Tests　for　individual　Sulfate－Containing　Particles　in　Urban　Atmosphere　in　Beijing

Thin film methods and X ray energy dispersive technique were applied to analyze sulfate-containing particles in Beijing in order to examine their features and sources. Atmospheric aerosol particles were collected on electron microscope meshes according to two size ranges: coarse particles (r>05 mu m) and fine particles (0.5 mu m>r>0.1 mu m) by using a two-stage impactor. It was found that more than seventy percent of the fine particles and about twenty percent of the coarse particles were sulfate-containing particles. These particles were formed mainly through heterogeneous nucleation. The element composition analyses revealed that the atmospheric aerosol particles in Beijing were dominated by crustal particles and construction dust.