[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.

[Study on microbial diversity and community in Miaoergou snow of East Tianshan Mountains and their relation to climatic and environmental changes].

The different depth snow samples were collected from the Miaoergou glacier in East Tianshan Mountains regions, China. Total bacteria counts were established by 4',6- diamino-2-phenylindole (DAPI). Both culture-dependent and culture-independent methods, denaturing gradient gel electrophoresis (DGGE), were used to examine the bacterial diversity and community structure. The microbial abundance and diversity index have a close relationship with mineral particle concentration. These mineral particles, such as Ca2+ , Mg2+, and Cl- etc, are good indicators of climate and environment. The 16S rDNA gene both of cultured bacteria and DGGE band sequenced belong to following groups: proteobacteria (alpha-, beta-, gamma-), Cytophaga- Flavobacterium-Bacteroides (CFB), High GC and Low GC. Among these, Proteobacteria and CFB are dominant groups. Compare with bacteria revealed from ice and snow in Qinghai-Tibet Plateau, South Pole and North Pole which have been reported, Paracoccu sp. and Aquasalina sp. are especially exist in this study area as far as we know. The microbial abundance and community structure are all changed obviously in different depth snow samples. It indicates that the snow bacteria community is influenced by many factors. The results show that because the special geographical position of the East Tianshan Mountains, microorganism in ice and snow of this area has its particularity.