Manganese cycling in the Newport River estuary, North Carolina

Dissolved manganese (Mn) was measured in the Newport River estuary, North Carolina, in October 1974, February 1975, and APRIL 1975 by extraction on Chelex-100 resin and subsequent analysis by flameless atomic absorption spectrophotometry. Dissolved Mn concentrations at intermediate salinities were in excess of those predicted by conservative mixing of inflowing river and ocean water, with maxima between 4{per thousand} and 14{per thousand} salinity. Reduction and solubilization of Mn in bottom sediments in the upper estuary probably supplies much of the added dissolved Mn. Fixation of dissolved Mn on particles takes place in the lower estuary with subsequent upstream recycling. The export of dissolved Mn from the estuary in excess of that input by the river is probably balanced by continuous traction flows of river-derived bed sediment or pulse inputs of suspended sediment in storm runoff followed by partial solubilization. 15 refs., 4 figs., 1 tab