Multichannel characteristics of absorbing aerosols in Xuzhou and implication of black carbon.

Black carbon (BC) is an important component of atmospheric aerosols; BC aerosols are produced mainly by the incomplete combustion of carbon-containing substances, and they have important effects on climate change, the atmospheric environment, and public health. Most of the existing research has focused on the single-band measurement results of BC aerosols. However, each band offers different information regarding the optical absorption properties of aerosols, such as enhanced light absorption by brown carbon in the 370 nm band. To bridge this research gap, the present study used BC concentration data measured by an AE42 aethalometer to analyze the multiband pollution characteristics of BC aerosols in Xuzhou city in China. An aethalometer model was established to quantitatively describe the concentrations of BC produced by solid and liquid fuels, and a concentration-weighted trajectory analysis was used to analyze the potential sources of BC aerosols in Xuzhou and their contributions to the total BC. The following results were obtained. (1) The BC concentration was high in spring and winter and low in summer and autumn, and the diurnal variation showed bimodal characteristics. (2) The difference among the aerosol concentrations in the seven bands was larger in autumn and winter than in spring and summer, and the contribution of brown carbon in autumn and winter was greater than that in spring and summer. (3) In winter, the solid source (coal and biomass combustion) of BC accounted for a large proportion of the total BC. (4) A source analysis of BC pollution days and BC clean days indicated different sources of BC pollution in different seasons. The results of this study provide a theoretical basis and realistic guide for the prevention and control of atmospheric pollution in Xuzhou and are anticipated to be of great significance for improving the regional and global atmospheric environment.