Chemical and radio-chemical composition of freshsnow samples from northern slopes of Himalayas (Cho Oyu range, Tibet)

In September and October 2000, during a scientific and mountaineering expedition (Rome 8000), a continuous series of daily snowfalls have been sampled during the final monsoon and post-monsoon season. The sampling sites were the Gyabrag glacier and the Mt. Cho Oyu west buttress, in the northern slope of the Himalayas range. Samples of freshsnow were collected at different altitudes, ranging from 5700 to 6400m a.s.l. in the same day and for the same precipitation. Contemporarily, some snow trenches were dug and snow layers were studied and sampled. Conductivity, pH and the major inorganic ions have been analysed with their relative field blanks. The results obtained in the Cho Oyu area have been compared to the ones reported in literature for the southern slopes of the Himalayas range. The comparison shows a substantial homogeneity of main ions concentrations in freshsnow, not depending on the geographical location but only on the monsoon alternation. Fresh snow data showed differences between the monsoon season, with values not substantially influenced by anthropogenic inputs, and the extra-monsoon (post-monsoon, winter and pre-monsoon) season characterised by the influence of dust from central Asia. Some experimental results of in situ radioactivity measurements, obtained with a portable g-ray detector, are also presented