Spring 2008 Seminar Series

Dr. Greg Cutter

Abstract

When I began studying the oceanic cycle of the metalloid element selenium, I had no idea that over 3 decades later I'd still find new features to surprise me, and I'm not the only one to find this element fascinating. In part, the selenium cycle's complexity is due to the existence of multiple oxidation states in the environment (-2, 0, +4, +6) and chemical forms within these oxidation states (inorganic and organic), but also its role in many biochemical processes; it is both essential and toxic depending on its concentration and chemical speciation. To fully discuss the selenium cycle would go on for many, many hours, so instead this talk will focus on two of the newest findings: how the biogeochemical cycle of selenium can be exploited as a paleo-redox and nutrient tracer, and anthropogenic perturbations on the oceanic selenium cycle (lead and mercury revisited). With respect to both of these topics, I will end my presentation by briefly discussing the new international GEOTRACES Program and how it can be used to examine the global biogeochemical cycling of trace elements like selenium (and the rest of the periodic table).