Le cycle atmosphérique actuel du Hg est sans doute l’aspect le plus étudié du cycle global du Hg. Cependant, des incertitudes majeures persistent. L’importance des dépôts secs de Hg comparée aux dépôts humides reste incertaine, ainsi que les facteurs contrôlant les dépôts secs de Hg. L’ampleur de l’activité humaine sur le cycle du Hg, et en particulier sur les dépôts atmosphériques dans des écosystèmes reculés est toujours en cours de débat (facteur 3 ou 30 ?). L’impact (local, global ?) de l’activité minière coloniale (entre 1500 et 1900) n’est pas encore clarifié. L’objectif central de cette thèse de doctorat est de mieux contraindre les dépôts de Hg actuels et historiques sur les tourbières.
L’étape la plus importante sera de mieux caractériser les dépôts de Hg sur une tourbière. La plupart des études précédentes n’ont pas discuté les différents mécanismes de dépôt et se sont concentrés sur les variations temporelles. Le chapitre 1 de ce manuscrit décrit une expérience sur trois ans effectuée sur la tourbière du Pinet dans les Pyrénées françaises. L’objectif y est d’évaluer la contribution des dépôts de chaque espèce atmosphérique du Hg (GEM, GOM, PBM, dépôts humides) ainsi que la possibilité de réémission de Hg par photochimie.
En se basant sur les résultats du chapitre 1, on va comparer dans le chapitre 2 la composition en isotopes stables du Hg d’échantillons de tourbe provenant de différents sites en hémisphère nord. Deux tourbières pyrénéennes ont été étudiées dans ce cadre, ainsi que deux tourbières canadiennes (échantillons fournis par Peter Outridge et William Shotyk) et quatre tourbières norvégiennes (échantillons fournis par Eiliv Steinnes). Les résultats seront comparés à des données déjà publiées sur deux tourbières en Espagne et en Chine. En
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analysant des échantillons de différentes tourbières, l’objectif est d’observer des potentielles différences en en termes de séquestration du Hg par les tourbières.
Les deux tourbières pyrénéennes (Pinet et Estibère) ont fait l’objet d’une étude plus approfondie sur les dépôts et l’isotopie du Hg à haute résolution. Les variations historiques des dépôts de Hg, de concentration atmosphérique en GEM et de l’isotopie du Hg aux deux sites seront comparées et discutées dans le chapitre 3. Ce chapitre illustre le potentiel des isotopes du Hg dans les tourbières pour comprendre les mécanismes de dépôts et les sources de Hg dans l’atmosphère.
Jusqu’alors, cinquante-quatre tourbières ont été étudiées pour les dépôts historiques de Hg en hémisphère nord, dont la plupart en Europe. Ce dernier chapitre sera dédié à une reconsidération de ces études en se basant sur les conclusions des chapitres précédents, en étudiant les variations spatiales et temporelles. Les tendances temporelles en HgARs produites par les précédentes études seront compilées pour produire une reconstruction des variations de HgAR à l’échelle hémisphérique. L’impact de l’Homme sur l’accumulation du Hg dans les tourbières sera discuté en termes d’ampleur et de timing d’enrichissement en Hg dans l’atmosphère.
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REFERENCES
Allan, M. et al., 2013. Reconstructing historical atmospheric mercury deposition in Western Europe using: Misten peat bog cores, Belgium. Sci Total Environ, 442(0): 290-301. AMAP, 2013. Technical Background Report for the Global Mercury Assessment 2013. Arctic
Monitoringand Assessment Programme,.
Amos, H.M. et al., 2015. Observational and modeling constraints on global anthropogenic enrichment of mercury. Environ Sci Technol, 49(7): 4036-47.
Appelquist, H., Jensen, K.O., Sevel, T., Hammer, C., 1978. Mercury in the Greenland Ice Sheet. Nature, 273(5664): 657-659.
Bagnato, E. et al., 2014. Mercury fluxes from volcanic and geothermal sources: an update. Geological Society, London, Special Publications, 410(1): 263-285.
Bakir, F. et al., 1973. Methylmercury Poisoning in Iraq. Science, 181(4096): 230-241.
