Biogenic sulfur compounds, such as dimethyl sulfide (DMS), its precursors dimethyl sulfoniopropionate (DMSP) and dimethyl sulfoxide (DMSO), and its atmospheric oxidation product, methane sulfonic acid (MSA), are important components of the global sulfur cycle that significantly impact global climate. The roles of DMSP and DMSO within the organisms that produce them, as well as their intracellular concentrations, are poorly understood. DMSO has been speculated to play a role in intracellular osmoregulation, cryoprotection and scavenging of reactive oxygen species, but its intracellular concentration in plankton has only been inferred. Quantitative measurement of the concentration of biogenic sulfur compounds in vivo is necessary to more completely understand their biogeochemistry. The principal investigator has developed methods for the quantitative analysis of biogenic sulfur compounds using Raman spectroscopy, which have resulted in the detection of DMSO with a sensitivity of <10 mM - far lower than the current estimates of its intracellular concentrations. The research will extend this technique to DMSP. The direct determination of the intracellular DMSP and DMSO, will allow the proposed roles of these compounds in phytoplankton to be investigated. Lastly, using field-collected cores, measurements will be made of the intracellular sulfur compounds as well as the concentration of molecular anions in the sea ice micro-environment. As an RUI project, successful completion of this work will have a substantial impact on undergraduate education in the Chemistry Department at the University of South Alabama, exposing undergraduates and, particularly, under-represented minorities in the sciences to cutting-edge research. It will provide financial support for their education and allow them to present research in journal articles and at technical meetings. Contacts with scientists in the field of Antarctic research at other institutions will give students the opportunity to interact with researchers in related fields, broadening their experience base.
