Composizione chimica della neve e del ghiaccio nella Valle del Khumbu (Sagarmatha National Park, Himalaya, Nepal)

Snow and ice chemical composition in the Khumbu Valley (Sagarmatha National Park, Himalaya, Nepal)

Abstract

In 1998, fresh surface snow samples were collected, no more than two days after the snowfall, along the Khumbu valley and its lateral valleys (Kongma La and Changri Nup), at the end of the summer monsoon period. Samples from the Island Peak and Pumori slopes were also collected by climbers during pre- and post-monsoon season at altitudes ranging from 5300 to 6100 m a.s.l. Two series of ice samples from seracs of two different glaciers (Changri Nup and Khumbu Glaciers) were also collected and analyzed. Conductivity, pH, and major inorganic ions were measured in samples and relative field blanks. Chemical results were interpreted in order to distinguish different sources of ions and study spatial and temporal distribution of ion concentrations. Two different sources have been identified: one correlated with calcium and sulfate, which represents local transport and background contribution, and the other, correlated with sodium and chloride, which is related to monsoon circulation. The orographic and micrometeorological influence on the chemical composition of the snow in the different sites has been discussed.