Metalloids in the high latitude North Atlantic Ocean: Sources and internal cycling

The concentrations and speciation of antimony, arsenic, and selenium were determined in horizontal transects and eight vertical profiles in the North Atlantic Ocean between 54°N to 68°N as a part of the 1993 IOC Contaminant Baseline Survey. Both arsenic and selenium display surface-water depletion and deep-water enrichment typical of nutrient-type elements, although selenium accumulates in deep waters to a much greater extent than arsenic. In contrast, antimony displays surface enrichment and a decrease with water mass age, consistent with scavenged behavior. Trivalent arsenic and antimony, and dimethyl arsinic acid, are restricted to the surface waters, but organic selenide is found in the youngest deep waters. A residence time of ca. 10 years for organic selenide is consistent with this behavior. Comparisons of allochthonous fluxes required to maintain the observed metalloid concentrations and atmospheric depositional fluxes measured on the islands of Bermuda and Ireland indicate that atmospheric deposition can be the dominant source of metalloids to the high latitude North Atlantic.