title: Hg Stable Isotope Time Trend in Ringed Seals Registers Decreasing Sea Ice Cover in the Alaskan Arctic.
abstract: Decadal time trends of mercury (Hg) concentrations in Arctic biota suggest that anthropogenic Hg is not the single dominant factor modulating Hg exposure to Arctic wildlife. Here, we present Hg speciation (monomethyl-Hg) and stable isotopic composition (C, N, Hg) of 53 Alaskan ringed seal liver samples covering a period of 14 years (1988-2002). In vivo metabolic effects and foraging ecology explain most of the observed 1.6 ‰ variation in liver δ(202)Hg, but not Δ(199)Hg. Ringed seal habitat use and migration were the most likely factors explaining Δ(199)Hg variations. Average Δ(199)Hg in ringed seal liver samples from Barrow increased significantly from +0.38 ± 0.08‰ (±SE, n = 5) in 1988 to +0.59 ± 0.07‰ (±SE, n = 7) in 2002 (4.1 ± 1.2% per year, p < 0.001). Δ(199)Hg in marine biological tissues is thought to reflect marine Hg photochemistry before biouptake and bioaccumulation. A spatiotemporal analysis of sea ice cover that accounts for the habitat of ringed seals suggests that the observed increase in Δ(199)Hg may have been caused by the progressive summer sea ice disappearance between 1988 and 2002. While changes in seal liver Δ(199)Hg values suggests a mild sea ice control on marine MMHg breakdown, the effect is not large enough to induce measurable HgT changes in biota. This suggests that Hg trends in biota in the context of a warming Arctic are likely controlled by other processes.
authors.affiliation: †Observatoire Midi-Pyrénées, Laboratoire Géosciences Environnement Toulouse, CNRS/IRD/Université Paul Sabatier Toulouse 3, 14 avenue Edouard Belin, 31400 Toulouse, France.
authors.forename: Jérémy
authors.initials: J
authors.lastname: Masbou
authors.affiliation: †Observatoire Midi-Pyrénées, Laboratoire Géosciences Environnement Toulouse, CNRS/IRD/Université Paul Sabatier Toulouse 3, 14 avenue Edouard Belin, 31400 Toulouse, France.
authors.forename: David
authors.initials: D
authors.lastname: Point
authors.affiliation: †Observatoire Midi-Pyrénées, Laboratoire Géosciences Environnement Toulouse, CNRS/IRD/Université Paul Sabatier Toulouse 3, 14 avenue Edouard Belin, 31400 Toulouse, France.
authors.forename: Jeroen E
authors.initials: JE
authors.lastname: Sonke
authors.affiliation: †Observatoire Midi-Pyrénées, Laboratoire Géosciences Environnement Toulouse, CNRS/IRD/Université Paul Sabatier Toulouse 3, 14 avenue Edouard Belin, 31400 Toulouse, France.
authors.forename: Frédéric
authors.initials: F
authors.lastname: Frappart
authors.affiliation: ‡Laboratoire de Chimie Analytique Bio-Inorganique et Environnement, Institut Pluridisciplinaire de Recherche sur l'Environnement et les Matériaux, CNRS-UPPA-UMR-5254, Hélioparc, 2 Avenue du Président Pierre Angot, Pau, 64053, France.
authors.forename: Vincent
authors.initials: V
authors.lastname: Perrot
authors.affiliation: ‡Laboratoire de Chimie Analytique Bio-Inorganique et Environnement, Institut Pluridisciplinaire de Recherche sur l'Environnement et les Matériaux, CNRS-UPPA-UMR-5254, Hélioparc, 2 Avenue du Président Pierre Angot, Pau, 64053, France.
authors.forename: David
authors.initials: D
authors.lastname: Amouroux
authors.affiliation: §UMR Littoral, Environnement et Sociétés (LIENSs), UMR 7266 CNRS-Université de La Rochelle, Institut du Littoral et de l'Environnement, 2 rue Olympe de Gouges, 17000 La Rochelle, France.
authors.forename: Pierre
authors.initials: P
authors.lastname: Richard
authors.affiliation: ∥National Institute of Standards and Technology, Analytical Chemistry Division, Hollings Marine Laboratory, 331 Fort Johnson Road, Charleston, South Carolina 29412 United States.
authors.forename: Paul R
authors.initials: PR
authors.lastname: Becker
mesh_terms: D000413:Alaska; D000818:Animals; D001110:Arctic Regions; D017753:Ecosystem; D004784:Environmental Monitoring; D005843:Geography; D046448:Ice Cover; D007553:Isotope Labeling; D008099:Liver / Q000378:metabolism; D008629:Mercury Isotopes / Q000032:analysis; D046048:Seals, Earless / Q000378:metabolism*; D013997:Time Factors
chemical_list: D008629:Mercury Isotopes