Mercury (Hg) species have been measured in the snow pack at Station Nord, Greenland both in the snow and in the air of snow from February 25 to March 15, 2002, during twilight and low solar irradiation periods. More than 99% of Hg is in the snow itself (∼94–97% as Hg 2+ and ∼5% as MeHg + ) while less than 1% is in the interstitial air of snow as Hg°. Gaseous Elemental Mercury (Hg°) concentrations, decreased exponentially with depth from ∼1.5 ng/m 3 outside to ∼0.1 ng/m 3 at 120 cm depth in the snow air. Hg° incorporation flux to the snow pack has been evaluated to ∼5.8–7.0 pg/m 2 /h which is weak, indicating that this process does not change significantly the Hg content in the snow. We believe that this decrease in the air of snow is the result of fast oxidation processes of Hg° rather than adsorption of Hg° onto snow surfaces.