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Chemical and isotopic snow variability along the 1998 ITASE traverse from Terra Nova Bay to Dome C, East Antarctica

2002; Cambridge University Press; Volume: 35; Linguagem: Inglês

10.3189/172756402781817167

1727-5644

Marco Proposito, Silvia Becagli, E. Castellano, O. Flora, L. Genoni, R. Gragnani, Barbara Stenni, Rita Traversi, R. Udisti, Massimo Frezzotti,

Arctic and Antarctic ice dynamics

Abstract In the framework of the PNRA–ITASE (Programma Nazionale di Ricerche in Antartide–International Trans-Antarctic Scientific Expedition) project, during the field season 1998/99, surface snow (1m cores and pits) and shallow firn cores (10–50m) were collected along a traverse from Terra Nova Bay (northern Victoria Land) to Dome C (East Antarctic ice sheet). Results of chemical, tritium and stable-isotope composition are presented here for the 1 m cores, some snow pits and the first 2 mof some shallow firn cores. the δ 18 O values show a regular trend with altitude, and the regression line between δ 18 O and surface temperature is δ 18 O = 0.99T (˚C) – 0.67. Primary aerosol components such as Na + , Cl – , Ca 2+ ,Mg 2+ and K + show high concentrations decreasing with increasing altitude in the first 250–350km from the coast. At greater distances, concentrations of these species remain more constant. NO 3 – concentration shows an irregular profile with a progressive decreasing trend as altitude increases. Non-sea-salt (nss) SO 4 2– concentration decreases up to about 250 km from the coast, increases 250–770 km from the coast and remains relatively constant in the most remote stations. Methanesulphonate (MSA) concentration shows high variability. the MSA/nssSO 4 2– ratio exhibits a decreasing trend 250–550km from the coast. With increasing distance, the ratio shows moderate oscillations. nssCl – concentration shows a progressive increase as distance from the coast increases, in agreement with the increasing influence of HCl on the Cl – budget of the inland Antarctic atmosphere. Post-depositional re-emissions of Cl – and NO 3 – were found at stations characterized at the surface by long-term accumulation hiatus (wind crusts). the chemical-species distribution is consistent with the presence in the studied area of local and long-range transport processes, post-depositional effects and snow-accumulation variations observed along the traverse.