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

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.