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Atmospheric Chemistry and Physics An interactive open-access journal of the European Geosciences Union
https://doi.org/10.5194/acp-2018-436
© Author(s) 2018. This work is distributed under
the Creative Commons Attribution 4.0 License.
Research article
06 Jun 2018
Review status
This discussion paper is a preprint. It is a manuscript under review for the journal Atmospheric Chemistry and Physics (ACP).
Understanding mercury oxidation and air-snow exchange on the East Antarctic Plateau: A modeling study
Shaojie Song1,a, Hélène Angot2,3, Noelle E. Selin1,2, Hubert Gallée3, Francesca Sprovieri4, Nicola Pirrone5, Detlev Helmig6, Joël Savarino3, Olivier Magand3, and Aurélien Dommergue3 1Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
2Institute for Data, Systems and Society, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
3Univ. Grenoble Alpes, CNRS, IRD, Grenoble INP, Institut des Géosciences de l’Environnement (IGE), 38000 Grenoble, France
4CNR-Institute of Atmospheric Pollution Research, Division of Rende, Italy
5CNR-Institute of Atmospheric Pollution Research, Montelibretti, Rome, Italy
6Institute of Arctic and Alpine Research (INSTAAR), University of Colorado, Boulder, Colorado 80309-0450, USA
anow at: School of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts 02138, USA
Abstract. Distinct diurnal and seasonal variations of mercury (Hg) have been observed in near-surface air at Concordia station on the East Antarctic Plateau, but the processes controlling these characteristics are not well understood. Here, we use a box model to interpret the Hg0 (gaseous elemental mercury) measurements in year 2013. The model includes atmospheric Hg0 oxidation (by OH, O3, or bromine), surface snow HgII (oxidized mercury) reduction, and air-snow exchange, and is driven by meteorological fields from a regional climate model. The simulations suggest that a photochemically driven mercury diurnal cycle occurs at the air-snow interface in austral summer. The fast oxidation of Hg0 in summer may be provided by a two-step bromine-initiated scheme, which is favored by low temperature and high nitrogen oxides at Concordia. The summertime diurnal variations of Hg0 (peaking during daytime) may be confined within several tens of meters above the snow surface and affected by changing mixed layer depths. Snow reemission of Hg0 is mainly driven by photoreduction of snow HgII in summer. Intermittent warming events and a hypothesized reduction of HgII occurring in snow in the dark may be important processes controlling the mercury variations in the non-summer period, although their relative importance are uncertain. The Br-initiated oxidation of Hg0 is expected to be slower at Summit Greenland than at Concordia (due to their difference in temperature and levels of nitrogen oxides and ozone), which may contribute to the observed differences in the summertime diurnal variations of Hg0 between these two polar inland stations.
Citation: Song, S., Angot, H., Selin, N. E., Gallée, H., Sprovieri, F., Pirrone, N., Helmig, D., Savarino, J., Magand, O., and Dommergue, A.: Understanding mercury oxidation and air-snow exchange on the East Antarctic Plateau: A modeling study, Atmos. Chem. Phys. Discuss., https://doi.org/10.5194/acp-2018-436, in review, 2018.
Shaojie Song et al.
Shaojie Song et al.
Shaojie Song et al.

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