Source apportionment of carbonaceous aerosols in diverse atmospheric environments of China by dual-carbon isotope method

Abstract

Carbonaceous aerosols are major components in PM2.5 of both polluted and clean atmosphere. Accurate source apportionment of carbonaceous aerosols may support effective PM2.5 control. Dual-carbon isotope method (14C and 13C) was adopted to identify the contribution of three main air pollution sources biogenic and biomass (fbb), liquid fossil (fliq.fossil) and coal (fcoal). The aerosol samples were collected at three types of sites with distinctly different degree of air pollution: urban, rural and regional background. The seasonal variation of source apportionment of the carbonaceous aerosols in urban Beijing was discussed. Modern biogenic and biomass made an absolute dominance of 92.9 ± 0.5% contribution to the carbonaceous aerosols at the background site Mt. Yulong due to long-range transport from Southeast Asia. The three main sources contributed jointly to the atmospheric carbonaceous aerosols at the rural site Wangdu and the urban site Beijing. The biogenic and biomass source was the major contribution in summer (47.0 ± 0.3%) and autumn (49.3 ± 0.3%) of Beijing, while coal source increased from summer (26.8 ± 13.8%) to autumn (34.7 ± 11.5%). Heating significantly increased the coal source to the dominant contribution (47.0 ± 16.9%) in winter of Beijing. Separate day and night time coal contributions were used to evaluate the two origins of coal combustion: industrial use vs. residential use. The results of source apportionment for carbonaceous aerosols provide scientific support for the prevention and control of air pollution.