Bryan A. Killingsworth, Ph.D.

My general focus is the application of light stable isotope tools for understanding perturbations to global and local geochemical cycles of sulfur that is linked, in turn, to cycling of carbon, oxygen, nitrogen, and metals. This focus is applied to modern systems, such as within small to large watersheds impacted by mining activities, and ancient records, such as those recording the Proterozoic oxygenation events and their links to extensive glacial episodes. Specific tools used are multiple sulfur and oxygen stable isotope techniques that can reveal detailed information on the sources and processing histories (e.g., sulfide oxidation and microbial sulfate reduction) affecting aqueous and rock sulfates. The advantage of sulfate’s sulfur and oxygen isotope signals is that they respond, on various time scales, to changes in redox; weathering; biological S, O, and C cycles; hydrology; and atmospheric gas concentrations.