ACP Atmospheric Chemistry and Physics ACP 1680-7324 Copernicus GmbH Göttingen, Germany 10.5194/acp-12-9251-2012 How relevant is the deposition of mercury onto snowpacks? – Part 2: A modeling study Durnford D. 1 Dastoor A. 2 Ryzhkov A. 3 Poissant L. 4 Pilote M. 5 Figueras-Nieto D. 2 Independent researcher, 3031 Cedar Avenue, Montreal, QC, H3Y 1Y8, Canada Air Quality Research Division, Environment Canada, 2121 TransCanada Highway, Dorval, QC, H9P 1J3, Canada Independent researcher, 4998 Maisonneuve West, Westmount, QC, H3Z 1N2, Canada Atmospheric Toxic Processes Section, Environment Canada, 105 McGill St., Montreal, QC, H2Y 2E7, Canada Fluvial Ecosystem Research Section, Environment Canada, 105 McGill St., Montreal, QC, H2Y 2E7, Canada 11 10 2012 12 19 9251 9274 This is an open-access article ditributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. This article is available from http://www.atmos-chem-phys.net/12/9251/2012/acp-12-9251-2012.html The full text article is available as a PDF file from http://www.atmos-chem-phys.net/12/9251/2012/acp-12-9251-2012.pdf

An unknown fraction of mercury that is deposited onto snowpacks is revolatilized to the atmosphere. Determining the revolatilized fraction is important since mercury that enters the snowpack meltwater may be converted to highly toxic bioaccumulating methylmercury. In this study, we present a new dynamic physically-based snowpack/meltwater model for mercury that is suitable for large-scale atmospheric models for mercury. It represents the primary physical and chemical processes that determine the fate of mercury deposited onto snowpacks. The snowpack/meltwater model was implemented in Environment Canada's atmospheric mercury model GRAHM. For the first time, observed snowpack-related mercury concentrations are used to evaluate and constrain an atmospheric mercury model. We find that simulated concentrations of mercury in both snowpacks and the atmosphere's surface layer agree closely with observations. The simulated concentration of mercury in both in the top 30 cm and the top 150 cm of the snowpack, averaged over 2005–2009, is predominantly below 6 ng L<sup>−1</sup> over land south of 66.5&deg; N but exceeds 18 ng L<sup>&minus;1</sup> over sea ice in extensive areas of the Arctic Ocean and Hudson Bay. The average simulated concentration of mercury in snowpack meltwater runoff tends to be higher on the Russian/European side (>20 ng L<sup>−1</sup>) of the Arctic Ocean than on the Canadian side (<10 ng L<sup>−1</sup>). The correlation coefficient between observed and simulated monthly mean atmospheric surface-level gaseous elemental mercury (GEM) concentrations increased significantly with the inclusion of the new snowpack/meltwater model at two of the three stations (midlatitude, subarctic) studied and remained constant at the third (arctic). Oceanic emissions are postulated to produce the observed summertime maximum in concentrations of surface-level atmospheric GEM at Alert in the Canadian Arctic and to generate the summertime volatility observed in these concentrations at both Alert and Kuujjuarapik on subarctic Hudson Bay, Canada. We find that the fraction of deposited mercury that is revolatilized from snowpacks increases with latitude from 39% between 30 and 45&deg; N, to 57% from 45 to 60&deg; N, 67% from 60 to 66.5&deg; N, and 75% polewards of 66.5&deg; N on an annual basis. Combining this latitudinal gradient with the latitudinally increasing coverage of snowpacks causes yearly net deposition as a fraction of gross deposition to decrease from 98% between 30 and 45&deg; N to 89% between 45 and 60&deg; N, 73% between 60 and 66.5&deg; N, and 44% within the Arctic Circle. The yearly net deposition and net accumulation of mercury at the surface within the Arctic Circle north of 66.5&deg; N are estimated at 153 and 117 Mg, respectively. We calculate that 58 and 50 Mg of mercury are deposited annually to the Arctic Ocean directly and indirectly via melting snowpacks, respectively. For terrestrial surfaces within the Arctic Circle, we find that 29 and 16 Mg of mercury are deposited annually directly and indirectly via melting snowpacks, respectively. Within the Arctic Circle, multi-season snowpacks on land and over sea ice gained, on average, an estimated 0.1 and 0.4 Mg yr<sup>−1</sup> mercury, respectively, from 2000–2005. The developed snowpack/meltwater model can be used for investigating the impact of climate change on the snowpack/atmosphere exchange of mercury.

