Net deposition of mercury to the Antarctic Plateau enhanced by sea salt

Photochemically driven mercury (Hg) exchange between the atmosphere and the Antarctic Plateau snowpack has been observed. An imbalance in bidirectional flux causes a fraction of Hg to remain in the snowpack perennially, but the factors that control the amount of Hg sequestered on the Antarctic Plateau are not fully understood. We analyzed sub-annual variations in total Hg (Hg_T) deposition to Dome Fuji over the period of 1986-2010 using cold vapor inductively coupled plasma mass spectrometry and compared concentrations with those of sea salt components (Na⁺ and Cl^-). Hg_T ranged from 0.12 to 5.19pgg^-1 (n=78) and was relatively high when the Na⁺ concentrations were high in the same or underlying snow layers. A significant correlation (r=0.7) was found between the annual deposition fluxes of Hg_T and Na⁺. Despite different origins and behavior of Hg and sea salt, the near-synchronous increases in the concentrations and correlation between the fluxes suggest that sea salt can intervene in the air-snow Hg exchange and promote the net deposition of Hg in the Antarctic Plateau.