Silver in the North Pacific ocean

The distribution of silver in the North Pacific, determined using a suite of surface and subsurface samples, was found to be controlled by both natural and anthropogenic processes. Within the water column, silver was distributed as a typical nutrient-type element, as was previously observed in other oceanic waters. However, surface water concentrations of silver near Japan were the highest ever measured for the open ocean (up to 12 pM) and are considered evidence of anthropogenic contamination. Since prevailing wind flow during this study was westerly, this enrichment is attributed to aeolian fluxes of Asian industrial aerosols to North Pacific surface waters. Additional evidence of the impact atmospheric inputs of silver have on the North Pacific water column is shown by comparisons of intermediate depth waters analyzed during this study and during a study carried out 20 years previously that indicate temporal increases in industrial silver fluxes to these waters. Measurements from this study also confirm that silver is significantly correlated with dissolved silica, although the correlations are measurably different between the Atlantic and Pacific basins, and that the ratio of silver to copper is diagnostic of individual water masses in the Pacific and can be used as a geochemical tracer of ocean circulation. Overall, data obtained during this study enable a complete preliminary survey of silver in the World Ocean.