Spatial and temporal variability of sea-salts in ice cores and snow pits from Fimbul Ice Shelf, Antarctica
The Cryosphere Discussions
Major ions were analysed in three firn cores from different ice rises located at Fimbul Ice Shelf (FIS): Kupol Ciolkovskogo (KC), Kupol Moskovskij (KM), and Blåskimen Island (BI), a 100&thinsp;m long core drilled near the FIS edge (S100), and five snow pits (M1, M2, G3, G4, and G5) sampled on the ice shelf. These sites are distributed over the entire FIS area so that they provide a variety of elevation and distance to the sea. Sea-salt species (mainly Na<sup>+</sup> and
... l<sup>&minus;</sup>) generally dominate the precipitation chemistry in the study region. Concentrations of these ions were found to decrease with latitude and distance from the sea. We associate a significant six-fold increase in sea-salts observed in the S100 core after the 1950s with a change in deposition regime. This increase in sea-salt concentrations is synchronous with a shift in non-sea-salt sulfate (nssSO<sub>4</sub><sup>2&minus;</sup>) toward negative values, suggesting a possible contribution of fractionated aerosol to the sea-salt load in the S100 core most likely by dry deposition. In contrast, wet deposition of atmospheric sea-salts is dominant in the three ice rises cores, and no evidence of a significant contribution of fractionated sea-salt to these sites was found. In summary, these results suggest that the S100 core contains a more local sea-salt signal, dominated by processes during sea-ice formation in the neighbouring waters. In contrast, the ice rises cores register the larger-scale signal of atmospheric flow conditions and transport of sea-salt aerosols produced over open water rather than local changes in sea-ice, wind-blown snow accumulated over sea-ice, and frost flower formation. These findings are a contribution to the understanding of the mechanisms behind sea-salt aerosol production, transport and deposition at coastal Antarctic sites, and for the improvement of the current Antarctic sea-ice reconstructions based on sea-salt chemical proxies obtained from ice cores.