Beal, S.A., Osterberg, E.C., Zdanowicz, C.M., Fisher, D.A., 2015. Ice Core Perspective on Mercury Pollution during the Past 600 Years. Environ Sci Technol.
Benoit, J.M., Fitzgerald, W.F., Damman, A.W.H., 1998. The biogeochemistry of an ombrotrophic bog: Evaluation of use as an archive of atmospheric mercury deposition. Environmental Research, 78(2): 118-133.
Bergquist, B.A., Blum, J.D., 2007. Mass-Dependent and -Independent Fractionation of Hg Isotopes by Photoreduction in Aquatic Systems. Science, 318(5849): 417-420.
Biester, H., Bindler, R., Martinez-Cortizas, A., Engstrom, D.R., 2007. Modeling the past atmospheric deposition of mercury using natural archives. Environmental Science & Technology, 41(14): 4851-4860.
Bindler, R., 2006. Mired in the past — looking to the future: Geochemistry of peat and the analysis of past environmental changes. Global and Planetary Change, 53(4): 209-221. Bindler, R., Klarqvist, M., Klaminder, J., Förster, J., 2004. Does within-bog spatial variability of mercury and lead constrain reconstructions of absolute deposition rates from single peat records? The example of Store Mosse, Sweden. Global Biogeochemical Cycles, 18(3).
Blum, J.D., Sherman, L.S., Johnson, M.W., 2014. Mercury Isotopes in Earth and Environmental Sciences. Annual Review of Earth and Planetary Sciences, 42(1): 249- 269.
Boutron, C.F., Vandal, G.M., Fitzgerald, W.F., Ferrari, C.P., 1998. A forty year record of Mercury in central Greenland snow. Geophysical Research Letters, 25(17): 3315- 3318.
Chen, J.B., Hintelmann, H., Feng, X.B., Dimock, B., 2012. Unusual fractionation of both odd and even mercury isotopes in precipitation from Peterborough, ON, Canada. Geochimica Et Cosmochimica Acta, 90(0): 33-46.
Cobbett, F.D., Van Heyst, B.J., 2007. Measurements of GEM fluxes and atmospheric mercury concentrations (GEM, RGM and Hgp) from an agricultural field amended with biosolids in Southern Ont., Canada (October 2004–November 2004). Atmospheric Environment, 41(11): 2270-2282.
Das, R., Landing, W., Bizimis, M., Odom, L., Caffrey, J., 2015. Mass Independent Fractionation of Mercury Isotopes as Source Tracers in Sediments. Procedia Earth and Planetary Science, 13: 151-157.
32
Demers, J.D., Blum, J.D., Zak, D.R., 2013. Mercury isotopes in a forested ecosystem: Implications for air-surface exchange dynamics and the global mercury cycle. Global Biogeochemical Cycles, 27(1): 222-238.
Donovan, P.M., Blum, J.D., Yee, D., Gehrke, G.E., Singer, M.B., 2013. An isotopic record of mercury in San Francisco Bay sediment. Chemical Geology, 349–350(0): 87-98. EMEP, http://www.emep.int/. European Monitoring and Evaluation Programme.
Engstrom, D.R., Balogh, S.J., Swain, E.B., 2007. History of mercury inputs to Minnesota lakes: influences of watershed disturbance and localized atmospheric deposition. Limnology and Oceanography, 52(6): 2467-2483.
Engstrom, D.R. et al., 2014. Atmospheric Hg emissions from preindustrial gold and silver extraction in the Americas: a reevaluation from lake-sediment archives. Environ Sci Technol, 48(12): 6533-43.
Enrico, M., Le Roux, G., Heimbürger, L.E., Sonke, J., in prep. A synthesis of past atmospheric Hg deposition based on peat records. Science of The Total Environment. Ericksen, J.A. et al., 2003. Accumulation of atmospheric mercury in forest foliage.
Atmospheric Environment, 37(12): 1613-1622.
Estrade, N., Carignan, J., Sonke, J.E., Donard, O.F.X., 2009. Mercury isotope fractionation during liquid-vapor evaporation experiments. Geochimica Et Cosmochimica Acta, 73(10): 2693-2711.
Fain, X. et al., 2009. Polar firn air reveals large-scale impact of anthropogenic mercury emissions during the 1970s. Proc Natl Acad Sci U S A, 106(38): 16114-9.
