chesapeake Bay

Release of Mn into bottom waters of the Chesapeake Bay occurs in massive quantities during summertime periods of anoxia. The measured flux is much greater than can be accounted for by diffusion from pore waters under normal concentration gradients and is enhanced by dissolution of Mn-oxides under low Eh conditions. Extrapolating flux rates to the area of the Bay which goes anoxic during the summer indicates that this internal cycling accounts for four times as much Mn entering Bay waters as the total annual input (soluble and suspended) from the Susquehanna River.