Atmospheric trace elements in Antarctic prehistoric ice collected at a coastal ablation area

International audienceWe present here the results of the analysis of 22 elements or compounds in a large block of prehistoric blue ice more than 12000 years old collected at a coastal ablation area in east Antarctica. Successive veneer layers chiselled in sequence from the exterior to the center have been analysed separately in order to determine the contamination characteristics of the block.Concentrations measured in the central parts probably represent the original concentrations in the prehistoric blue ice, thus giving estimates of pre-man natural reference, levels of these elements or compounds in Antarctic precipitations. For the enriched elements Cd, Cu, Zn, Au, Se and for SO4, concentrations are shown not to differ significantly from those presently observed in surface snow in the central plateau areas from which the ice is thought to originate. This suggests that the remote polar regions of the southern hemisphere are still little affected by global pollution for these elements and for S compounds. For crustal derived elements, concentrations in prehistoric ice are found to be significantly higher than those in present day snow; this confirms that crustal flux to the Antarctic continent was higher during Wisconsin times than now