 References Abbatt, J. P. D.: Interactions of atmospheric trace gases with ice surfaces: Adsorption and reaction, Chem. Rev., 103, 4783–4800, 2003. Albert, M. R. and Shultz, E. F.: Snow and firn properties and air-snow transport processes at Summit, Greenland, Atmos. Environ., 36, 2789–2797, 2002. Allan, C. J., Heyes, A., Roulet, N. T., St. Louis, V. L., and Rudd, J. W. M.: Spatial and temporal dynamics of mercury in Precambrian Shield upland runoff, Biogeochemistry, 52, 13–40, 2001. AMAP: Arctic Pollution 2011, Arctic Monitoring and Assessment Programme (AMAP), Oslo, Norway, 38 pp., 2011. Anderson, P. S., Neff, W. D.: Boundary layer physics over snow and ice, Atmos. Chem. Phys., 8, 3563–3582, http://dx.doi.org/10.5194/acp-8-3563-2008doi:10.5194/acp-8-3563-2008, 2008. Andersson, M. E., Gårdfeldt, K., Wängberg, I., and Strömberg, D.: Determination of Henry's law constant for elemental mercury, Chemosphere, 73, 587–592, http://dx.doi.org/10.1016/j.chemosphere.2008.05.067doi:10.1016/j.chemosphere.2008.05.067, 2008a. Andersson, M. E., Sommar, J., Gårdfeldt, K., and Lindqvist, O.: Enhanced concentrations of dissolved gaseous mercury in the surface waters of the Arctic Ocean, Mar. Chem., 110, 190–194, 2008b. Ariya, P. A., Khazilov, A., and Gidas, A.: Reactions of gaseous mercury with atomic and molecular halogens: Kinetics, product studies, and atmospheric implications, J. Phys. Chem. A., 106, 7310–7320, 2002. Ariya, P. A., Dastoor, A. P., Amyot, M., Schroeder, W. H., Barrie, L., Anlauf, K., Raofie, F., Ryzhkov, A., Davignon, D., Lalonde, J., and Steffen, A.: The Arctic: a sink for mercury, Tellus, Ser. B, 56, 397–403, 2004. Bales, R. C., Davis, R. E., and Stanley, D. A.: Ion elution through shallow homogeneous snow, Water Resour. Res., 25, 1869–1877, 1989. Bales, R. C., Sommerfeld, R. A., Kebler, D. G.: Ionic tracer movement through a Wyoming snowpack, Atmos. Environ., 24, 2749–2758, 1990. Balogh, S. J., Meyer, M. L., Hansen, N. C., Moncrief, J. F., and Gupta, S. C.: Transport of mercury from a cultivated field during snowmelt, J. Environ. Qual., 29, 871–874, 2000. Bargagli, R., Agnorelli, C., Borghini, F., and Monaci, F.: Enhanced deposition and bioaccumulation of mercury in Antarctic terrestrial ecosystems facing a coastal polynya, Environ. Sci. Technol., 39, 8150–8155, 2005. Bartels-Rausch, T., Huthwelker, T., Jöri, M., Gäggeler, H. W., Ammann, M.: Interaction of gaseous elemental mercury with snow surfaces: laboratory investigation, Environ. Res. Lett., 3, 045009, http://dx.doi.org/10.1088/1748-9326/3/4/045009doi:10.1088/1748-9326/3/4/045009, 2008. Bartels-Rausch, T., Krysztofiak, G., Bernhard, A., Schläppi, M., Schwikowski, M., and Ammann, M.: Photoinduced reduction of divalent mercury in ice by organic matter, Chemosphere, 82, 199–203, 2011. Berg, T., Sekkesæter, S., Steinnes, E., Valdal, A.-K., and Wibetoe, G.: Springtime depletion of mercury in the European Arctic as observed at Svalbard, Sci. Total Environ., 304, 43–51, 2003. Bishop, K., Lee, Y.-H., Pettersson, C., and Allard, B.: Methylmercury output from the Svartberget catchment in Northern Sweden during spring flood, Water Air Soil Poll., 80, 445–454, 1995. Blanchard, P., Froude, F. A., Martin, J. B., Dryfhout-Clark, H., and Woods, J. T.: Four years of continuous total gaseous mercury (TGM) measurements at sites in Ontario, Canada, Atmos. Environ., 36, 3735–3743, 2002. Boutron, C. F., Vandal, G. M., Fitzgerald, W. F., and Ferrari, C. P.: A forty year record of mercury in central Greenland snow, Geophys. Res. Lett., 25, 3315–3318, 1998. Brooks, S. B., Saiz-Lopez, A., Skov, H., Lindberg, S. E., Plane, J. M. C., and Goodsite, M. E.: The mass balance of mercury in the springtime arctic environment, Geophys. Res. Lett., 33, L13812, http://dx.doi.org/10.1029/2005GL025525doi:10.1029/2005GL025525, 2006. Brooks, S., Arimoto, R., Lindberg, S., and Southworth, G.: Antarctic polar plateau snow surface conversion of deposited oxidized mercury to gaseous elemental mercury with fractional long-term burial, Atmos. Environ., 42, 2877–2884, 2008a. Brooks, S., Lindberg, S., Southworth, G., and Arimoto, R.: Springtime atmospheric mercury speciation in the McMurdo, Antarctica coastal region, Atmos. Environ., 42, 2885–2893, 2008b. Christensen, J. H., Brandt, J., Frohn, L. M., Skov, H.: Modelling of mercury in the Arctic with the Danish Eulerian Hemispheric Model, Atmos. Chem. Phys., 4, 2251–2257, http://dx.doi.org/10.5194/acp-4-2251-2004doi:10.5194/acp-4-2251-2004, 2004. Cobbett, F. D., Steffen, A., Lawson, G., and Van Heyst, B. J.: GEM fluxes and atmospheric mercury concentrations (GEM, RGM and Hg$^p$) in the Canadian Arctic at Alert, Nunavut, Canada (February–June 2005), Atmos. Environ., 41, 6527–6543, 2007. Cole, A. S. and Steffen, A.: Trends in long-term gaseous mercury observations in the Arctic and effects of temperature and other atmospheric conditions, Atmos. Chem. Phys., 10, 4661–4772, http://dx.doi.org/10.5194/acp-10-4661-2010doi:10.5194/acp-10-4661-2010, 2010. Constant, P., Poissant, L., Villemur, R., Yumvihoze, E., and Lean, D.: Fate of inorganic mercury and methyl mercury within the snow cover in the low arctic tundra on the shore of Hudson Bay (Québec, Canada), J. Geophys. Res., 112, D08309, http://dx.doi.org/10.1029/2006JD007961doi:10.1029/2006JD007961, 2007. Côté, J., Desmarais, J.