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Gagliardini O, Durand G, Zwinger T, Hindmarsh R C A, Le Meur E, . (2010). Coupling of ice-shelf melting and buttressing is a key process in ice-sheets dynamics
. Geophysical Research Letters, 37(14), 1–5.
Abstract: Increase in ice-shelf melting is generally presumed to have triggered recent coastal ice-sheet thinning. Using a full-Stokes finite element model which includes a proper description of the grounding line dynamics, we investigate the impact of melting below ice shelves. We argue that the influence of ice-shelf melting on the ice-sheet dynamics induces a complex response, and the first naive view that melting inevitably leads to loss of grounded ice is erroneous. We demonstrate that melting acts directly on the magnitude of the buttressing force by modifying both the area experiencing lateral resistance and the ice-shelf velocity, indicating that the decrease of back stress imposed by the ice-shelf is the prevailing cause of inland dynamical thinning. We further show that feedback from melting and buttressing forces can lead to nontrivial results, as an increase in the average melt rate may lead to inland ice thickening and grounding line advance. Citation: Gagliardini, O., G. Durand, T. Zwinger, R. C. A. Hindmarsh, and E. Le Meur (2010), Coupling of ice-shelf melting and buttressing is a key process in ice-sheets dynamics, Geophys. Res. Lett., 37, L14501, doi:10.1029/2010GL043334.
Keywords: glaciology, meteorology climatology,
Programme: 1053
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. (2009). A 4-decade record of elevation change of the Amery Ice Shelf, East Antarctica
. Journal of Geophysical Research, 114(F1), F01010–.
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Dommergue Aurelien, Larose Catherine, Fain Xavier, Clarisse Olivier, Foucher Delphine, Hintelmann Holger, Schneider Dominique, Ferrari Christophe P,. (2010). Environ. Sci. Technol., 44(3), 901–907.
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Preunkert S, Legrand M, Stricker P, Bulat S, Alekhina I, Petit J R, Hoffmann H, May B, Jourdain B, . (2010). Quantification of Dissolved Organic Carbon at Very Low Levels in Natural Ice Samples by a UV-Induced Oxidation Method
. Environ. Sci. Technol., 45(2), 673–678.
Abstract: The study of chemical impurities trapped in solid precipitation and accumulated in polar ice sheets and high-elevation, midlatitude cold glaciers over the last several hundreds of years provides a unique way to reconstruct our changing atmosphere from the preindustrial era to the present day. Numerous ice core studies of inorganic species have already evaluated the effects of growing anthropogenic emissions of SO2 or NOx on the chemical composition of the atmosphere in various regions of the world. While it was recently shown that organic species dominate the atmospheric aerosol mass, the contribution of anthropogenic emissions to their budget remains poorly understood. The study of organics in ice is at the infancy stage, and it still is difficult to draw a consistent picture of the organic content of polar ice from sparse available data. A UV oxidation method and IR quantification of CO2 was optimized to obtain measurements of dissolved organic carbon content as low as a few ppbC. Stringent working conditions were defined to prevent contamination during the cleaning of ice. Measurements in various ice cores corresponding to preindustrial times revealed dissolved organic carbon content of less than 10 ppbC in Antarctica and up to 75 ppbC in alpine ice.
Programme: 355
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Larose Catherine, Dommergue Aurelien, Marusczak Nicolas, Coves Jacques, Ferrari Christophe P, Schneider Dominique, . (2011). Bioavailable Mercury Cycling in Polar Snowpacks
. Environ. Sci. Technol., 45(6), 2150–2156.
Abstract: Polar regions are subject to contamination by mercury (Hg) transported from lower latitudes, severely impacting human and animal health. Atmospheric Mercury Depletion Events (AMDEs) are an episodic process by which Hg is transferred from the atmospheric reservoir to arctic snowpacks. The fate of Hg deposited during these events is the subject of numerous studies, but its speciation remains unclear, especially in terms of environmentally relevant forms such as bioavailable mercury (BioHg). Here, using a bacterial mer-lux biosensor, we report the fraction of newly deposited Hg at the surface and at the bottom of the snowpack that is bioavailable. Snow samples were collected over a two-month arctic field campaign in 2008. In surface snow, BioHg is related to atmospheric Hg deposition and snow fall events were shown to contribute to higher proportions of BioHg than AMDEs. Based on our data, AMDEs represent a potential source of 20 t.y?1 of BioHg, while wet and dry deposition pathways may provide 135?225 t.y?1 of BioHg to Arctic surfaces.
Programme: 399
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Castro Ludovic, Dommergue Aurelien, Larose Catherine, Ferrari Christophe, Maron Laurent, . (2011). A Theoretical Study of Abiotic Methylation Reactions of Gaseous Elemental Mercury by Halogen-Containing Molecules
. J. Phys. Chem. A, 115(22), 5602–5608.
Abstract: Methylation reactions of gaseous elementary mercury by halogen containing molecules such as halogenomethane species CH3X (with X = Cl, Br, and I) and the dimethylchlorinium ion CH3ClCH3+ were investigated at the density functional level. With CH3X, the reaction is predicted to be almost athermic and kinetically demanding for a thermal reaction. The reaction can proceed photochemically in the visible range; therefore sunlight may increase the reaction rate. These results compare well with the experimental data. Consecutive methylation of the CH3HgX products (with X = Cl, Br, and I) and subsequent formation of CH3HgCH3 were also studied. These reactions are predicted to be kinetically inaccessible and thermodynamically unfavorable. With CH3ClCH3+, the reaction is predicted to be athermic but kinetically easy. This is due to the suitability of the methyl transfer reagent. Geometrical and electronic data were systematically analyzed in order to rationalize the results.
