Characteristics of Surface Dust on Ürümqi Glacier No. 1 in the Tien Shan Mountains, China

Abstract

Monitoring studies show that many mountain glaciers worldwide are decreasing in mass. An important component of the process of ice mass loss is the effect of dust on albedo and its effect on glacier mass balance. The characteristics of surface dust were investigated in August 2006 on the Ürümqi Glacier No. 1 in the Tien Shan Mountains, China. The bare ice surface of the glacier was mostly covered by brown dust. The amounts of surface dust on the ice surface (dry weight) ranged from 86 to 1113 g m−2 (mean: 335 g m−2, standard deviation: = 211), which is within the normal range for Asian glaciers, but significantly greater than those on glaciers in other regions such as Alaska, Patagonia, and the Canadian Arctic. An analysis of organic matter and microscopy of the surface dust revealed that the dust contained high levels of organic matter, including living cyanobacteria. This suggests that it is comprised not only of deposits of wind-blown desert dust, but is also a product of microbial activity on the glacier itself. Spectral albedo of the glacial surface showed spectrum curves typical of those of snow and ice contaminated with dust. The integrated surface albedo ranged from 0.09 to 0.24 (mean: 0.14) in the ice area, from 0.50 to 0.64 (mean: 0.56) in the snow area. The lower albedo on the glacial surface compared with that of clean bare ice or snow surface suggests that the albedo was significantly reduced by the surface dust on this glacier. Results suggest that the mineral and organic dust on the glacial surface substantially accounts for the recent shrinkage of the glacier.