[Characteristics of fly ash particles deposition in the snowpack of Laohugou Glacier no. 12 in western Qilian Mountains, China].

This research aimed to identify and characterize individual spherical fly ash particles extracted from surface snow at Laohugou Glacier No. 12, western Qilian Mountains, China. Characterization of the spherical particles (i. e. morphology, chemical composition and genesis) was obtained by scanning electron microscopy coupled with energy dispersive X-ray spectrometer (SEM-EDX). Spherical particles and agglomerates were identified according to their morphology in nine snow samples. Prevalent particle types in all samples were granular spherical particles, hollow spherical particles, and agglomerates. The vast majority of spherical particles in our samples had mostly smooth and glossy surfaces. Individual particle analyses of elemental composition showed that particles formed in combustion were mainly composed of silicon, aluminum and trace elements. On the basis of chemical information obtained from EDX, the fly ash particles deposited in the snow could be classified into three types, which were Si-dominant particles, Fe-dominant particles, and Ti-dominant spherical particles. Backward air mass trajectory and dispersion analysis suggested that the developed urban regions of central Asia and surrounding Yumen city contributed the primary fly ash particles from industrial combustion to the study site through the high-level atmospheric circulation.

[Mineral and elemental characteristics of microparticles with different size fraction in snowpits from Zadang Glacier].

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.