-G., Gravel, S., Méthot, A., Patoine, A., Roch, M., and Staniforth, A.: The operational CMC-MRB Global Environmental Multiscale (GEM) Model: Part II – Results, Mon. Weather Rev., 126, 1397–1418, 1998a. Côté, J., Gravel, S., Méthot, A., Patoine, A., Roch, M., and Staniforth, A.: The operational CMC-MRB Global Environmental Multiscale (GEM) Model: Part I – Design considerations and formulation, Mon. Wea. Rev., 126, 1373–1395, 1998b. Cozic, J., Verheggen, B., Weingartner, E., Crosier, J., Bower, K. N., Flynn, M., Coe, H., Henning, S., Steinbacher, M., Henne, S., Collaud Coen, M., Petzold, A., Baltensperger, U.: Chemical composition of free tropospheric aerosol for PM1 and coarse mode at the high alpine site Jungfraujoch, Atmos. Chem. Phys., 8, 407–423, http://dx.doi.org/10.5194/acp-8-407-2008doi:10.5194/acp-8-407-2008, 2008. Dastoor, A. P., Davignon, D., Theys, N., Van Roozendael, M., Steffen, A., and Ariya, P. A.: Modeling dynamic exchange of gaseous elemental mercury at polar sunrise, Environ. Sci. Technol., 42, 5183–5188, http://dx.doi.org/10.1021/es800291wdoi:10.1021/es800291w, 2008. Domine, F., Albert, M., Huthwelker, T., Jacobi, H.-W., Kokhanovsky, A. A., Lehning, M., Picard, G., and Simpson, W. R.: Snow physics as relevant to snow photochemistry, Atmos. Chem. Phys., 8, 171–208, http://dx.doi.org/10.5194/acp-8-171-2008doi:10.5194/acp-8-171-2008, 2008. Dommergue, A., Ferrari, C. P., Gauchard, P.-A., and Boutron, C. F.: The fate of mercury species in a sub-arctic snowpack during snowmelt, Geophys. Res. Lett., 30, 1621, http://dx.doi.org/10.1029/2003GL017308doi:10.1029/2003GL017308, 2003. Dommergue, A., Bahlmann, E., Ebinghaus, R., Ferrari, C., and Boutron, C.: Laboratory simulation of Hg$^0$ emissions from a snowpack, Anal. Bioanal. Chem., 388, 319–327, 2007. Dommergue, A., Larose, C., Faïn, X., Clarisse, O., Foucher, D., Hintelmann, H., Schneider, D., and Ferrari, C. P.: Deposition of mercury species in the Ny-Ålesund area (79° N) and their transfer during snowmelt, Environ. Sci. Technol., 44, 901–907, http://dx.doi.org/10.1021/es902579mdoi:10.1021/es902579m, 2010. Donohoue, D. L., Bauer, D., and Hynes, A. J.: Temperature and pressure dependent rate coefficients for the reaction of Hg with Cl and the reaction of Cl with Cl: A pulsed laser photolysis-pulsed laser induced fluorescence study, J. Phys. Chem. A., 109, 7732–7741, 2005. Douglas, T. A., Sturm, M., Simpson, W. R., Blum, J. D., Alvarez-Aviles, L., Keeler, G. J., Perovich, D. K., Biswas, A., and Johnson, K.: Influence of snow and ice crystal formation and accumulation on mercury deposition to the Arctic, Environ. Sci. Technol., 42, 1542–1551, 2008. Durnford, D. and Dastoor, A.: The behavior of mercury in the cryosphere: A review of what we know from observations, J. Geophys. Res., 116, D06305, http://dx.doi.org/10.1029/2010JD014809doi:10.1029/2010JD014809, 2011. Durnford, D., Dastoor, A., Figueras-Nieto, D., and Ryjkov, A.: Long range transport of mercury to the Arctic and across Canada. Atmos. Chem. Phys., 10: 6063–6086, http://dx.doi.org/10.5194/acp-10-6063-2010doi:10.5194/acp-10-6063-2010, 2010. Durnford, D. A., Dastoor, A. P., Steen, A. O. , Berg, T., Ryzhkov, A., Figueras-Nieto, D., Hole, L. R., Pfaffhuber, K. A., Hung, H.,: How relevant is the deposition of mercury onto snowpacks? Part 1: A statistical study on~the~impact of environmental factors. Atmos. Chem. Phys. Discuss., 12, 387–439, http://dx.doi.org/10.5194/acpd-12-387-2012doi:10.5194/acpd-12-387-2012, 2012. Fain, X., Ferrari, C. P., Gauchard, P.-A., Magand, O., Boutron, C.: Fast depletion of gaseous elemental mercury in the Kongsvegen Glacier snowpack in Svalbard, Geophys. Res. Lett., 33, L06826, http://dx.doi.org/10.1029/2005GL025223doi:10.1029/2005GL025223, 2006. Faïn, X., Grangeon, S., Bahlmann, E., Fritsche, J., Obrist, D., Dommergue, A., Ferrari, C. P., Cairns, W., Ebinghaus, R., Barbante, C., Cescon, P., and Boutron, C.: Diurnal production of gaseous mercury in the alpine snowpack before snowmelt, J. Geophys. Res., 112, D21311, http://dx.doi.org/10.1029/2007JD008520doi:10.1029/2007JD008520, 2007. Faïn, X., Ferrari, C. P., Dommergue, A., Albert, M., Battle, M., Arnaud, L., Barnola, J.-M., Cairns, W., Barbante, C., Boutron, C.: Mercury in the snow and firn at Summit Station, Central Greenland, and implications for the study of past atmospheric mercury levels, Atmos. Chem. Phys., 8, 3441–3457, http://dx.doi.org/10.5194/acp-8-3441-2008doi:10.5194/acp-8-3441-2008, 2008. Faïn, X., Ferrari, C. P., Dommergue, A., Albert, M. R., Battle, M., Severinghaus, J., Arnaud, L., Barnola, J.