Mineral and Elemental Characteristics of Microparticles with Different Size Fraction in Snowpits from Zadang Glacier
扎当冰川雪坑中不同粒径微粒元素和矿物组成特征

In order to study the mineral and elemental composition of insoluble microparticles (IP) in snow/ice, two snowpits were collected from the Zadang Glacier in Mt. Nyainqentanglha (30.47 degrees N, 90. 65 degrees E, 5 800 m a. s. l) in May and July, 2009, and IP samples were investigated. The measurements of mineral composition with different size fractions (d > 10 microm and 0.22 microm < d < 10 microm) were carried out using Particle-induced X-ray emission (PIXE) and X-ray diffraction analysis (XRD). The main mineral components of both coarse and fine IP are quartz, mica and calcite, accounting for 71.5% and 76.5%, respectively. The crustal elements concentrations (e.g. Si, Al, Fe, K, Mg and Ca) are 97% and 85.1% of total coarse/fine IP, while S, Cl and P take fairly proportion in fine microparticles (d < 10 microm). Seasonal variability of mineral composition in coarse microparticles (d >10 microm) is not obviously; However it's significantly in fine IP. Enrichment factors (EF) analysis reveals that several elements (e.g. Sc, P, Cr, S and Cl) in fine IP during monsoon season have high values which indicate these elements may be influenced by anthropogenic activities. Backward air mass trajectory analysis suggests that air masses in this region mainly originate from the South Asia areas during monsoon season, and air masses mainly come from arid/semi-arid region in the South and West Asia during non-monsoon season. Therefore, anthropogenic pollutants from the South Asia may be transported by the summer Indian monsoon to the Zadang glacier area. The coarse IP may derive from the local or remote mineral dust, and chemical compositions of fine IP interfere with anthropogenic pollutants.