GLACIOCHEMISTRY OF A SHALLOW ICE CORE FROM THE WEST ANTARCTIC ICE SHEET: SOURCES AND IMPLICATIONS

The Amundsen Sea sector of the West Antarctic Ice Sheet (WAIS) is undergoing significant warming and contains fast-moving glaciers contributing to global sea-level rise. Here we present preliminary major ion data (Ca²⁺, Mg²⁺, K⁺, Na⁺, NH₄⁺, Cl^-, NO₃^-, SO₄^2-) as well as calculated sea-salt Na⁺ and non-sea-salt Ca²⁺ and SO₄^2-from a shallow (10m) core from the WAIS. The core was collected in January 2011 and covers approximately the previous decade (October 2001 – January 2011). The chemistry of solid precipitation found in polar ice cores is the primary record for reconstructing atmospheric chemistry and climate through the recent geologic past. With increased ability to measure soluble major and organic ionic species at low concentrations comes a better-resolved environmental record. The goals of this study are two-fold. The first is to establish the use of dual ion chromatographs to simultaneously measure dissolved anions and cations in Antarctic ice and snow samples while minimizing both detection limits and sample size. The second is to use these data to examine potential climate and moisture source information and assess the links between sea-ice coverage and ion concentration. Ions were measured on 3-5 cm core sections using a paired Ion Chromatograph system allowing for 0.5 to 10 ppb detection limits using only 3 mL of sample. The cations in this shallow core are dominated by calcium and sodium while the anionic load is relatively evenly distributed between chloride and sulfate, with smaller nitrate input. This region has been shown to be strongly influenced by sea-ice dynamics in local polynyas. As such, initial results from our analysis show strong seasonality in overall ion concentration, sea-salt input, and sea ice variability in polynyas within the region.