Sulfur isotope study of sulfide oxidation products: Great Marsh of Delaware and Green Lake NY

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Research Goals: Research will focus on describing the expression of sulfur isotope effects of sulfide oxidation products (polysulfides, polythionates, thiosulfate, sulfite, and sulfate) in two aqueous system case studies where sulfide oxidation occurs. We will collect samples from the Delaware Great Marsh during March, June, and August of 2009 and from Green Lake (a meromictic lake) during summer 2009. The aim of the study will be the isolation and isotopic characterization of the products of sulfide oxidation. The research will involve the adaptation of techniques for collection of these compounds so that measurements of the four sulfur isotopes can be made and with the purpose of characterizing and exploring the connections between the isotopic composition of the intermediates, pH, and biological activity. The overarching goal of this research effort is to develop a protocol based on four sulfur isotopes to place quantitative constraints on biological and abiotic pathways for sulfide oxidation in natural aquatic systems and in sediments. The work is rooted in the underlying premise that small isotope effects between products and reactants as well as between the variety of oxidation products will be expressed in different ways depending on the speciation of sulfur and the reaction pathways. This research is part of a larger effort underway by our group and others and extends our recent laboratory culture work with sulfate reducers, sulfur intermediate compound disproportionators, and biological sulfide oxidation.Broader Impacts of Proposed Activity: The results of this research will be prepared for publication in peer-reviewed journals. We anticipate that the outcomes of this research will carry implications for other studies of cycling of sulfur in geochemical systems and provide a context that can be used to inform our understanding of the significance of isotopic effects associated with sulfide oxidation in the sulfur cycle (present and past). The proposed activity will include involvement of undergraduates and will be incorporated into the broader activities of the PI.