Microscopic Analyses of Insoluble Particles in an Ice Core of ürümqi Glacier No. 1: Quantification of Mineral and Organic Particles

Insoluble particle concentration in ice cores is commonly analyzed as a proxy for varia- tions in atmospheric mineral dust （aerosol concentration）. However, recent studies have revealed that the mineral dust is not only a constituent of the particles but that biogenic organic particles are also contained. We microscopically analyzed insoluble particles in a shallow ice core drilled on a mountain glacier, the Urumqi Glacier No. 1, in eastern Tienshan, China. We distinguished different morphological particles in the ice core and quantified them separately. Results showed that the insoluble particles in this ice core consisted mainly of mineral particles, amorphous organic particles, pollen, and micro- organisms. Mineral particles were the most dominant, accounting for approximately 67% of total par- ticles, and amorphous organic particles were the second most dominant, accounting for approximately 33% of the total. The annual variation in the particles for the last 11 years differed between mineral and amorphous organic particles. The results suggest that the total insoluble particle concentration in the ice core reflects not only the atmospheric mineral dust but also the organic particles blown from ground soil or produced by microbes on the glacial surface.

Characterization of contemporary aeolian dust deposition on mountain glaciers of western China

From 2008 to 2010, a total of 15 snow pit samples were collected from 13 mountain glaciers in western China. In this study these samples are used to determine the spatial distribution of insoluble particle concentrations and dust deposition fluxes in western China. The results show that the mass concentrations of insoluble particles exhibit high spatial variation and strongly decrease （by a factor of approximately 50） from the north （Tienshan Mountains） to the south （Himalayas）. However, the insoluble particles concentrations at the southeastern Tibetan Plateau （TP） sites are also high and ap- proximately 30 times greater than those in the Himalayas. The spatial distribution of the dust flux is similar to that of the mass concentrations; however, the high dust deposition rate in the southeastern TP is very significant as a result of the extensive snow accumulation （precipitation） in this region. The average sizes of the insoluble particles at each site generally exhibit bimodal distributions with peaks at approximately 5 μm and 10 μm, which can be explained as re- sulting from dust emissions from regional and local sources, respectively. The enrichment factors for most of the elements measured in insoluble particles are less than 10 at all of the study sites, indicating primarily crustal sources. However, the sites located in the peripheral mountains of western China, such as the Tienshan Mountains and the Himalayas, are characterized by high levels of certain enrichment elements （e.g., Cu, Zn, Cr, and V） indicative of sources related to the long-range transport of pollutants.