title: Differentiated availability of geochemical mercury pools controls methylmercury levels in estuarine sediment and biota.
abstract: Neurotoxic methylmercury (MeHg) formed from inorganic divalent mercury (Hg(II)) accumulates in aquatic biota and remains at high levels worldwide. It is poorly understood to what extent different geochemical Hg pools contribute to these levels. Here we report quantitative data on MeHg formation and bioaccumulation, in mesocosm water-sediment model ecosystems, using five Hg(II) and MeHg isotope tracers simulating recent Hg inputs to the water phase and Hg stored in sediment as bound to natural organic matter or as metacinnabar. Calculations for an estuarine ecosystem suggest that the chemical speciation of Hg(II) solid/adsorbed phases control the sediment Hg pool's contribution to MeHg, but that input of MeHg from terrestrial and atmospheric sources bioaccumulates to a substantially greater extent than MeHg formed in situ in sediment. Our findings emphasize the importance of MeHg loadings from catchment runoff to MeHg content in estuarine biota and we suggest that this contribution has been underestimated.
authors.affiliation: 1] Department of Chemistry, Umeå University, SE-901 87 Umeå, Sweden [2] Umeå Marine Sciences Centre, Umeå University, SE-910 20 Hörnefors, Sweden.
authors.forename: Sofi
authors.initials: S
authors.lastname: Jonsson
authors.affiliation: Department of Forest Ecology and Management, Swedish University of Agricultural Sciences, SE-901 83 Umeå, Sweden.
authors.forename: Ulf
authors.initials: U
authors.lastname: Skyllberg
authors.affiliation: Department of Forest Ecology and Management, Swedish University of Agricultural Sciences, SE-901 83 Umeå, Sweden.
authors.forename: Mats B
authors.initials: MB
authors.lastname: Nilsson
authors.affiliation: Umeå Marine Sciences Centre, Umeå University, SE-910 20 Hörnefors, Sweden.
authors.forename: Erik
authors.initials: E
authors.lastname: Lundberg
authors.affiliation: 1] Umeå Marine Sciences Centre, Umeå University, SE-910 20 Hörnefors, Sweden [2] Department of Ecology and Environmental Science, Umeå University, SE-901 87 Umeå, Sweden.
authors.forename: Agneta
authors.initials: A
authors.lastname: Andersson
authors.affiliation: Department of Chemistry, Umeå University, SE-901 87 Umeå, Sweden.
authors.forename: Erik
authors.initials: E
authors.lastname: Björn
mesh_terms: D000327:Adsorption; D058448:Biota / Q000187:drug effects* / Q000502:physiology; D017753:Ecosystem; D004784:Environmental Monitoring; D063366:Estuaries; D019015:Geologic Sediments / Q000737:chemistry*; D008628:Mercury / Q000032:analysis / Q000737:chemistry* / Q000633:toxicity; D008767:Methylmercury Compounds / Q000032:analysis / Q000737:chemistry* / Q000633:toxicity; D013548:Sweden; D014874:Water Pollutants, Chemical / Q000032:analysis / Q000737:chemistry* / Q000633:toxicity
chemical_list: D008767:Methylmercury Compounds; D014874:Water Pollutants, Chemical; D008628:Mercury; C004925:methylmercuric chloride