title: Relationship of sediment redox conditions to methyl mercury in surface sediment of Louisiana Lakes.
abstract: Surface sediment from three Louisiana Lakes containing overlying water layer spiked with 2 microg/g (2 ppm) mercury were incubated under oxygenated (air) and nonoxygenated (N2) conditions for determining the impact of oxygen status of overlying water on methylation of Hg in surface sediment from these lakes. The added mercury resulted in a greater than ten fold increase in methyl mercury (MeHg) as compared to native concentration of MeHg. The increase in methyl Hg production was less in sediment in which overlying water was exposed to oxygen rather than nitrogen. Results suggest that methyl Hg production would be less in lakes containing an oxygenated water column. In parallel microcosm studies without added mercury. MeHg decreased in sediment when redox potential of sediment suspension was increased from -200mV to +50mV. Results of these studies demonstrate the importance of oxygenation or redox condition of surface sediment on mercury methylation and demethylation. Sediment conditions, which either reduce methylation or enhance demethylation in surface sediment, will limit the bioavailability of MeHg to the aquatic environment.
authors.affiliation: Wetlands Biogeochemistry Institute, School of the Coast and Environment Louisiana State University, Baton Rouge, Louisiana 70803-7511, USA. rdelaune@aol.com
authors.forename: R D
authors.initials: RD
authors.lastname: DeLaune
authors.forename: A
authors.initials: A
authors.lastname: Jugsujinda
authors.forename: I
authors.initials: I
authors.lastname: Devai
authors.forename: W H
authors.initials: WH
authors.lastname: Patrick
mesh_terms: D004784:Environmental Monitoring; D019015:Geologic Sediments / Q000737:chemistry*; D008145:Louisiana; D008628:Mercury / Q000737:chemistry; D008745:Methylation; D008767:Methylmercury Compounds / Q000032:analysis* / Q000737:chemistry*; D010084:Oxidation-Reduction; D014874:Water Pollutants, Chemical / Q000032:analysis*; D014881:Water Supply
chemical_list: D008767:Methylmercury Compounds; D014874:Water Pollutants, Chemical; D008628:Mercury