-M., Cairns, W., Barbante, C., and Boutron, C.: Polar firn air reveals large-scale impact of anthropogenic mercury emissions during the 1970s, P. Natl. Acad. Sci. USA, 106, 16114–16119, http://dx.doi.org/10.1073/pnas.0905117106doi:10.1073/pnas.0905117106, 2009. Fatnassi, H., Boulard, T., Poncet, C., and Chave, M.: Optimisation of greenhouse insect screening with computational fluid dynamics, Biosyst. Eng., 93, 301–312, 2006. Ferrari, C. P., Dommergue, A., and Boutron, C. F.: Profiles of mercury in the snow pack at Station Nord, Greenland shortly after polar sunrise, Geophys. Res. Lett., 31, L03401, http://dx.doi.org/10.1029/2003GL018961doi:10.1029/2003GL018961, 2004a. Ferrari, C. P., Dommergue, A., Boutron, C. F., Skov, H., Goodsite, M., and Jensen, B.: Nighttime production of elemental gaseous mercury in interstitial air of snow at Station Nord, Greenland, Atmos. Environ., 38, 2727–2735, 2004b. Ferrari, C. P., Gauchard, P.-A., Aspmo, K., Dommergue, A., Magand, O., Bahlmann, E., Nagorski, S., Temme, C., Ebinghaus, R., Steffen, A., Banic, C., Berg, T., Planchon, F., Barbante, C., Cescon, P., Boutron, C. F.: Snow-to-air exchanges of mercury in an Arctic seasonal snow pack in Ny-Ålesund, Svalbard, Atmos. Environ., 39, 7633–7645, 2005. Ferrari, C. P., Padova, C., Faïn, X., Gauchard, P.-A., Dommergue, A., Aspmo, K., Berg, T., Cairns, W., Barbante, C., Cescon, P., Kaleshke, L., Richter, A., Wittrock, F., and Boutron, C.: Atmospheric mercury depletion event study in Ny-Alesund (Svalbard) in spring 2005. Deposition and transformation of Hg in surface snow during springtime, Sci. Total Environ., 397, 167–177, 2008. Fouquart, Y. and Bonnel, B.: Computations of solar heating of the earth's atmosphere: a new parameterization, Contrib. Atmos. Phys., 53, 35–62, 1980. Galbavy, E. S., Anastasio, C., Lefer, B., and Hall, S.: Light penetration in the snowpack at Summit, Greenland: Part 2 nitrate photolysis, Atmos. Environ., 41, 5091–5100, 2007. Garand, L. and Mailhot, J.: The influence of infrared radiation on numerical weather forecasts, in Proceedings of the 7$^th$ Conference on Atmospheric Radiation, J146-J151, American Meteorological Society, USA, 1990. Garbarino, J. R., Snyder-Conn, E., Leiker, T. J., and Hoffman, G. L.: Contaminants in Arctic snow collected over Northwest Alaskan sea ice, Water, Air, Soil Pollut., 139, 183–214, 2002. Gbor, P. K., Wen, D., Meng, F., Yang, F., and Sloan, J. J.: Sloan Modeling of mercury emission, transport and deposition in North America, Atmos. Environ., 41, 1135–1149, 2007. Goulet, R. R., Holmes, J., Page, B., Poissant, L., Siciliano, S. D., Lean, D. R. S., Wang, F., Amyot, M., and Tessier, A.: Mercury transformations and fluxes in sediments of a riverine wetland, Geochim. Cosmochim. Ac., 71, 3393–3406, 2007. Grannas, A. M., Jones, A. E., Dibb, J., Ammann, M., Anastasio, C., Beine, H. J., Bergin, M., Bottenheim, J., Boxe, C. S., Carver, G., Chen, G., Crawford, J. H., Dominé, F., Frey, M. M., Guzmán, M. I., Heard, D. E., Helmig, D., Hoffmann, M. R., Honrath, R. E., Huey, L. G., Hutterli. M., Jacobi, H. W., Klán, P., Lefer, B., McConnell, J., Plane, J., Sander, R., Savarino, J., Shepson, P. B., Simpson, W. R., Sodeau, J. R., von Glasow, R., Weller, R., Wolff, E. W., Zhu, T.: An overview of snow photochemistry: evidence, mechanisms and impacts, Atmos. Chem. Phys., 7, 4329–4373, http://dx.doi.org/10.5194/acp-7-4329-2007doi:10.5194/acp-7-4329-2007, 2007. Hall: The gas phase oxidation of elemental mercury by ozone, Water Air Soil Poll., 80, 301–315, 1995. Hansen, K. M., Halsall, C. J., and Christensen, J. H.: A dynamic model to study the exchange of gas-phase persistent organic pollutants between air and a seasonal snowpack, Environ. Sci. Technol., 40, 2644–2652, http://dx.doi.org/10.1021/es051685bdoi:10.1021/es051685b, 2006. Hare, A., Stern, G. A., Macdonald, R. W., Kuzyk, Z. Z., and Wang, F.: Contemporary and preindustrial mass budgets of mercury in the Hudson Bay Marine System: The role of sediment recycling, Sci. Total Environ., 406, 190–204, http://dx.doi.org/10.1016/j.scitotenv.2008.07.033doi:10.1016/j.scitotenv.2008.07.033, 2008. Hedgecock, I. M., Pirrone, N., and Sprovieri, F.: Chasing quicksilver northward: mercury chemistry in the Arctic troposphere, Environ. Chem., 5, 131–134, 2008. Heidam, N. Z., Christensen, J., Wåhlin, P., and Skov, H.: Arctic atmospheric contaminants in NE Greenland: levels, variations, origins, transport, transformations and trends 1990–2001, Sci. Total Environ., 331, 5–28, 2004. Henderson, P. J., McMartin, I., Hall, G. E., Percival, J. B., and Walker, D. A.: The chemical and physical characteristics of heavy metals in humus and till in the vicinity of the base metal smelter at Flin Flon, Manitoba, Canada, Environmental Geology, 34, 39–58, 1998. Hirdman, D., Aspmo, K., Burkhart, J. F., Eckhardt, S., Sodemann, H., and Stohl, A.: Transport of mercury in the Arctic atmosphere: evidence for a spring-time net sink and summer-time source, Geophys. Res. Lett., 36, L12814, http://dx.doi.org/10.1029/2009GL038345doi:10.1029/2009GL038345, 2009. Holmes, C. D., Jacob, D. J., Corbitt, E. S., Mao, J., Yang, X., Talbot, R., and Slemr, F.: Global atmospheric model for mercury including oxidation by bromine atoms, Atmos. Chem. Phys., 10, 12037–12057, http://dx.doi.org/10.5194/acp-10-12037-2010doi:10.5194/acp-10-12037-2010, 2010. Jackson, T. A.: Long-range atmospheric transport of mercury to ecosystems, and the importance of anthropogenic emissions – a critical review and evaluation of the published evidence, Environ. Rev., 5, 99–120, 1997. Jitaru, P., Gabrielli, P., Marteel, A., Plane, J. M. C., Planchon, F. A. M., Gauchard, P.