Atmos. Chem. Phys. Discuss., 4, 1727-1771, 2004
www.atmos-chem-phys-discuss.net/4/1727/2004/
doi:10.5194/acpd-4-1727-2004
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This discussion paper has been under review for the journal Atmospheric Chemistry and Physics (ACP). Please refer to the corresponding final paper in ACP.
Circumpolar transport and air-surface exchange of atmospheric mercury at Ny-Ålesund (79° N), Svalbard, spring 2002
J. Sommar1, I. Wängberg2, T. Berg3, K. Gårdfeldt1, J. Munthe2, A. Richter4, A. Urba5, F. Wittrock4, and W. H. Schroeder6
1Department of Chemistry, Göteborg University, Kemivägen 4, 41296 Göteborg, Sweden
2IVL Swedish Environmental Research Institute, P.O. Box 47086, 40258 Göteborg, Sweden
3Norwegian Institute for Air Research (NILU), P.O. Box 100, 2027 Kjeller, Norway
4Institute of Environmental Physics, University of Bremen, NW1, Otto-Hahn-Allee 1, 28359 Bremen, Germany
5Ecological Spectroscopy Laboratory, Institute of Physics, Gostauto 12, 2600 Vilnius, Lithuania
6Environmental Canada: Meteorological Service of Canada, 4905 Dufferin Street, Toronto, Canada

Abstract. Mercury in different environmental compartments has been measured at Ny-Ålesund (78°54′ N, 11°53′ E) during an intensive campaign, 17 April to 14 May 2002. Time-resolved speciated determination of mercury in the atmosphere and snow was conducted at the Norwegian research station at the Zeppelin mountain, 474 m above the sea level, and at the Italian research facility Dirigibile Italia, 12 m above the sea level. Total Gaseous Mercury (TGM) was present in the range <0.1 to 2.2 ng m−3 during the campaign. Three mercury depletion events, identified as periods with decreased TGM concentrations, were observed. At the lower altitude, TGM concentrations following such events were found to exhibit both higher magnitude and larger variability in comparison to results from the Zeppelin station. Oxidised mercury species in air and fall-out with snow as well as mercury attached to particles were also measured and their concentrations were found to be anti-correlated with TGM in air. The strongest modulation was observed for total mercury concentration (Hg-tot) in snow (range 1.5–76.5 ng L−1). Solid evidence for photo-stimulated emissions of Hg0(g) from the snow pack in conjunction to depletion events were obtained from gradient measurements as well as from flux chamber measurements. Steep diurnal concentration variations of Hg0(aq) in surface seawater were also found to concur with changing solar radiation. The concentration of Hg0(aq) in seawater was found to be in the range 12.2–70.4 pg L−1, which corresponds to supersaturation. Hence, the seawater surface constituted a source emitting elemental mercury. The concentrations of the transient mercury forms RGM (Reactive Gaseous Mercury) and PM (Particulate Mercury) respectively and BrO column densities detected using a zenith and off-axis sky viewing DOAS instrument were very low except for a few individual samples during the major depletion event. An evaluation of trajectories for selected events and comparisons with BrO vertical column densities obtained by the GOME (Global Ozone Monitoring Experiment) instrument aboard the earth remote sensing satellite ESR-2 indicates that the air masses exhibiting low Hg0 concentrations originated from areas with high BrO densities. It was concluded that the observed depletion events at Ny-Ålesund were a results of transport from areas with high photochemical activity around the polar region.

Citation: Sommar, J., Wängberg, I., Berg, T., Gårdfeldt, K., Munthe, J., Richter, A., Urba, A., Wittrock, F., and Schroeder, W. H.: Circumpolar transport and air-surface exchange of atmospheric mercury at Ny-Ålesund (79° N), Svalbard, spring 2002, Atmos. Chem. Phys. Discuss., 4, 1727-1771, doi:10.5194/acpd-4-1727-2004, 2004.
 
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