[Chemical Compositions in PM2.5 and Its Impact on Visibility in Summer in Pearl River Delta, China].

Aerosol samples of PM2.5 were collected simultaneously at 6 sites from five cities (Guangzhou urban, Conghua (suburban of Guangzhou), Foshan, Dongguan, Shenzhen and Zhubai) in Pearl River Delta region during the summer of 2010. The concentrations of organic carbon (OC), elemental carbon (EC) and water-soluble ions were determined by thermal/optical carbon analyzer and ion chromatography, respectively. The characteristics of PM2, OC, EC and ions, spatial distribution were discussed. Moreover, ambient light extinction coefficients were reconstructed by IMPROVE formula. The results showed that spatial distribution characteristics of PM2.5. and its chemical compositions were obviously different. The PM2.5 in Guangzhou, Foshan and Dongguan were higher than those in Zhuhai and Shenzhen. The contributions of (NH4)2SO4, OM, EC and NH4NO3 to ambient light extinction coefficient were 39%, 31%, 12% and 13%, respectively.