Programme: 399
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. (2014). Spatial Ecotoxicology: Migratory Arctic Seabirds Are Exposed to Mercury Contamination While Overwintering in the Northwest Atlantic
. Environ. Sci. Technol., 48(19), 11560–11567.
Abstract: Arctic organisms are exposed to various levels of pollutants, among which mercury (Hg) has raised important environmental concerns. Previous studies examining Hg levels, trends, and effects on Arctic marine top predators have focused on the Arctic region. However, many of these top predators, such as seabirds, migrate to spend a large part of their life cycle far from the Arctic in areas where their exposure to contaminants is largely unknown. By combining biotelemetry and Hg and stable isotope analyses, we studied the seasonal Hg contamination of little auks (Alle alle, the most abundant Arctic seabird) in relation to their distribution and marine foraging habitat, as well as its potential impacts on bird reproduction. We show that little auks were ?3.5 times more contaminated when outside the breeding season, and that Hg that accumulated during this nonbreeding non-Arctic period was related to egg size the following season, with females having more Hg laying smaller eggs. Our results highlight that ecotoxicological studies should be expanded to yield a comprehensive understanding of contamination risks and associated threats to top predators over their entire annual cycle. Furthermore, we show that an important nonbreeding area located in the northwest Atlantic was associated with greater Hg contamination and demonstrate the utility of bird-borne miniaturized technology for evaluating the contamination of marine systems on large spatial scales.
Programme: 388
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. (2014). Endocrine and fitness correlates of long-chain perfluorinated carboxylates exposure in Arctic breeding black-legged kittiwakes.
. 0013-936X, 48(22), 13504–10.
Abstract: Increasing levels of poly- and perfluorinated alkyl substances (PFASs) have recently been described in Arctic biota. These emerging substances are of concern given their resistance to degradation and metabolization. Some studies have reported endocrine disrupting effects for some PFASs. However, there is a gap of knowledge on the potential relationships between PFASs and hormones mediating the life-history trade-off between reproduction and survival, such as glucocorticoids. The aims of this study were to (1) describe the concentrations of plasma perfluoroalkyl sulfonates and perfluoroalkyl carboxylates in Svalbard black-legged kittiwakes (Rissa tridactyla) in relation to gender and body-condition, (2) explore the relationships between PFASs and corticosterone (the major glucocorticoid in birds), and (3) assess the consequences of PFAS exposure for reproductive success. Perfluorononanoate was positively related to body-condition in male kittiwakes; perfluorotridecanoate and perfluorotetradecanoate to decreased baseline corticosterone in both sexes; and perfluorododecanoate was related to lower hatching success. These results underline the importance of considering each compound separately when investigating the hazardous effects of PFASs on wildlife.
Keywords: Animals, Arctic Regions, Breeding, Charadriiformes, Charadriiformes: blood, Corticosterone, Corticosterone: blood, Female, Fluorocarbons, Fluorocarbons: toxicity, Glucocorticoids, Glucocorticoids: blood, Hydrocarbons, Fluorinated, Hydrocarbons, Fluorinated: toxicity, Male, Reproduction, Reproduction: drug effects,
Programme: 330
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. (2014). Wandering albatrosses document latitudinal variations in the transfer of persistent organic pollutants and mercury to Southern Ocean predators.
. Environ. Sci. Technol., 48(24), 14746–55.
Abstract: Top marine predators are effective tools to monitor bioaccumulative contaminants in remote oceanic environments. Here, we used the wide-ranging wandering albatross Diomedea exulans to investigate potential geographical variations of contaminant transfer to predators in the Southern Ocean. Blood concentrations of 19 persistent organic pollutants and 14 trace elements were measured in a large number of individuals (N = 180) of known age, sex and breeding status from the subantarctic Crozet Islands. Wandering albatrosses were exposed to a wide range of contaminants, with notably high blood mercury concentrations. Contaminant burden was markedly influenced by latitudinal foraging habitats (inferred from blood δ(13)C values), with individuals feeding in warmer subtropical waters having lower concentrations of pesticides, but higher concentrations of mercury, than those feeding in colder subantarctic waters. Sexual differences in contaminant burden seemed to be driven by gender specialization in feeding habitats, rather than physiological characteristics, with females foraging further north than males. Other individual traits, such as adult age and reproductive status, had little effect on blood contaminant concentrations. Our study provides further evidence of the critical role of global distillation on organic contaminant exposure to Southern Ocean avian predators. In addition, we document an unexpected high transfer of mercury to predators in subtropical waters, which merits further investigation.
Keywords: Animals, Arsenic, Arsenic: blood, Birds, Birds: blood, Birds: physiology, Ecosystem, Environmental Monitoring, Female, Food Chain, Halogenated Diphenyl Ethers, Halogenated Diphenyl Ethers: blood, Hydrocarbons, Chlorinated, Hydrocarbons, Chlorinated: blood, Male, Metals, Heavy, Metals, Heavy: blood, Oceans and Seas, Reproduction, Water Pollutants, Chemical, Water Pollutants, Chemical: blood,
Programme: 109
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Grilli R, Marrocco N, Desbois T, Guillerm C, Triest J, Kerstel E, Romanini D, . (2014). Invited article: SUBGLACIOR: an optical analyzer embedded in an Antarctic ice probe for exploring the past climate.
. The Review of scientific instruments, 85(11), 111301.
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