-A., Ferrari, C. P., Boutron, C. F., Adams, F. C., Hong, S., Cescon, P., and Barbante, C.: Atmospheric depletion of mercury over Antarctica during glacial periods, Nat. Geosci., 2, 505–508, http://dx.doi.org/10.1038/ngeo549doi:10.1038/ngeo549, 2009. Johnson, K. P., Blum, J. D., Keeler, G. J., and Douglas, T. A.: Investigation of the deposition and emission of mercury in arctic snow during an atmospheric mercury depletion event, J. Geophys. Res., 113, D17304, http://dx.doi.org/10.1029/2008JD009893doi:10.1029/2008JD009893, 2008. Kain, J. S. and Fritsch, J. M.: A one-dimensional entraining/detraining plume model and its application in convective parameterization, J. Atmos. Sci., 47, 2784–2802, 1990. Kellerhals, M., Beauchamp, S., Belzer, W., Blanchard, P., Froude, F., Harvey, B., McDonald, K., Pilote, M., Poissant, L., Puckett, K., Schroeder, W., Steffen, A., and Tordon, R.: Temporal and spatial variability of total gaseous mercury in Canada: results from the Canadian Atmospheric Mercury Measurement Network (CAMNet), Atmos. Environ., 37, 1003–1011, 2003. King, M. D. and Simpson, W. R.: Extinction of UV radiation in Arctic snow at Alert, Canada (82° N), J. Geophys. Res., 106, 12499–12507, 2001. Kirk, J. L., St. Louis, V. L., and Sharp, M. J.: Rapid reduction and emission of mercury deposited into snowpacks during atmospheric mercury depletion events at Churchill, Manitoba, Canada, Environ. Sci. Technol., 40, 7590–7596, 2006. Kirk, J. L., St. Louis, V. L., Hintelmann, H., Lehnherr, I., Else, B., and Poissant, L., Methylated mercury species in marine waters of the Canadian high and sub Arctic. Environ. Sci. Tech., 42, 8367–8373, http://dx.doi.org/10.1021/es801635mdoi:10.1021/es801635m, 2008. Kuhn, M.: The nutrient cycle through snow and ice, a review, Aquat. Sci., 63, 150–167, 2001. Lahoutifard, N., Poissant, L., and Scott, S. L.: Scavenging of gaseous mercury by acidic snow at Kuujjuarapik, Northern Québec, Sci. Total Environ., 355, 118–126, 2006. Lalonde, J. D., Poulain, A. J., and Amyot, M.: The role of mercury redox reactions in snow on snow-to-air mercury transfer, Environ. Sci. Technol., 36, 174–178, 2002. Lalonde, J. D., Amyot, M., Doyon, M.-R., and Auclair, J.-C.: Photo-induced Hg(II) reduction in snow from the remote and temperate Experimental lakes Area (Ontario, Canada), J. Geophys. Res., 108, 4200, http://dx.doi.org/10.1029/2001JD001534doi:10.1029/2001JD001534, 2003. Landers, D. H., Ford, J., Gubala, C., Monetti, M., Lasorsa, B. K., and Martinson, J.: Mercury in vegetation and lake sediments from the U.S. Arctic, Water Air Soil Poll., 80, 591–601, 1995. Larose, C., Dommergue, A., De Angelis, M., Cossa, D., Averty, B., Marusczak, N., Soumis, N., Schneider, D., and Ferrari, C.: Springtime changes in snow chemistry lead to new insights into mercury methylation in the Arctic, Geochim. Cosmochim. Ac., 74, 6263–6275, http://dx.doi.org/10.1016/j.gca.2010.08.043doi:10.1016/j.gca.2010.08.043, 2010. Lee-Taylor, J., Madronich, S.: Calculation of actinic fluxes with a coupled atmosphere-snow radiative transfer model, J. Geophys. Res., 107, D24, 4796, http://dx.doi.org/10.1029/2002JD002084doi:10.1029/2002JD002084, 2002. Lin, C.-J., Pongprueksa, P., Lindberg, S. E., Pehkonen, S. O., Byun, D., and Jang, C.: Scientific uncertainties in atmospheric mercury models I: Model science evaluation, Atmos. Environ., 40, 2911–2928, 2006. Lindberg, S. E., Brooks, S., Lin, C.