Atmospheric mineral particles collected at Qira in the Taklamakan desert, China

Aerosol particles were collected in the situation of the widespread dust suspension on 21 February 1991 at Qira in the southern edge of the Taklamakan Desert, western China. The collected particles were examined by a transmission electron microscope equipped with an energy-dispersive X-ray (EDX) analyzer in order to obtain the size and elemental composition of individual mineral particles. On the basis of EDX analyses for 386 particles, mineral particles were present in high number fractions (> 99%) of particles in the radius range of 0.1-4 mum. Particles mainly composed of silicates comprised 76% of mineral particles. Ca-rich particles were detected in 7% of all the particles. Ca in the particles would be present not only as CaCO3 but also as an internal mixture of CaCO3 and CaSO4. Particles containing halite (NaCl) were detected in number proportions of about 10% and were mainly present in the radius range of greater than or equal to 0.5 mum. Some halite particles would be modified by chemical reactions with sulfuric acid. (C) 2004 Elsevier Ltd. All rights reserved.