The biogeochemical cycles of antimony, arsenic, and selenium in the marine environment are complex, and include processes such as oxidation-reduction reactions, selective biological uptake, and kinetic controls on their chemical speciation. However, the potential toxicity of several metalloid species and the anthropogenic mobilization of these elements by fossil fuel combustion, are compelling reasons to fully understand the cycling of metalloid in the ocean. Of the three elements, very few data are available on antimony speciation and distributions in the open ocean. Selenium and arsenic have been extensively examined in the North Atlantic and Pacific Oceans, but several aspects of their cycling remain to be elucidated. This research utilizes samples collected from vertical profiles and horizontal transects in the North and South Atlantic, and eastern tropical North Pacific. Selective hydride generation methods will be used to analyze the samples, and the data will be augmented by nutrient and trace element results from other researchers working at the same stations. The primary objectives of this research will be: (1) to quantitatively describe the marine biogeochemical cycle of antimony; (2) to establish whether refractory organic arsenic compounds that have been found in coastal waters are present in oligotrophic waters, and if so, their role in the arsenic cycle; (3) to evaluate whether the chemical speciation of arsenic and antimony responds to suboxic conditions in the water column; and (4) to determine the fraction of dissolved selenium which is bound in soluble peptides and proteins.
