| Summary: | This work presents the distribution of oxygen isotope ratios in the surface snow in the West Antarctic Ice Sheet during the Chilean-Brazilian traverse held in the austral summer of 2004/2005. The traverse was carried out from Chilean Antarctic station Tenente Parodi, in Patriot Hills (80°18’S, 81°21’W) and the Geographic South Pole, along more than 1.205 km. We collected superficial snow samples of the upper 0.05 to 0.2 m deep, approximately at each 10 km (total of 104 samples). The average annual temperature was determined at six points spaced approximately 220 km apart, at a depth between 10 and 15 m. The oxygen isotope ratio (δ 18O) of each sample was determined by mass spectrometry with gas source (GSMS - Gas Source Mass Spectrometry) with a 0.05 ‰ precision. Results point out to the strong correlation between δ18O and the local temperature, latitude, altitude and distance from the coast, the first being positive and the others negative. Anomalous relatively high isotopic values are found between 87°30’S and 86°44’S, which are associated to post-depositional processes due to formation of glaze ice as identified in the field. The gradient δ 18O/Altitude is -0.08‰/100 m and the δ 18O/Temperature is 0.743‰/°C. Excepting for the cited anomalies, results are consistent with those found by other researchers in the Antarctic ice sheet. Este trabalho apresenta a variabilidade das razões de isótopos de oxigênio na neve superficial ao longo de uma travessia do manto de gelo da Antártida ocidental realizada no verão austral de 2004/2005 por uma expedição conjunta entre pesquisadores chilenos e brasileiros. A travessia foi realizada entre a estação chilena Tenente Parodi, em Patriot Hills (80°18’S, 081°21’W) e o Polo Sul geográfico, cobrindo uma distância de mais de 1.205 km. Foram coletadas amostras de neve superficial (entre 0,05 a 0,2 m de profundidade) aproximadamente a cada 10 km (total de 104 amostras). A temperatura média anual foi obtida em seis pontos espaçados aproximadamente 220 km entre si, a uma ...
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