Springtime atmospheric mercury speciation in the McMurdo, Antarctica coastal region

This paper describes springtime atmospheric mercury (Hg) speciation and snow pack mercury concentration measurements in the McMurdo/Ross Island sea ice region of Antarctica. Near-surface gaseous elemental mercury (GEM) depletions (to concentrations below our detection limit, <0.01 ng m−3), similar to those shown to occur in the springtime Arctic, were observed and reactive gaseous mercury (RGM) and fine particulate mercury (FPM) were produced in significant quantities (average 116 and 49 pg(Hg) m−3, respectively). GEM concentrations in the near-surface air were significantly enhanced during brief afternoon terrestrial snowmelt events. Snow pack total mercury was significantly elevated (40–430 ng l−1), with a maximum at the northern extent of the fast-ice (adjacent to the grease ice/freezing ocean surface), and lesser values towards the coast and on Ross Island, suggesting that, similarly again to recent Arctic results, marine halogens, released by the freezing sea surface, induce localized mercury depletion events. A possible secondary contributing source of local halogens and mercury are direct emissions from the active Ross Island volcano, Mt. Erebus.