Fang, F., Wang, Q., Li, J., 2004. Urban environmental mercury in Changchun, a metropolitan city in Northeastern China: source, cycle, and fate. Science of The Total Environment, 330(1–3): 159-170.
Fitzgerald, W.F., Engstrom, D.R., Mason, R.P., Nater, E.A., 1998. The case for atmospheric mercury contamination in remote areas. Environmental Science & Technology, 32(1): 1-7.
Fu, X., Feng, X., Sommar, J., Wang, S., 2012. A review of studies on atmospheric mercury in China. Science of The Total Environment, 421–422: 73-81.
Fu, X. et al., 2010a. Elevated atmospheric deposition and dynamics of mercury in a remote upland forest of southwestern China. Environmental Pollution, 158(6): 2324-2333. Fu, X. et al., 2008. Total particulate and reactive gaseous mercury in ambient air on the
eastern slope of the Mt. Gongga area, China. Applied Geochemistry, 23(3): 408-418. Fu, X.W. et al., 2010b. Atmospheric gaseous elemental mercury (GEM) concentrations and
mercury depositions at a high-altitude mountain peak in south China. Atmos. Chem. Phys., 10(5): 2425-2437.
Gay, D.A. et al., 2013. The Atmospheric Mercury Network: measurement and initial examination of an ongoing atmospheric mercury record across North America. Atmospheric Chemistry and Physics, 13(22): 11339-11349.
Ghosh, S., Schauble, E.A., Lacrampe Couloume, G., Blum, J.D., Bergquist, B.A., 2012. Estimation of nuclear volume dependent fractionation of mercury isotopes in equilibrium liquid–vapor evaporation experiments. Chemical Geology(0).
Ghosh, S., Xu, Y.F., Humayun, M., Odom, L., 2008. Mass-independent fractionation of mercury isotopes in the environment. Geochemistry Geophysics Geosystems, 9. Gratz, L.E., Keeler, G.J., Blum, J.D., Sherman, L.S., 2010. Isotopic composition and
fractionation of mercury in Great Lakes precipitation and ambient air. Environ Sci Technol, 44(20): 7764-70.
33
Graydon, J.A., St. Louis, V.L., Lindberg, S.E., Hintelmann, H., Krabbenhoft, D.P., 2006. Investigation of Mercury Exchange between Forest Canopy Vegetation and the Atmosphere Using a New Dynamic Chamber†. Environmental Science & Technology, 40(15): 4680-4688.
Gustin, M.S., 2011. Exchange of Mercury between the Atmosphere and Terrestrial Ecosystems, Environmental Chemistry and Toxicology of Mercury. John Wiley & Sons, Inc., pp. 423-451.
Hansson, S.V., Kaste, J.M., Olid, C., Bindler, R., 2014. Incorporation of radiometric tracers in peat and implications for estimating accumulation rates. Sci Total Environ, 493(0): 170-7.
Harada, M., 1995. Minamata Disease: Methylmercury Poisoning in Japan Caused by Environmental Pollution. Critical Reviews in Toxicology, 25(1): 1-24.
Hines, N.A., Brezonik, P.L., 2007. Mercury Inputs and Outputs at a Small Lake in Northern Minnesota. Biogeochemistry, 84(3): 265-284.
Holmes, C.D. et al., 2010. Global atmospheric model for mercury including oxidation by bromine atoms. Atmos. Chem. Phys., 10(24): 12037-12057.
Horowitz, H.M., Jacob, D.J., Amos, H.M., Streets, D.G., Sunderland, E.M., 2014. Historical Mercury releases from commercial products: global environmental implications. Environ Sci Technol, 48(17): 10242-50.
Hudson, R.J.M., Gherini, S.A., Fitzgerald, W.F., Porcella, D.B., 1995. Anthropogenic influences on the global mercury cycle: A model-based analysis. Water, Air, and Soil Pollution, 80(1-4): 265-272.
Lamborg, C.H. et al., 2002. Modern and historic atmospheric mercury fluxes in both hemispheres: Global and regional mercury cycling implications. Global Biogeochemical Cycles, 16(4): 1104.
