Journal cover Journal topic
Atmospheric Chemistry and Physics An interactive open-access journal of the European Geosciences Union
Atmos. Chem. Phys., 16, 8249-8264, 2016
https://doi.org/10.5194/acp-16-8249-2016
© Author(s) 2016. This work is distributed under
the Creative Commons Attribution 3.0 License.
Research article
08 Jul 2016
New insights into the atmospheric mercury cycling in central Antarctica and implications on a continental scale
Hélène Angot1, Olivier Magand2,1, Detlev Helmig3, Philippe Ricaud4, Boris Quennehen2,1, Hubert Gallée2,1, Massimo Del Guasta5, Francesca Sprovieri6, Nicola Pirrone7, Joël Savarino2,1, and Aurélien Dommergue1,2 1Univ. Grenoble Alpes, Laboratoire de Glaciologie et Géophysique de l'Environnement (LGGE), 38041 Grenoble, France
2CNRS, Laboratoire de Glaciologie et Géophysique de l'Environnement (LGGE), 38041 Grenoble, France
3Institute of Arctic and Alpine Research (INSTAAR), University of Colorado, Boulder, CO 80309-0450, USA
4CNRM/GAME, Météo-France/CNRS, 42 avenue de Coriolis, 31057 Toulouse, France
5CNR-Istituto Nazionale di Ottica, Largo E. Fermi 6, Firenze, 50125, Italy
6CNR-Institute of Atmospheric Pollution Research, Division of Rende, Italy
7CNR-Institute of Atmospheric Pollution Research, Montelibretti, Rome, Italy
Abstract. Under the framework of the GMOS project (Global Mercury Observation System) atmospheric mercury monitoring has been implemented at Concordia Station on the high-altitude Antarctic plateau (75°06′ S, 123°20′ E, 3220 m above sea level). We report here the first year-round measurements of gaseous elemental mercury (Hg(0)) in the atmosphere and in snowpack interstitial air on the East Antarctic ice sheet. This unique data set shows evidence of an intense oxidation of atmospheric Hg(0) in summer (24-hour daylight) due to the high oxidative capacity of the Antarctic plateau atmosphere in this period of the year. Summertime Hg(0) concentrations exhibited a pronounced daily cycle in ambient air with maximal concentrations around midday. Photochemical reactions and chemical exchange at the air–snow interface were prominent, highlighting the role of the snowpack on the atmospheric mercury cycle. Our observations reveal a 20 to 30 % decrease of atmospheric Hg(0) concentrations from May to mid-August (winter, 24 h darkness). This phenomenon has not been reported elsewhere and possibly results from the dry deposition of Hg(0) onto the snowpack. We also reveal the occurrence of multi-day to weeklong atmospheric Hg(0) depletion events in summer, not associated with depletions of ozone, and likely due to a stagnation of air masses above the plateau triggering an accumulation of oxidants within the shallow boundary layer. Our observations suggest that the inland atmospheric reservoir is depleted in Hg(0) in summer. Due to katabatic winds flowing out from the Antarctic plateau down the steep vertical drops along the coast and according to observations at coastal Antarctic stations, the striking reactivity observed on the plateau most likely influences the cycle of atmospheric mercury on a continental scale.

Citation: Angot, H., Magand, O., Helmig, D., Ricaud, P., Quennehen, B., Gallée, H., Del Guasta, M., Sprovieri, F., Pirrone, N., Savarino, J., and Dommergue, A.: New insights into the atmospheric mercury cycling in central Antarctica and implications on a continental scale, Atmos. Chem. Phys., 16, 8249-8264, https://doi.org/10.5194/acp-16-8249-2016, 2016.
Publications Copernicus
Short summary
While the Arctic has been extensively monitored, there is still much to be learned from the Antarctic continent regarding the processes that govern the budget of atmospheric mercury species. We report here the first year-round measurements of gaseous elemental mercury (Hg(0)) in the atmosphere and in snowpack interstitial air on the East Antarctic ice sheet. The striking reactivity observed on the Antarctic plateau most likely influences the cycle of atmospheric mercury on a continental scale.
While the Arctic has been extensively monitored, there is still much to be learned from the...
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