title: Methylmercury speciation in the dissolved phase of a stratified lake using the diffusive gradient in thin film technique.
abstract: The diffusive gradient in thin film (DGT) technique was successfully used to monitor methylmercury (MeHg) speciation in the dissolved phase of a stratified boreal lake, Lake 658 of the Experimental Lakes Area (ELA) in Ontario, Canada. Water samples were conventionally analysed for MeHg, sulfides, and dissolved organic matter (DOM). MeHg accumulated by DGT devices was compared to MeHg concentration measured conventionally in water samples to establish MeHg speciation. In the epilimnion, MeHg was almost entirely bound to DOM. In the top of the hypolimnion an additional labile fraction was identified, and at the bottom of the lake a significant fraction of MeHg was potentially associated to colloidal material. As part of the METAALICUS project, isotope enriched inorganic mercury was applied to Lake 658 and its watershed for several years to establish the relationship between atmospheric Hg deposition and Hg in fish. Little or no difference in MeHg speciation in the dissolved phase was detected between ambient and spike MeHg.
authors.affiliation: Trent University, Department of Chemistry, 1600 West Bank Drive, Peterborough, Ontario K9J 7B8, Canada.
authors.forename: Olivier
authors.initials: O
authors.lastname: Clarisse
authors.forename: Delphine
authors.initials: D
authors.lastname: Foucher
authors.forename: Holger
authors.initials: H
authors.lastname: Hintelmann
mesh_terms: D005591:Chemical Fractionation; D002849:Chromatography, Gas; D004463:Ecology / Q000379:methods; D005618:Fresh Water / Q000737:chemistry*; D006812:Humic Substances; D008628:Mercury / Q000032:analysis; D008767:Methylmercury Compounds / Q000032:analysis*; D008956:Models, Chemical; D009864:Ontario; D053719:Tandem Mass Spectrometry; D013997:Time Factors; D014874:Water Pollutants, Chemical / Q000032:analysis*
chemical_list: D006812:Humic Substances; D008767:Methylmercury Compounds; D014874:Water Pollutants, Chemical; D008628:Mercury