A comparison of atmospheric inputs and deep‐ocean particle fluxes for the Sargasso Sea

Trace metal distributions in ocean waters are dominated by internal recycling processes. However, fluxes out of the water column must balance inputs if steady state is to be maintained. We use deep‐sea particle fluxes at 3200 m in the Sargasso Sea as measured by sediment traps to define the flux to the sediments beneath the Sargasso Sea and compare this flux to the atmospheric input for a group of trace metals. Despite the uncertainties associated with the comparison, several important features are revealed. For elements predominantly associated with crustal particles (Al, Mn, Fe, and V), lateral advection provides a significant part of the deep‐sea particle flux. For Cd, Cu, Ni, Pb, and Zn this lateral component is minor, and atmospheric inputs to the Sargasso Sea exceed deep‐sea particle fluxes. These excesses appear to be consistent with calculations of the export of these metals from the Sargasso Sea arising from ocean boundary scavenging (Pb) and release from decomposing organic matter in the southward flowing North Atlantic Deep Water (Cd, Cu, Ni, and Zn). In the atmospheric deposition itself, wet deposition exceeds dry deposition for Cd, Cu, Mn, Ni, Pb, and Zn, while wet and dry deposition are of similar magnitudes for V, Fe, and Al.