| Summary: | Submitted in partial fulfillment of the requirements for the degree of Master of Science at the Massachusetts Institute of Technology and the Woods Hole Oceanographic Institution February 2013 Thiol substances can form stable complexes with metals (especially copper and mercury) in the surface ocean that can impact cycling and bioavailability of those elements. In this study, I present seven concentration profiles of cysteine and glutathione, two low-molecular weight thiols, from the coastal northwest Atlantic Ocean and the Bermuda Atlantic Time Series (BATS) sampling site in the Sargasso Sea, a first for these regions. These two thiols were found in the upper 200 meters of the ocean at all sites, and the total thiol concentration varied from 0.2 to 3.2 nM. The highest concentration of both thiols was found at the deep chlorophyll maximum in most samples. Thiol concentrations were higher on the continental shelf than in the open ocean. The observed distribution of cysteine and glutathione and thermodynamic stability of copper complexes suggests that Cu(I)-dithiol complexes may be the dominant surface ocean copper and thiol species. Mercury-thiol complexes were also present in thermodynamically modeled seawater, which may provide a vector for mercury uptake in the surface ocean. The work in this thesis was funded by NSF OCE grant 1132515 and NSF EAR grant 1119373. Funding was also provided by an internal source at WHOI for the first year of this work.
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