Stable carbon isotopic compositions and source apportionment of the carbonaceous components in PM2.5 in Taiyuan, China

To determine the stable carbon isotopic compositions (613C) and source apportionment of carbonaceous components in Taiyuan, PM2.5 samples were collected using medium flow samplers (TH-150C) during 4 months in 2014. The 613C values of organic carbon (OC) and elemental carbon (EC) in PM2.5 were determined using an MAT-251 gas mass spectrometer with a dual inlet system. Moreover, 613CEC values from industrial and domestic coal combustion were synchronously measured. In March, May, August, and December, the mean 613COC values were -23.9 +/- 0.9%o, -25.2 +/- 0.2%o, -25.3 +/- 0.6%o, and -22.9 +/- 1.0%o, respectively; the corresponding 613CEC values were -23.8 +/- 0.8%o, -24.2 +/- 0.5%o, -25.3 +/- 0.4%o, and -23.8 +/- 0.3%o; and the corresponding 613CTC values were -23.8 +/- 0.7%o, -24.8 +/- 0.2%o, -25.3 +/- 0.4%o, and -23.2 +/- 0.6%o. Notable differences were observed in temporal distributions of stable carbon isotopic compositions of OC, EC, and total carbon (TC). The heavier 613CEC values in December and March was caused by increased coal combustion and C4 plant burning during the heating season. The 613CEC value was heavier than the 613COC value in May, whereas the opposite was true in December. The 613COC value may have been changed in atmospheric reactions during secondary organic aerosols formation in May and photochemical aging in December. There was almost no difference between 613COC and 613CEC in March and August. Source apportionment suggest that the EC sources in Taiyuan during the 4 months were different. EC in March and December was mainly due to fossil fuels (93.8%) and C4 plant burning (6.2%), EC in May was mainly affected by industrial coal combustion (50.0%) and vehicle exhaust (50.0%), and EC in August was the comprehensive result of fossil fuels (63.6%) and charcoal burning (36.4%). These results may enhance understanding of the sources of carbonaceous components in fine particles and may provide valuable data for environmental management.