ATMOSPHERIC INPUTS OF MANGANESE AND ALUMINUM TO THE SARGASSO SEA AND THEIR RELATION TO SURFACE-WATER CONCENTRATIONS

Atmospheric wet and dry deposition estimates for aluminium and manganese are presented for Bermuda and extrapolated to the Sargasso Sea. These deposition estimates are compared to average surface water concentrations of these elements to infer surface water residence times and also to constrain the solubility estimates for these metals in seawater after atmospheric deposition. For aluminium, atmospheric input fluxes and solubility are consistent with the seasonality of surface seawater concentration data and yield an average residence time in the upper 100 m of 6.5 yr. For manganese, it is more difficult to reconcile these various data sets suggesting that the solubility of atmospherically delivered manganese may have been underestimated and that photochemistry may play an important role in the surface water cycling of manganese. Together these effects suggest an estimated manganese residence times at the lower end of a 5-21 yr range for the upper 100 m of the water column.