-J., Scott, K. J., Landis, M. S., Stevens, R. K., Goodsite, M., and Richter, A.: Dynamic oxidation of gaseous mercury in the Arctic troposphere at Polar Sunrise, Environ. Sci. Technol., 36, 1245–1256, 2002. Loewen, M., Kang, S., Armstrong, D., Zhang, Q., Tomy, G., and Wang, F.: Atmospheric transport of mercury to the Tibetan Plateau, Environ. Sci. Technol., 41, 7632–7638, 2007. Loseto, L. L., Lean, D. R. S., and Siciliano, S. D.: Snowmelt sources of methylmercury to High Arctic ecosystems, Environ. Sci. Technol., 38, 3004–3010, 2004. Loux, N. T.: Monitoring cyclical air/water elemental mercury exchange, J. Environ. Monit., 3, 43–48, http://dx.doi.org/10.1039/b005545jdoi:10.1039/b005545j, 2001. Lu, J. Y., Schroeder, W. H., Barrie, L. A., Steffen, A., Welch, H. E., Martin, K., Lockhart, L., Hunt, R. V., Boila, G., and Richter, A.: Magnification of atmospheric mercury deposition to polar regions in springtime: the link to tropospheric ozone depletion chemistry, Geophys. Res. Lett., 28, 3219–3222, 2001. Mann, J. L., Long, S. E., Shuman, C. A., and Kelly, W. R.: Determination of mercury content in a shallow firn core from Greenland by isotope dilution inductively coupled plasma mass spectrometry, Water Air Soil Poll., 163, 19–32, 2005. Mann, E., Meyer, T., Mitchell, C. P. J., and Wania, F.: Mercury fate in ageing and melting snow: Development and testing of a controlled laboratory system, J. Environ. Monit., 13, 2695–2702, 2011. Marusczak, N., Larose, C., Dommergue, A., Yumvihoze, E., Lean, D., Nedjai, R., and Ferrari, C.: Total mercury and methylmercury in high altitude surface snow from the French Alps, Sci. Tot. Environ., 409, 3949–3954, 2011. Mason, R.: Mercury emissions from natural processes and their importance in the global mercury cycle, in Mercury fate and transport in the global atmosphere, 173–191, Springer USA, 2009. Maupetit, F., Wagenbach, D., Weddeling, P., and Delmas, R. J.: Seasonal fluxes of major ions to a high altitude cold alpine glacier, Atmos. Environ., 29, 1–9, 1995. McMartin, I., Henderson, P. J., and Nielsen, E.: Impact of a base metal smelter on the geochemistry of soils of the Flin Flon region, Manitoba and Saskatchewan, Can. J. Earth Sci., 36, 141–160, 1999. Mitchell, C. P. J., Branfireun, B. A., and Kolka, R. K.: Assessing sulfate and carbon controls on net methylmercury production in peatlands: An in situ mesocosm approach, Appl. Geochem., 23, 503–518, 2008a. Mitchell, C. P. J., Branfireun, B. A., and Kolka, R. K.: Total mercury and methylmercury dynamics in upland-peatland watersheds during snowmelt, Biogeochemistry, 90, 225–241, http://dx.doi.org/10.1007/s10533-008-9246-zdoi:10.1007/s10533-008-9246-z, 2008b. Nelson, S. J., Johnson, K. B., Weathers, K. C., Loftin, C. S., Fernandez, I. J., Kahl, J. S., and Krabbenhoft, D. P.: A comparison of winter mercury accumulation at forested and no-canopy sites measured with different snow sampling techniques, Appl. Geochem., 23, 384–398, 2008. Outridge, P. M., Macdonald, R. W., Wang, F., Stern, G. A., and Dastoor, A. P.: A mass balance inventory of mercury in the Arctic Ocean, Environ. Chem, 5, 89–111, http://dx.doi.org/10.1071/EN08002doi:10.1071/EN08002, 2008. Pacyna, E. G., Pacyna, J. M., Sundseth, K., Munthe, J., Kindbom, K., Wilson, S., Steenhuisen, F., and Maxson, P.: Global emission of mercury to the atmosphere from anthropogenic sources in 2005 and projections to 2020, Atmos. Environ. 44, 2487–2499, http://dx.doi.org/10.1016/j.atmosenv.2009.06.009doi:10.1016/j.atmosenv.2009.06.009, 2010. Pehkonen, S. O. and Lin, C.-J.: Aqueous photochemistry of mercury with organic acids, J. Air Waste Manage., 48, 144–150, 1998. Perovich, D. K.: Light reflection and transmission by a temperate snow cover, J. Glaciol., 53, 201–210, 2007. Peterson, M., Barber, D., and Green, S.: Monte Carlo modeling and measurements of actinic flux levels in Summit, Greenland snowpack, Atmos. Environ., 36, 2545–2551, 2002. Planchon, F. A. M., Gabrielli, P., Gauchard, P. A., Dommergue, A., Barbante, C., Cairns, W. R. L., Cozzi, G., Nagorski, S. A., Ferrari, C. P., Boutron, C. F., Capodaglio, G., Cescon, P., Varga, A., and Wolff, E. W.: Direct determination of mercury at the sub-picogram per gram level in polar snow and ice by ICP-SFMS, J. Anal. Atom. Spectrom., 19, 823–830, 2004. Poissant, L. and Pilote, M.: Time series analysis of atmospheric mercury in Kuujjuarapik/Whapmagoostui (Québec), J. de Phys. IV: JP, 107, 1079–1082, 2003. Poissant, L., Amyot, M., Pilote, M., and Lean, D.: Mercury water-air exchange over the upper St. Lawrence River and Lake Ontario, Environ. Sci. Technol., 34, 3069–3078, http://dx.doi.org/10.1021/es990719adoi:10.1021/es990719a, 2000. Poulain, A. J., Lalonde, J. D., Amyot, M., Shead, J. A., Raofie, F., and Ariya, P. A.: Redox transformations of mercury in an Arctic snowpack at springtime, Atmos. Environ., 38, 6763–6774, 2004. Poulain, A. J., Garcia, E., Amyot, M., Campbell, P. G. C., and Ariya, P. A.: Mercury distribution, partitioning and speciation in coastal vs. inland High Arctic snow, Geochim. Cosmochim. Ac., 71, 3419–3431, 2007a. Poulain, A. J., Roy, V., and Amyot, M.: Influence of temperate mixed and deciduous tree covers on Hg concentrations and photoredox transformations in snow, Geochim. Cosmochim. Ac., 71, 2448–2462, 2007b. Prestbo, E. M. and Gay, D. A.: Wet deposition of mercury in the U.S. and Canada, 1996–2005: Results and analysis of the NADP mercury deposition network (MDN), Atmos. Environ., 43, 4223–4233, 2009. Raofie, F. and Ariya, P. A.: Kinetics and products study of the