Preliminary results from measurements of selected trace metals in the snow-firn pack on Ürümqi glacier No. 1, eastern Tien Shan, China

Abstract

We present preliminary results on the occurrence of Pb, Cd, Zn, Al and Fe in dated samples collected from snow-firn packs at an altitude of 4130 m on Ürümqi glacier No. 1, eastern Tien Shan. Extreme precautions for avoiding contamination were taken throughout the sampling, processing, transportation and analysis procedures. The concentrations of trace metals were determined by a double-focusing inductively coupled plasma mass spectrometer in an ultra-clean room. The average concentrations for these metals in surface snow are (in ng g-1): Pb, 2.4; Cd, 0.05; Zn, 10.0; Al, 100.0; and Fe, 130.0. These are higher concentrations (especially for Pb and Zn) than those in the polar and/or low-latitude remote areas. The data show that the input of trace metals to the snow has a clear seasonal change. Lower concentrations in surface snow can be found in July through September and higher concentrations from October to March, with an exception for January. The mean concentrations of the elements in the snow-firn pack also indicate seasonal variations and show a marked inverse relationship with temperature, possibly a result of meltwater percolation in the snow-firn pack.