To compare the pollution characteristics of carbonaceous aerosol components in the atmosphere between urban and suburban areas, Chengdu City and Renshou County were selected as study areas from which 88 samples of PM2.5 during haze and non-haze periods were collected and analyzed. Quantification of mass concentrations of PM2.5, carbonaceous aerosol components[organic carbon (OC), elemental carbon (EC), and secondary organic carbon (SOC)], along with correlation analysis of OC and EC, and principal component analysis (PCA) of carbon components were carried out. The results show that pollutant concentrations during the haze period were higher than those during the non-haze period. The OC and EC for Chengdu City and Renshou County were positively correlated, with their correlation coefficients during the non-haze period higher than those during the haze period. The ratios of SOC/PM2.5 in Renshou County were higher than those in Chengdu City during the haze period. This indicates that secondary aerosols play a more important role in haze formation in Renshou than in Chengdu City. In contrast, the proportion of secondary aerosols during the non-haze period in Chengdu City was significantly higher, indicating that direct emissions are still the main cause of air pollution in Chengdu City. PCA results showed that PM2.5 formation in both Chengdu City and Renshou County was mainly due to coal burning, vehicle operation, and biomass burning.
Keywords: PM2.5; elemental carbon; haze; organic carbon; secondary organic carbon.