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TitleAre methylmercury concentrations in the wetlands of Kejimkujik National Park, Nova Scotia, Canada dependent on geology?
AuthorSiciliano, S D; Sangster, A; Daughney, C J; Loseto, L; Germida, J J; Rencz, A N; O'Driscoll, N J; Lean, D R S
SourceJournal of Environmental Quality vol. 32, issue 6, 2003 p. 2085-2094,
Alt SeriesGeological Survey of Canada, Contribution Series 2002153
ProvinceNova Scotia
Lat/Long WENS -65.4567 -65.1483 44.4803 44.2647
Subjectsenvironmental geology; geochemistry; mercury; ecosystems; bedrock geology; wetlands; heavy metals contamination; black shales; soils; soil geochemistry; swamps; sulphate; methylmercury; ethylmercury
ProgramToxic Substance Research Initiave - Project #124 - Multi-Disciplinary Study of Metal Cycling, Primarily Hg, in Aquatic and Terrestrial Environments
ProgramNSERC Natural Sciences and Engineering Research Council of Canada
LinksAbstract - Résumé
AbstractIn the relatively pristine ecosystem in Kejimkujik Park, Nova Scotia, methylmercury (MeHg) concentrations in loons, Gavia immer, are among the highest recorded anywhere in the world. This study investigated the influence of bedrock lithology on MeHg concentrations in wetlands. Twenty-five different wetland field sites were sampled over four different bedrock lithologies; Kejimkujik monzogranite, black sulfidic slate, gray slate, and greywacke. Soil samples were analyzed for ethylmercury (EtHg), MeHg, total Hg, acid-volatile sulfides (AVS), organic matter, and water content as well as the biological parameters, mercury methyltransferase (HgMT) activity, sulfate reduction rates, fatty acid methyl ester (FAME) composition, and acidity. Methylmercury concentrations in the wetlands were highly dependent (P < 0.08) on lithology with no significant difference between bogs, fens, and swamps . Methylmercury concentrations in wetland soils developed on Kejimkujik monzogranite averaged 900 ng kg-1 compared with only 300 ng kg-1 in wetland soils developed on black sulfidic slate. Fatty acid methyl ester composition was also lithologically dependent (P < 0.001) with biomarkers for Desulfobulbus spp. discriminating between sites containing high and low MeHg concentrations. Levels of MeHg in wetlands were predicted mainly (41% of the sum of squares) by HgMT activity that differed (P < 0.009) between wetlands, with activity in bogs almost three times that present in swamps. Wetland MeHg concentrations are highly dependent on the lithology on which they have developed for largely biological reasons.