Relation between surface topography and sea-salt snow chemistry from Princess Elizabeth Land, East Antarctica

Abstract

Previous studies on Antarctic snow have established an unambiguous correlation between variability of sea-salt records and site specific features like elevation and proximity to the sea. On the other hand, variations of Cl^-/Na⁺ ratios in snow have been attributed to the reaction mechanisms involving atmospheric acids. In the present study, the annual records of Na⁺, Cl^- and SO₄^2-− were investigated using snow cores along a 180 km coast to inland transect in Princess Elizabeth Land, East Antarctica. Exceptionally high Na+ concentrations and large variations in Cl^-/Na⁺ ratios were observed up to 50 km (∼1100 m elevation) of the transect. The steepest slope in the entire transect (49.3 m km−1) was between 20 and 30 km and the sea-salt records in snow from this area revealed extensive modifications, with Cl^-/Na⁺ ratios as low as 0.2. Statistical analysis showed a strong association between the slope and variations in Cl^-/Na+ ratios along the transect (r = −0.676, 99% confidence level). While distance from the coast accounted for some variability, the altitude by itself has no significant control over the sea-salt ion variability. However, the steep slopes influence the deposition of sea-salt aerosols in snow. The wind redistribution of snow due to the steep slopes on the coastal escarpment increases the concentration of Na⁺, resulting in a low Cl^-/Na⁺ ratios. We propose that the slope variations in the coastal regions of Antarctica could significantly influence the sea-salt chemistry of snow.