资源环境科技发展态势分析平台

Brown carbon (BrC) affects the Earth's radiative balance due to its strong light absorption at short wavelengths. A custom-made combustion chamber was used to simulate biomass and coal burning and to investigate the emission characteristics of BrC absorption. Absorption angstrom ngstrom exponents (AAEs) at the wavelength pair of 370 and 880nm ranged from 1.19 to 3.25, suggesting the possible existence of BrC in biomass- and coal-burning emissions. Based on the assumption that AAE(BC)=1.0, BrC from biomass burning contributed to 41-85% of the total particles light absorption at 370nm, which is much higher than that from coal burning (15-18%). The estimated absorption emission factors of BrC at 370nm for biomass and coal burning were 15-47 and 2-13m(2)/kg, respectively. A 10x10km gridded BrC optical emission inventory for biomass and coal burning in China for 2015 was developed based on the measured absorption emission factors of BrC values and high-resolution activity data. The total annual BrC absorption cross section emissions from biomass and residential coal burning were 4,194Gm(2) (relative uncertainty at the 95% confidence level of -33.2, 41.2%) and 615Gm(2) (-39.3, 40.1%), respectively. These results should be useful for improving estimates of the radiative effects of BrC in China.