Lamborg, C.H. et al., 2014. A global ocean inventory of anthropogenic mercury based on water column measurements. Nature, 512(7512): 65-68.
Lindberg, S. et al., 2007. A synthesis of progress and uncertainties in attributing the sources of mercury in deposition. Ambio, 36(1): 19-32.
Lindberg, S.E., Hanson, P.J., Meyers, T.P., Kim, K.H., 1998. Air/surface exchange of mercury vapor over forests—the need for a reassessment of continental biogenic emissions. Atmospheric Environment, 32(5): 895-908.
Lorey, P., Driscoll, C.T., 1999. Historical Trends of Mercury Deposition in Adirondack Lakes. Environmental Science & Technology, 33(5): 718-722.
Martínez Cortizas, A., Peiteado Varela, E., Bindler, R., Biester, H., Cheburkin, A., 2012. Reconstructing historical Pb and Hg pollution in NW Spain using multiple cores from the Chao de Lamoso bog (Xistral Mountains). Geochimica Et Cosmochimica Acta, 82(0): 68-78.
Mead, C., Lyons, J.R., Johnson, T.M., Anbar, A.D., 2013. Unique Hg Stable Isotope Signatures of Compact Fluorescent Lamp-Sourced Hg. Environmental Science & Technology, 47(6): 2542-2547.
Mergler, D. et al., 2007. Methylmercury exposure and health effects in humans: a worldwide concern. Ambio, 36(1): 3-11.
Muntean, M. et al., 2014. Trend analysis from 1970 to 2008 and model evaluation of EDGARv4 global gridded anthropogenic mercury emissions. Science of The Total Environment, 494–495: 337-350.
34
Outridge, P.M., Sanei, H., 2010. Does organic matter degradation affect the reconstruction of pre-industrial atmospheric mercury deposition rates from peat cores? — A test of the hypothesis using a permafrost peat deposit in northern Canada. International Journal of Coal Geology, 83(1): 73-81.
Pirrone, N. et al., 1998. Historical atmospheric mercury emissions and depositions in North America compared to mercury accumulations in sedimentary records. Atmospheric Environment, 32(5): 929-940.
Poissant, L., Pilote, M., Xu, X., Zhang, H., Beauvais, C., 2004. Atmospheric mercury speciation and deposition in the Bay St. François wetlands. Journal of Geophysical Research: Atmospheres, 109(D11): n/a-n/a.
Rafaj, P., Bertok, I., Cofala, J., Schöpp, W., 2013. Scenarios of global mercury emissions from anthropogenic sources. Atmospheric Environment, 79: 472-479.
Risch, M.R., DeWild, J.F., Krabbenhoft, D.P., Kolka, R.K., Zhang, L., 2012. Litterfall mercury dry deposition in the eastern USA. Environmental Pollution, 161: 284-290. Rolison, J.M., Landing, W.M., Luke, W., Cohen, M., Salters, V.J.M., 2013. Isotopic
composition of species-specific atmospheric Hg in a coastal environment. Chemical Geology, 336(0): 37-49.
Roos-Barraclough, F., Shotyk, W., 2003. Millennial-Scale Records of Atmospheric Mercury Deposition Obtained from Ombrotrophic and Minerotrophic Peatlands in the Swiss Jura Mountains. Environmental Science & Technology, 37(2): 235-244.
Rydberg, J. et al., 2010. Importance of vegetation type for mercury sequestration in the northern Swedish mire, Rodmossamyran. Geochimica Et Cosmochimica Acta, 74(24): 7116-7126.
Rydberg, J., Rösch, M., Heinz, E., Biester, H., 2015. Influence of catchment vegetation on mercury accumulation in lake sediments from a long-term perspective. Science of The Total Environment, 538: 896-904.
Sakata, M., Marumoto, K., 2005. Wet and dry deposition fluxes of mercury in Japan. Atmospheric Environment, 39(17): 3139-3146.
Schuster, P.F. et al., 2002. Atmospheric mercury deposition during the last 270 years: A glacial ice core record of natural and anthropogenic sources. Environmental Science & Technology, 36(11): 2303-2310.
Sherman, L.S. et al., 2010. Mass-independent fractionation of mercury isotopes in Arctic snow driven by sunlight. Nature Geoscience, 3(3): 173-177.
