Behavior of dissolved antimony, arsenic, and selenium in the Atlantic Ocean

Vertical profiles for dissolved antimony, arsenic, and selenium were obtained at four stations in the eastern basins of the North and South Atlantic Ocean, and on a surface-water transect from 24 ° S to 31 ° N. Total dissolved selenium displays surface-water depletion and deep-water enrichment, with organic selenide (selenium in soluble peptides) being the predominant species in surface waters and selenate predominating in deep waters. Although the concentrations of total selenium in surface waters of the Northern and Southern Hemispheres are similar, the ratio of inorganic to organic selenium is strongly influenced by the intensity of upwelling. Total inorganic arsenic is depleted in the surface waters of all stations, and increases to relatively constant deep-water concentrations (c. 20 nmol/l). In contrast, total inorganic antimony shows surface-water maxima at two stations. Although the average surface-water arsenic and antimony concentrations in the Northern and Southern Hemispheres are identical, there is some evidence for the atmospheric deposition of antimony. Overall, the cycling of the metalloids in the Atlantic is dominated by in situ biotic reactions, and modified by inputs from upwelling and atmospheric deposition.