reaction of BrO radicals with gaseous mercury, J. Phys., 107, 1119–1121, 2003. Ryaboshapko, A., Bullock, R., Christensen, J., Cohen, M., Dastoor, A., Ilyin, I., Petersen, G., Syrakov, D., Artz, R., Davignon, D., Draxler, R., and Munthe, J.: Intercomparison study of atmospheric mercury models: 1. Comparison of models with short-term measurements, Sci. Total Environ., 376, 228–240, 2007a. Ryaboshapko, A., Bullock, R., Christensen, J., Cohen, M., Dastoor, A., Ilyin, I., Petersen G., Syrakov, D., Travnikov, O., Artz, R., Davignon, D., Draxler, R., Munthe, J., and Pacyna, J.: Intercomparison Study of Atmospheric Mercury Models: 2. Modelling results vs. long-term observations and comparison of country deposition budgets, Sci. Total Environ., 377, 319–333, 2007b. Schuster, P. F., Krabbenhoft, D. P., Naftz, D. L., Cecil, L. D., Olson, M. K., Dewild, J. F., Susong, D. D., Green, J. R., and Abbott, M. L.: Atmospheric mercury deposition during the last 270 years: A glacial ice core record of natural and anthropogenic sources, Environ. Sci. Technol., 36, 2303–2310, 2002. Seigneur, C., Abeck, H., Chia, G., Reinhard, M., Bloom, N. S. Prestbo, E., and Saxena, P.: Mercury adsorption to elemental carbon (soot) particles and atmospheric particulate matter, Atmos. Environ, 32, 2649–2657, 1998. Sherman, L. S., Blum, J. D., Johnson, K. P., Keeler, G. J., Barres, J. A., and Douglas, T. A.: Mass-independent fractionation of mercury isotopes in Arctic snow driven by sunlight, Nat. Geosci., 3, 173–177, http://dx.doi.org/10.1038/ngeo758doi:10.1038/ngeo758, 2010. Shetty, S. K., Lin, C.-J., Streets, D. G., and Jang, C.: Model estimate of mercury emission from natural sources in East Asia, Atmos. Environ., 42, 8674–8685, 2008. Simpson, W. R., King, M. D., Beine, H. J., Honrath, R. E., and Zhou, X.: Radiation-transfer modeling of snow-pack photochemical processes during ALERT 2000, Atmos. Environ., 36, 2663–2670, 2002. Simpson, W. R., Carlson, D., Hönninger, G., Douglas, T. A., Sturm, M., Perovich, D., and Platt, U.: First-year sea-ice contact predicts bromine monoxide (BrO) levels at Barrow, Alaska better than potential frost flower contact, Atmos. Chem. Phys., 7, 621–627, http://dx.doi.org/10.5194/acp-7-621-2007doi:10.5194/acp-7-621-2007, 2007a. Simpson, W. R., von Glasow, R., Riedel, K., Anderson, P., Ariya, P., Bottenheim, J., Burrows, J., Carpenter, L. J., Frieß, U., Goodsite, M. E., Heard, D., Hutterli, M., Jacobi, H.-W., Kaleschke, L., Neff, B., Plane, J., Platt, U., Richter, A., Roscoe, H., Sander, R., Shepson, P., Sodeau, J., Steffen, A., Wagner, T., Wolff, E.: Halogens and their role in polar boundary-layer ozone depletion, Atmos. Chem. Phys., 7, 4375–4418, http://dx.doi.org/10.5194/acp-7-4375-2007doi:10.5194/acp-7-4375-2007, 2007b. Skov, H., Christensen, J. H., Goodsite, M. E., Heidam, N. Z., Jensen, B., Wåhlin, P., and Geernaert, G.: Fate of elemental mercury in the Arctic during atmospheric mercury depletion episodes and the load of atmospheric mercury to the Arctic, Environ. Sci. Technol., 38, 2373–2382, 2004. Snyder-Conn, E., Garbarino, J. R., Hoffman, G. L., and Oelkers, A.: Soluble trace elements and total mercury in Arctic Alaskan snow, Arctic, 50, 201–215, 1997. Soerensen, A. L., Sunderland, E. M., Holmes, C. D., Jacob, D. J., Yantosca, R. M., Skov, H., Christensen, J. H., Strode, S. A., and Mason, R. P.: An improved global model for air-sea exchange of mercury: High concentrations over the North Atlantic, Environ, Sci. Technol., 44, 8574–8580, 2010. Sommar, J., Wängberg, I., Berg, T., Gårdfeldt, K., Munthe, J., Richter, A., Urba, A., Wittrock, F., Schroeder, W. H.: Circumpolar transport and air-surface exchange of atmospheric mercury at Ny-Ålesund (79° N), Svalbard, spring 2002, Atmos. Chem. Phys., 7, 151–166, http://dx.doi.org/10.5194/acp-7-151-2007doi:10.5194/acp-7-151-2007, 2007. Steen, A. O., Berg, T., Dastoor, A. P., Durnford, D. A., Hole, L. R., and Phaffhuber, K. A.: Dynamic exchange of gaseous elemental mercury during polar night and day, Atmos. Environ., 43, 5604–5610, 2009. Steffen, A., Schroeder, W., Bottenheim, J., Narayan, J., and Fuentes, J. D.: Atmospheric mercury concentrations: measurements and profiles near snow and ice surfaces in the Canadian Arctic during Alert 2000, Atmos. Environ., 36, 2653–2661, 2002. Steffen, A., Schroeder, W., Macdonald, R., Poissant, L., and Konoplev, A.: Mercury in the Arctic atmosphere: An analysis of eight years of measurements of GEM at Alert (Canada) and a comparison with observations at Amderma (Russia) and Kuujjuarapik (Canada), Sci. Total Environ., 342, 185–198, 2005. Steffen, A., Douglas, T., Amyot, M., Ariya, P., Aspmo, K., Berg, T., Bottenheim, J., Brooks, S., Cobbett, F., Dastoor, A., Dommergue, A., Ebinghaus, R., Ferrari, C., Gardfeldt, K., Goodsite, M. E., Lean, D., Poulain, A. J., Scherz, C., Skov, H., Sommar, J., Temme, C.: