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Aerosol samples were collected during the scientific expedition to Mt. Bogda in July-August, 2009. The major inorganic ions (Na+, NH4+, K+, Mg-2(+), Ca-2(+), Cl-, SO42-, and NO3-) of the aerosols were determined by ion chromatography. SO42-, NO3-, and Ca2+ were the dominate ions, with the mean concentrations of 0.86, 0.56, and 0.28 mu g m(-3), respectively. These mean ion concentrations were generally comparable with the background conditions in remote site of Xinjiang, while much lower than those in Urumqi. Morphology and elemental compositions of 1,500 particles were determined by field emission scanning electron microscopy equipped with an energy dispersive X-ray spectrometer. Based on the morphology and elemental compositions, particles were classed into four major groups: soot (15.1%), fly ash (4.7%), mineral particles (78.9%), and little other matters (0.8% Fe-rich particles and 0.5% unrecognized particles). Presence of soot and fly ash particles indicated the influence of anthropogenic pollutions, while abundance mineral particles suggested that natural processes were the primary source of aerosols over this region, coinciding with the ionic analysis. Backward air mass trajectory analysis suggested that Urumqi may contribute some anthropogenic pollution to this region, while the arid and semi-arid regions of Central Asia were the primary source.