Source apportionment of black carbon aerosols in winter across China

Black carbon (BC) aerosols emitted from incomplete combustion of fossil fuels, biofuels, and biomass have significant effects on the environment and human health. Combustion-derived BC aerosols are an important component in haze pollution. High concentrations of BC aerosols were found in fine particulate matter (PM2.5) in China, and source apportionment was the strategy underpinning targeted mitigation actions. Here, we present a Bayesian statistical model, a three-dimensional array of a stable carbon isotope (813C) and the ratios of non-sea-salt K+ to BC (nss-K+/BC) and ABC/ACO that is a reasonably inexpensive and rapid way to constrain BC source apportionments. This study analyzed 551 daily PM2.5 samples collected in January 2018 in 18 large cities and at 1 remote site scattered across China. The results show that BC concentrations were generally higher in cities in northern China than they were in cities in southern China. Source apportionments indicate that BC in 44% of cities was mainly from liquid fuel combustion. In other sites, including 39% of cities, one suburban site, and one remote site, BC was mainly from biomass burning. These findings suggest that to improve air quality, the Chinese government should further strengthen controls on liquid fuel combustion and consider controlling biomass burning.