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Characterization of the light-absorbing properties, chromophore composition and sources of brown carbon aerosol in Xi'an, northwestern China
Yuan, Wei1,2; Huang, Ru-Jin1,3; Yang, Lu1; Guo, Jie1; Chen, Ziyi4; Duan, Jing1,2; Wang, Ting1,2; Ni, Haiyan1; Han, Yongming M.1; Li, Yongjie5
2020-04-30
摘要The impact of brown carbon aerosol (BrC) on the Earth's radiative forcing balance has been widely recognized but remains uncertain, mainly because the relationships among BrC sources, chromophores and optical properties of aerosol are poorly understood. In this work, the light absorption properties and chromophore composition of BrC were investigated for samples collected in Xi'an, northwestern China, from 2015 to 2016. Both absorption Angstrom exponent (AAE) and mass absorption efficiency (MAE) show distinct seasonal differences, which could be attributed to the differences in sources and chromophore composition of BrC. Three groups of light-absorbing organics were found to be important BrC chromophores, including compounds that have multiple absorption peaks at wavelengths > 350 nm (12 polycyclic aromatic hydrocarbons and their derivatives) and compounds that have a single absorption peak at wavelengths < 350 nm (10 nitrophenols and nitrosalicylic acids and 3 methoxyphenols). These measured BrC chromophores show distinct seasonal differences and contribute on average about 1.1 % and 3.3 % of light absorption of methanol-soluble BrC at 365 nm in summer and winter, respectively, about 7 and 5 times higher than the corresponding carbon mass fractions in total organic carbon. The sources of BrC were resolved by positive matrix factorization (PMF) using these chromophores instead of commonly used non-light-absorbing organic markers as model inputs. Our results show that vehicular emissions and secondary formation are major sources of BrC (similar to 70 %) in spring, coal combustion and vehicular emissions are major sources (similar to 70 %) in fall, biomass burning and coal combustion become major sources (similar to 80 %) in winter, and secondary BrC dominates (similar to 60 %) in summer.
DOI10.5194/acp-20-5129-2020
发表期刊ATMOSPHERIC CHEMISTRY AND PHYSICS
ISSN1680-7316
卷号20期号:8页码:5129-5144
通讯作者Huang, Ru-Jin(rujin.huang@ieecas.cn)
收录类别SCI
WOS记录号WOS:000531565400003
语种英语