Airborne particulate study in five cities of China

Low-volume particulate samples (equivalent to PM10 size distributions) were taken during the fall and early winter of 1998–1999 in the cities of Dongying, Jinan, and Qingdao in Shandong Province, and in the independent districts of Shanghai and Beijing. X-ray diffraction and transmission analysis and polarizing optical microscopy were performed on the samples. The samples from all cities and districts contained the major components of quartz, feldspar, clays, calcium sulfates, and carbonates (except Qingdao). The Qingdao sample was surprising in that no carbonate components were observed. Carbonaceous matter dominated in all wintertime samples, but with a large variety of the mineral components also being present. It was also observed that some of the airborne calcium carbonate (calcite), an important fugitive dust constituent, reacted with sulfuric acid aerosols from industrial sources, to form two hydrated forms of calcium sulfate. The metastable carbonate, vaterite, was also observed in association with high-carbon samples, but itʹs formation as an in situ reaction product is uncertain.