生物质燃烧源类腐殖质的臭氧老化特征

针对生物质燃烧排放类腐殖质（BC-HULIS）的臭氧（O₃）氧化开展模拟研究，利用总有机碳分析仪（TOC）、紫外-可见吸收光谱（UV-vis）、荧光激发发射矩阵光谱结合平行因子分析（EEM-PARAFAC）以及傅里叶变换红外光谱（FTIR）表征老化前后HULIS的光学性质和化学结构变化.研究表明，经臭氧氧化后BC-HULIS占相应的水溶性有机碳（WSOC）的比例降低，表明部分HULIS发生降解生成水溶性小分子化合物.此外经O₃老化后，HULIS的质量吸收指数（MAE₃₆₅）和芳香性指数（SUVA₂₅₄）分别从1.8~2.7和4.2~5.0m²/gC下降到1.1~1.3和3.7~4.1m²/gC，表明老化后HULIS的吸光能力和芳香度均呈现降低.EEM-PARAFAC解析结果显示，BB-HULIS中荧光发色团主要由类蛋白荧光组分（C2）和类腐殖质荧光组分（C1、C3、C4）组成.O₃老化后，BB-HULIS的总荧光强度显著降低，两种性质的荧光组分相对含量和荧光参数发生显著变化，如老化后HULIS中类腐殖质荧光组分的相对含量和腐质化指数（HIX）均显著高于老化前样品，表明老化过程发生类蛋白的降解和类腐殖质的聚合.另外，FTIR分析结果显示O₃老化后含氧官能团含量显著增强，表明了O₃老化对HULIS官能团的影响.

Changes in optical properties and chemical functional groups of humic substances emitted from biomass combustion with O3 oxidation

Biomass combustion (BC) is an important source of humic-like substances (HULIS) in atmospheric aerosol, and the oxidation process has a significant impact on the optical properties and chemical structures of BC-HULIS. This study focused on the changes in primary BB-HULIS due to ozone (O₃) oxidation and the optical properties and chemical structure of HULIS before and after oxidation were characterized with the total organic carbon (TOC) analyzer, UV-Vis spectroscopy, Excitation-Emission Matrix coupled with parallel factor analysis (EEM-PARAFAC) and Fourier transform infrared spectroscopy (FTIR). The results showed that the relative contents of HULIS in the corresponding water-soluble organic carbon (WSOC) decreased with O₃ oxidation, suggesting the transformation of HULIS into water-soluble low molecular weight compounds. Furthermore, mass absorption efficiency (MAE₃₆₅) and aromatic index (SUVA₂₅₄) of HULIS decreased from 1.8~2.7m²/gC and 4.2~5.0m²/gC to 1.1~1.3m²/gC and 3.7~4.1m²/gC, respectively, indicating that both the absorption capacity and aromaticity of HULIS declined with O₃ oxidation. The fluorescent components in BC-HULIS were mainly composed of protein-like compounds (C2) and humic-like substances (C1, C3, C4). After O₃ oxidation, the total fluorescence intensities of BC-HULIS weakened greatly, and the relative contribution of two types of fluorophores and fluorescence index were all significantly changed. For instances, the relative contents of humic-like components and the humidification index (HIX) of BC-HULIS after O₃ oxidation were obviously higher than those before O₃ oxidation, suggesting the degradation of protein-like compounds and the aggregation of humic-like substances during the O₃ oxidation process. In addition, FTIR results showed that the oxygen-containing functional groups were markedly enhanced after O₃ oxidation, indicating effects of O₃ oxidation on the chemical functional groups of BC-HULIS.