Sources and spatial variation of the chemical composition of snow in the Tien Shan, China

Abstract

Research on the sources and spatial variation of the chemical content of snow was conducted in four headwater basins of the eastern Tien Shan, China. The mean SO42-concentration of 16.2 μeq L-1was three-fold greater than background concentrations from other remote areas of the world. About 80% of the SO42-in snow was deposited in association with Ca2+and Mg2+, partially accounting for the relatively high pH of 6.34 in new snow. The variance of individualions in the snowpack ranged from 24 to 46%, measured as the standard deviation divided by the mean and based on 59 samples. Analysis of variance tests showed that solute concentrations varied significantly among sites within an individual basin and that the mean solute concentrations did not vary significantly among basins. Aeolian dust in the snowpack resulted in significant post-depositional alterations in the solute content of snow. Mineral weathering of the dust in the snowpack of the Tien Shan mproduced alkalinity and Ca2+, increasing conductance and buffering H+.