Water Resources Research Act Program

Details for Project ID 2007ME148B

Using reactive thin-film membranes and Molecular Tools to determine mercury mobility and transformation in the Penobscot River estuary sediment, Maine

Institute: Maine
Year Established: 2007 Start Date: 2008-04-01 End Date: 2009-03-31
Total Federal Funds: $19,600 Total Non-Federal Funds: $41,250

Principal Investigators: Aria Amirbahman, Melinda Diehl

Project Summary: The inland and coastal waters in Maine have been subject to decades of anthropogenic mercury (Hg) loading. Consequently, aquatic biota have accumulated some of the highest Hg body burdens in the United States. Of particular concern is the bioavailability and geochemical cycling of Hg in estuaries which is controlled by both biotic and abiotic processes. Hg transformation and shifts in Hg mobility within estuaries occur rapidly under changing redox conditions driven by tides. Measuring Hg fluxes in estuaries is difficult due to redox sensitivity, high spatial heterogeneity, and the low concentrations at which Hg is present. We have developed a thin-film membrane that can increase the spatial and temporal resolution of Hg measurement in sediments. The membranes have been tested in the lab and show a high uptake capacity and fast uptake kinetics. We propose to deploy the membranes in the contaminated sediments of the Penobscot River estuary to measure Hg flux, and to provide quantitative information regarding the lability of the sediment Hg and methylmercury (MeHg) pools. In addition, molecular analyses will be conducted to characterize the microbial processes that lead to mobilization and transformation of Hg species. Combined, these two approaches provide mechanistic insight into the mobility and bioavailability of sediment Hg, two characteristics that affect Hg bioaccumulation. This will be a collaborative effort between the Department of Civil Engineering at the University of Maine and the Microbiology/ Molecular Ecology Team at the USGS that will contribute to future remediation and sustainable fisheries efforts.