Shi, W. et al., 2011. High-precision measurement of mercury isotope ratios of atmospheric deposition over the past 150 years recorded in a peat core taken from Hongyuan, Sichuan Province, China. Chinese Science Bulletin, 56(9): 877-882.
Smith, R.S. et al., 2014. Small-scale studies of roasted ore waste reveal extreme ranges of stable mercury isotope signatures. Geochimica Et Cosmochimica Acta, 137(0): 1-17. Sonke, J.E., 2011. A global model of mass independent mercury stable isotope fractionation.
Geochimica Et Cosmochimica Acta, In Press, Accepted Manuscript.
Southworth, G. et al., 2007. Evasion of added isotopic mercury from a northern temperate lake. Environmental Toxicology and Chemistry, 26(1): 53-60.
Streets, D.G. et al., 2011. All-time releases of mercury to the atmosphere from human activities. Environ Sci Technol, 45(24): 10485-91.
Strode, S., Jaeglé, L., Selin, N.E., 2009. Impact of mercury emissions from historic gold and silver mining: Global modeling. Atmospheric Environment, 43(12): 2012-2017.
35
Štrok, M., Baya, P.A., Hintelmann, H., 2015. The mercury isotope composition of Arctic coastal seawater. Comptes Rendus Geoscience(0).
Sun, R. et al., 2014. Mercury stable isotope signatures of world coal deposits and historical coal combustion emissions. Environ Sci Technol, 48(13): 7660-8.
Teixeira, D.C., Montezuma, R.C., Oliveira, R.R., Silva-Filho, E.V., 2012. Litterfall mercury deposition in Atlantic forest ecosystem from SE – Brazil. Environmental Pollution, 164: 11-15.
Thiemens, M.H., Heidenreich, J.E., 1983. The Mass-Independent Fractionation of Oxygen: A Novel Isotope Effect and Its Possible Cosmochemical Implications. Science, 219(4588): 1073-1075.
Vandal, G.M., Fitzgerald, W.F., Boutron, C.F., Candelone, J.-P., 1993. Variations in mercury deposition to Antarctica over the past 34,000 years. Nature, 362(6421): 621-623. Wan, Q. et al., 2009. Atmospheric mercury in Changbai Mountain area, northeastern China II.
The distribution of reactive gaseous mercury and particulate mercury and mercury deposition fluxes. Environmental Research, 109(6): 721-727.
Wang, Z. et al., 2015. Mass-dependent and mass-independent fractionation of mercury isotopes in precipitation from Guiyang, SW China. Comptes Rendus Geoscience(0). Wang, Z., Zhang, X., Xiao, J., Zhijia, C., Yu, P., 2009. Mercury fluxes and pools in three
subtropical forested catchments, southwest China. Environmental Pollution, 157(3): 801-808.
Wiederhold, J.G., 2015. Metal Stable Isotope Signatures as Tracers in Environmental Geochemistry. Environmental Science & Technology, 49(5): 2606-2624.
Yin, R., Feng, X., Li, X., Yu, B., Du, B., 2014. Trends and advances in mercury stable isotopes as a geochemical tracer. Trends in Environmental Analytical Chemistry, 2(0): 1-10.
Zaccone, C. et al., 2009. Comparison of Hg concentrations in ombrotrophic peat and corresponding humic acids, and implications for the use of bogs as archives of atmospheric Hg deposition. Geoderma, 148(3-4): 399-404.
Zhang, L.M., Wright, L.P., Blanchard, P., 2009. A review of current knowledge concerning dry deposition of atmospheric mercury. Atmospheric Environment, 43(37): 5853- 5864.
Zhang, Y., Jaeglé, L., Thompson, L., Streets, D.G., 2014. Six centuries of changing oceanic mercury. Global Biogeochemical Cycles, 28(11): 2014GB004939.
Zheng, W., Hintelmann, H., 2010a. Isotope fractionation of mercury during its photochemical reduction by low-molecular-weight organic compounds. J Phys Chem A, 114(12): 4246-53.
Zheng, W., Hintelmann, H., 2010b. Nuclear field shift effect in isotope fractionation of mercury during abiotic reduction in the absence of light. J Phys Chem A, 114(12): 4238-45.
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