HR: 1340h
AN: H53A-1205    [Abstracts]
TI: Complexation of Inorganic Mercury in Freshwaters: Spatial Variability and Ligand Sources
AU: * Black, F J
EM: black@etox.ucsc.edu
AF: University of California, Santa Cruz, 1156 High Street Department of Environmental Toxicology, Santa Cruz, CA 95064 United States
AU: Flegal, A
EM: flegal@etox.ucsc.edu
AF: University of California, Santa Cruz, 1156 High Street Department of Environmental Toxicology, Santa Cruz, CA 95064 United States
AB: The speciation, bioavailability, and toxicity of mercury in aquatic systems are substantially influenced by complexation with natural ligands. Wetlands, waste water treatment plants, and other sub-oxic environments serve as important sites for the methylation of inorganic mercury (Hg[II])to its more toxic form, monomethyl mercury (MMHg). These environments are also sources of sulfide, polysulfides, thiols, and other reduced sulfur ligands which can form strong complexes with Hg(II) and MMHg. This complexation can affect the biogeochemical cycling of mercury by altering its bioavailability, transport, and mineral phase dissolution rates. This project aims to better understand the role these unique reducing environments play in the aquatic chemistry of mercury in oxic receiving waters. A technique employing competitive ligand exchange followed by solid phase extraction (CLE-SPE) is being used to characterize the concentration and binding strengths of ligands in natural freshwaters which complex inorganic Hg(II) at environmentally relevant dissolved mercury levels. Sampling has been designed to evaluate the role of wetlands, seasonally anoxic lakes, and other reducing environments as potential sources of ligands. Their effects on the complexation of Hg(II) at downstream sites with elevated mercury levels are also investigated. The concentration, stability, and transport of these complexes, and their possible effects on the methylation and mobility of mercury, are being examined in various freshwater lakes and steams.
DE: 4807 Chemical speciation and complexation
DE: 1806 Chemistry of fresh water
DE: 1890 Wetlands
DE: 1030 Geochemical cycles (0330)
DE: 1065 Trace elements (3670)
SC: Hydrology [H]
MN: 2004 AGU Fall Meeting