Dr. Andrew Graham, Grinnell College

Host: Dr. Gundlach-Graham

Owing to significant atmospheric emissions and its moderately long residence time in the atmosphere, Hg is a globally distributed pollutant. Little is known about the fate of atmospherically derived Hg in Iowa’s terrestrial and aquatic ecosystems even though Iowa receives high wet deposition of Hg. Here, we report on initial results from a first study of Hg riverine fluxes in Iowa, measured for the Cedar River near its confluence with the Iowa River for the period 2016-2018. Complementary studies focused on groundwaters and wetlands within the river floodplain to shed light on the processes of Hg methylation, demethylation, and bioaccumulation. This talk will emphasize analytical approaches to characterizing Hg speciation and biogeochemical processes in environmental media, with special emphasis on the use of enriched stable isotope tracer experiments.

Andrew Graham is Associate Professor of Chemistry and Chair of Environmental Studies at Grinnell College in Grinnell Iowa. His research focuses on the biogeochemistry of trace elements and nutrients at scales ranging from the molecular to ecosystem-level. Andrew has a B.A. in Geology (Earlham College) and Ph.D. in Environmental Engineering (Johns Hopkins University). Prior to teaching at Grinnell, Andrew was a Smithsonian Institution postdoctoral fellow at the Smithsonian Environmental Research Center in Edgewater, Maryland.