LAUSR

Abstract The goal of this study was to identify the relative contribution of fossil and non-fossil contributions to PM2.5 carbonaceous aerosols (CAs) in PM2.5 pollution events. To achieve this, the pollution characteristics and source apportionments of CAs using radiocarbon (14C) and organic tracers (anhydrosugar) were determined during a long-lasting winter haze episode (Jan. 13–24, 2018) in Xiangyang, central China. Non-fossil sources (biofuel, biomass burning, and biogenic emissions) contributed 74 ± 3% and 35 ± 2% to organic carbon (OC, 20.7 ± 6.79 μg/m3) and elemental carbon (EC, 6.48 ± 1.79 μg/m3), respectively. During the winter haze episode, CAs were derived from primary biofuel and biomass burning-derived OC (POCbb, 27.3 ± 4%), secondary biofuel and biomass burning-derived OC (SOCbb, 26.7 ± 5%), fossil sources-derived EC (ECf, 15.4 ± 3%), secondary fossil sources-derived OC (SOCf, 14.7 ± 1%), biofuel and biomass burning-derived EC (ECbb, 8.4 ± 2%), primary fossil sources-derived OC (POCf, 5.5 ± 1%), and secondary biogenic sources-derived OC (SOCbio, 2.0 ± 1%). Biofuel and biomass burning contributed more to PM2.5 pollution compared to traffic exhaust, which indicated that the public and government should pay attention to control biofuel and biomass burning in Xiangyang, central China.