Measurement report: Optical and structural properties of atmospheric water-soluble organic carbon in China – insights from multi-site spectroscopic measurements

作者：Haibiao Chen, Caiqing Yan, Liubin Huang, Lin Du, Yang Yue, Xinfeng Wang, Qingcai Chen, Mingjie Xie, Junwen Liu, Fengwen Wang, Shuhong Fang, Qiaoyun Yang, Hongya Niu, Mei Zheng, Yan Wu, Likun Xue · 发表于：Atmospheric chemistry and physics · 年份：2025 · DOI：10.5194/acp-25-3647-2025 · 被引用次数：6 · 研究领域：Atmospheric chemistry and aerosols、Atmospheric Ozone and Climate、Spectroscopy and Laser Applications

Abstract. To understand the spatial variation of optical and structural properties of water-soluble brown carbon and its influencing factors in China, the light absorption, fluorescence, and Fourier transform infrared (FTIR) spectrum of water-soluble organic carbon (WSOC) in different regions of China are measured following the same analytical methods. The average light absorption coefficients and mass absorption efficiencies of WSOC at 365 nm (Abs365 and MAE365) rank from high to low as northwest China > southwest China > north China > east China > regional site, with higher values in northern China than southern China and regional sites and higher values in inland areas than coastal areas. The light absorption factors resolved by light absorption spectra-based positive matrix factorization model and the abundance of aromatic O−H and C=C functional groups determined by FTIR both indicate that aromatic compounds are significant light-absorbing substances in WSOC and have a significant impact on fluorophores. Multiple linear regression analysis shows that the fluorophores identified by fluorescence spectra combined with parallel factor analysis (PARAFAC) contribute to about 62 %–93 % of the WSOC light absorption at all sites, in which humic-like substance (HULIS) contributes the most, especially highly oxygenated HULIS (29 %–50 %) with long emission wavelengths. Combustion source emissions and atmospheric chemical processes have significant impacts on the WSOC ligh...