A comparative study of chemical databases for fine particle Chinese

A chemical database for PM2.5 and PM2.0 aerosols has been assembled for various sampling sites in China. The primarily urban sites, sampled from 1980 to 1993, include Beijing, Tianjin, Wuhan, Lanzhou, and Guangzhou. From 13 to 22 inorganic chemical elements were measured but few secondary and organic compounds. Previous source resolution studies are briefly summarized. A mass balance for the Beijing aerosol indicates that the three largest components are carbon-containing matter (similar to 50%), (NH4)(2)-SO4 (similar to 18%), and silicon compounds (similar to 12% expressed as silica). Silicon concentrations in Beijing and Lanzhou were 26-36 times higher than Los Angeles. The fine silicon probably comes from coal combustion, crustal sources, and rice straw burning, but the relative amounts are not certain. Mass concentration data for Chinese cities were compared among themselves and with downtown Los Angeles using scatter diagrams. Compositions of the Beijing aerosol were generally higher than Los Angeles; the Beijing PM2.0 mass in 1992-1993 was about 5 times that of Los Angeles PM2.5 in 1986. In addition to significant changes over the years measurements were made, seasonal and regional variations were also observed. Mass fractions of crustal elements Ca, Al, Mn, Ti, and Fe in Beijing were higher than Los Angeles, while Cu, Pb, Zn, Cr, and Ni were lower. For Lanzhou (1983) and Tianjin (1984), most PM2.5 components show higher concentrations than central Beijing.