Mercury in the snow and firn at Summit Station, Central Greenland, and implications for the study of past atmospheric mercury levels X. Faïn1, C. P. Ferrari1,4,7, A. Dommergue1,4, M. Albert2, M. Battle3, L. Arnaud1, J.-M. Barnola1, W. Cairns5, C. Barbante5, and C. Boutron1,6,7 1Laboratoire de Glaciologie et Géophysique de l'Environnement (UMR 5183 CNRS/Université Joseph Fourier), 54 rue Molière, B.P. 96, 38402 St Martin d'Heres cedex, France 2Geophysical Sciences Division – ERDC Cold Regions Research & Engineering Lab, 72 Lyme Road, Hanover, N.H. 03755, USA 3Dept. of Physics and Astronomy – Bowdoin College, 8800 College Station, Brunswick, ME 04011-8488, USA 4Polytech' Grenoble, Université Joseph Fourier, 28 avenue Benoît Frachon, B.P. 53, 38041 Grenoble cedex, France 5Environmental Sciences Department, University of Venice, Calle Larga S. Marta, 2137, 30123 Venice, Italy 6Unité de Formation et de Recherche de Physique, Université Joseph Fourier, B.P. 53, 38041 Grenoble cedex, France 7Institut Universitaire de France, 103 boulevard Saint-Michel, 75005 Paris, France
Abstract. Gaseous Elemental Mercury (Hg° or GEM) was investigated at Summit
Station, Greenland, in the interstitial air extracted from the perennial
snowpack (firn) at depths ranging from the surface to 30 m, during
summer 2005 and spring 2006. Photolytic production and destruction of Hg°
were observed close to the snow surface during summer 2005 and spring
2006, and we observed dark oxidation of GEM up to 270 cm depth in June 2006.
Photochemical transformation of gaseous elemental mercury resulted in diel variations
in the concentrations of this gas in the near-surface interstitial air, but
destruction of Hg° was predominant in June, and production was the main
process in July. This seasonal evolution of the chemical mechanisms
involving gaseous elemental mercury produces a signal that propagates
downward through the firn air, but is unobservably small below 15 m in
depth. As a consequence, multi-annual averaged records of GEM concentration
should be well preserved in deep firn air at depths below 15 m, and
available for the reconstruction of the past atmospheric history of GEM over
the last decades.
Citation: Faïn, X., Ferrari, C. P., Dommergue, A., Albert, M., Battle, M., Arnaud, L., Barnola, J.-M., Cairns, W., Barbante, C., and 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, doi:10.5194/acp-8-3441-2008, 2008.