The characteristics of PM2.5 in Beijing, China

Weekly PM2.5 samples were simultaneously collected at a residential (Tsingh ua University) and a downtown (Chegongzhuang) site in Beijing from July 199 9 through September 2000. The ambient mass concentration and chemical compo sition of the PM2.5 were determined. Analyses included elemental compositio n, water-soluble ions, and organic and elemental carbon. Weekly PM2.5 mass concentrations ranged from 37 to 357 mug/m(3), with little difference found between the two sites. Seasonal variation Of PM2.5 concentrations was sign ificant, with the highest concentration in the winter and the lowest in the summer. Spring dust storms had a strong impact on the PM2.5. Overall, orga nic carbon was the most abundant species, constituting no less than 30% of the total PM2.5 mass at both sites. Concentrations of organic and elemental carbon were 35% and 16% higher at Tsinghua University than at Chegongzhuan g. Ammonium, nitrate and sulfate were comparable at the sites, accounting f or 25-30% of the PM2.5 mass. (C) 2001 Elsevier Science Ltd. All rights rese rved.