A synthesis of atmospheric mercury depletion event chemistry in the atmosphere and snow, Atmos. Chem. Phys., 8, 1445–1482, http://dx.doi.org/10.5194/acp-8-1445-2008doi:10.5194/acp-8-1445-2008, 2008. St. Louis, V. L., Sharp, M. J., Steffen, A., May, A., Barker, J., Kirk, J. L., Kelly, D. J. A., Arnott, S. E., Keatley, B., and Smol, J. P.: Some sources and sinks of monomethyl and inorganic mercury on Ellesmere Island in the Canadian High Arctic, Environ. Sci. Technol., 39, 2686–2701, 2005. St. Louis, V. L., Hintelmann, H., Graydon, J. A., Kirk, J. L., Barker, J., Dimock, B., Sharp, M. J., and Lehnherr, I.: Methylated mercury species in Canadian High Arctic marine surface waters and snowpacks, Environ. Sci. Technol., 41, 6433–6441, 2007. Stocker, J., Scheringer, M., Wegmann, F., and Hungerbühler, K.: Modeling the Effect of Snow and Ice on the Global Environmental Fate and Long-Range Transport Potential of Semivolatile Organic Compounds, Env. Sci. Technol., 41, 6192–6198, 2007. Strode, S. A., Jaeglé, L., Selin, N. E., Jacob, D. J., Park, R. J., Yantosca, R. M., Mason, R. P., and Slemr, F.: Air-sea exchange in the global mercury cycle, Global Biogeochem. Cy., 21, GB1017, http://dx.doi.org/10.1029/2006GB002766doi:10.1029/2006GB002766, 2007. Sunderland, E. M., Krabbenhoft, D. P., Moreau, J. W., Strode, S. A., and Landing, W. M.: Mercury sources, distribution, and bioavailability in the North Pacific Ocean: Insights from data and models, Global Biogeochem. Cy., 23, GB2010, http://dx.doi.org/10.1029/2008GB003425doi:10.1029/2008GB003425, 2009. Sundqvist, H.: A parameterization scheme for non-convective condensation including prediction of cloud water content, Quart. J. Roy. Meteor. Soc., 104, 677-690, 1978. Temme, C., Blanchard, P., Steffen, A., Banic, C., Beauchamp, S., Poissant, L., Tordon, R., and Wiens, B.: Trend, seasonal and multivariate analysis study of total gaseous mercury data from the Canadian atmospheric mercury measurement network (CAMNet), Atmos. Environ. 41, 5423–5441, 2007. Travnikov, O.: Contribution of the intercontinental atmospheric transport to mercury pollution in the Northern Hemisphere, Atmos. Environ., 39, 7541–7548, 2005. Van Loon, L., Mader, E., and Scott, S. L.: Reduction of the aqueous mercuric ion by sulfite: UV spectrum of HgSO$_\mathrm3$ and its intramolecular redox reaction, J. Phys. Chem. A., 104, 1621–1626, 2000. Van Oostdam, J., Donaldson, S. G., Feeley, M., Arnold, D., Ayotte, P., Bondy, G., Chan, L., Dewaily, É., Furgal, C. M., Kuhnlein, H., Loring, E., Muckle, G., Myles, E., Receveur, O., Tracy, B., Gill, U., Kalhok, S.: Human health implications of environmental contaminants in Arctic Canada: A review, Sci. Total Environ., 351–352, 165–246, 2005. Warren, S. G.: Optical properties of snow, Rev. Geophys. Space Phys., 20, 67–89, 1982. Warren, S. G., Brandt, R. E., and Grenfell, T. C.: Visible and near-ultraviolet absorption spectrum of ice from transmission of solar radiation into snow, Appl. Optics, 45, 5320–5334, 2006. Wen, D., Lin, J. C., Meng, F., Gbor, P. K., He, Z., and Sloan, J. J.: Quantitative assessment of upstream source influences on total gaseous mercury observations in Ontario, Canada, Atmos. Chem. Phys., 11, 1405–1415, http://dx.doi.org/10.5194/acp-11-1405-2011doi:10.5194/acp-11-1405-2011, 2011. Wennberg, P.: Bromine explosion, Nature, 397, 299–301, 1999. Wilke, C. R. and Chang, P.: Correlation of diffusion coefficients in dilute solutions, AIChE J., 1, 264–270, http://dx.doi.org/10.1002/aic.690010222doi:10.1002/aic.690010222, 1955. Witherow, R. A. and Lyons, W. B.: Mercury deposition in a Polar Desert ecosystem, Environ. Sci. Technol., 42, 4710–4716, 2008. Xiao, Z. F., Munthe, J., Stromberg, D., Lindqvist, O.: Photochemical behavior of inorganic mercury compound in aqueous solution, in Mercury as a Global Pollutant –- Integration and Synthesis, edited by: Watras, C. J. and Huckabee, J. W., 581–592, Lewis Publishers, Michigan, USA, 1994. Yang, X., Pyle, J. A., Cox, R. A., Theys, N., and Van Roozendael, M.: Snow-sourced bromine and its implic`ations for polar tropospheric ozone, Atmos. Chem. Phys., 10, 7763–7773, http://dx.doi.org/10.5194/acp-10-7763-1020doi:10.5194/acp-10-7763-1020, 2010. Yue, W., Meneveau, C., Parlange, M. B., Zhu, W., Kang, H. S., and Katz, J.: Turbulent kinetic energy budgets in a model canopy: comparisons between LES and wind-tunnel experiments, Environ. Fluid Mech., 8, 73–95, 2008. Zhang, L., Gong, S., Padro, J., and Barrie, L. A.: A size-segregated particle dry deposition scheme for an atmospheric aerosol module, Atmos. Environ., 35, 549–560, 2001. Zhang, L., Brook, J. R., and Vet, R.: A revised parameterization for gaseous dry deposition in air-quality models, Atmos. Chem. Phys., 3, 2607–2082, http://dx.doi.org/10.5194/acp-3-2067-2003doi:10.5194/acp-3-2067-2003, 2003.