Dynamic recycling of gaseous elemental mercury in the boundary layer of the Antarctic Plateau

• Published in: Atmospheric Chemistry and Physics
• Main Authors: A. Dommergue, M. Barret, J. Courteaud, P. Cristofanelli, C. P. Ferrari, H. Gallée
• Format: Article in Journal/Newspaper
• Language: English
• Published: Copernicus Publications 2012
• Subjects: Physics; QC1-999; Chemistry; QD1-999; Arctic; Antarctic; The Antarctic; Concordia Station; Antarc*
• Online Access: https://doi.org/10.5194/acp-12-11027-2012; https://doaj.org/article/8c2ddf5feaec4973aabd2949fe550da7

Gaseous elemental mercury (Hg 0 ) was investigated in the troposphere and in the interstitial air extracted from the snow at Dome Concordia station (alt. 3320 m) on the Antarctic Plateau during January 2009. Measurements and modeling studies showed evidence of a very dynamic and daily cycling of Hg 0 inside the mixing layer with a range of values from 0.2 ng m −3 up to 2.3 ng m −3 . During low solar irradiation periods, fast Hg 0 oxidation processes in a confined layer were suspected. Unexpectedly high Hg 0 concentrations for such a remote place were measured under higher solar irradiation due to snow photochemistry. We suggest that a daily cycling of reemission/oxidation occurs during summer within the mixing layer at Dome Concordia. Hg 0 concentrations showed a negative correlation with ozone mixing ratios, which contrasts with atmospheric mercury depletion events observed during the Arctic spring. Unlike previous Antarctic studies, we think that atmospheric Hg 0 removal may not be the result of advection processes. The daily and dramatic Hg 0 losses could be a consequence of surface or snow induced oxidation pathways. It remains however unclear whether halogens are involved. The cycling of other oxidants should be investigated together with Hg species in order to clarify the complex reactivity on the Antarctic plateau.