薪柴燃烧溶解性棕色碳排放特征及光学性质

对农村薪柴（杨木和毛竹）燃烧排放的4类溶解性棕色碳（BrC）组分，包括水溶性有机物（WSOM）、水溶性类腐殖质（HULIS_WS）、碱溶性有机物（ASOM）和碱溶性类腐殖质（HULIS_AS）的组成特征和光学性质进行了初步研究.结果显示，薪柴燃烧排放出大量的BrC，其中BrC_T（WSOM+ASOM）占烟气PM_2.5质量的46%~56%，排放因子为（7.5~16）g/kg.HULIS是薪柴燃烧排放BrC的重要组分，占BrC_T的44%~46%.4类BrC的特征吸收指数（SUVA₂₅₄）、光吸收效率（MAE₃₆₅）和Ångström指数（AAE）值分别为1.9~4.0m²/g、0.4~2.1m²/g和6.2~11.1，说明薪柴燃烧排放BrC具有较高的芳香度、较强的光吸收能力且其光吸收具有较强的波长依赖性.三维荧光光谱分析结果显示，薪柴燃烧排放BrC主要以类蛋白荧光物质组成为主，这与雨水和大气气溶胶中水溶性BrC以类腐殖质荧光物质组成为主的特征存在显著差异.相关性分析结果显示，BrC的MAE₃₆₅与HIX和SUVA₂₅₄呈现显著的正相关性，与E₂/E₃、FI、BIX和β：α呈现显著的负相关性，说明薪柴燃烧排放BrC的光吸收特性与其芳香性、腐殖化程度、自生源贡献和新鲜度等紧密相关.本研究结果有助于进一步认识生物质燃烧BrC的排放特征，为探索大气BrC的来源和环境效应提供数据基础和科学依据.

Emission characteristics and optical properties of extractable brown carbon from residential wood combustion

The study was aimed to investigate the emission characteristics and optical properties of primary brown carbon (BrC), including water-soluble organic matters (WSOM), water-soluble humic like substances (HULIS_WS), alkaline-soluble organic matters (ASOM), alkaline-soluble HULIS (HULIS_AS), emitted from household residential wood combustion. The results showed that residential wood combustion emitted large amounts of BrC. Among them, BrC_T (WSOM + ASOM) were observed to make up 46%~56% of total smoke PM_2.5 mass, and the emission factors of them were 7.5~16g/kg. HULIS were important light absorber in primary BrC, which accounted for 44%~46% of BrC_T. The SUVA₂₅₄, MAE₃₆₅ and AAE values for primary BrC were 1.9~4.0m²/g, 0.4~2.1m²/gand 6.2~11.1, respectively, indicating that the primary BrC emitted from wood combustion exhibited high aromaticity, strong light absorbing capacity and its light absorption presented strong wavelength dependence. 3DEEM results showed that the protein-like substances were dominant fluorophores for primary BrC fractions. It was significantly different from the fluorescent characteristics for WSOM in rainwater and atmospheric aerosols, in which the humic-like substances were predominant fluorophores. The correlation analysis revealed that MAE₃₆₅ present strong positive correlations with HIX and SUVA₂₅₄, while strong negative correlations were found with E₂/E₃, FI, BIX and β:α. It implied that the light absorption of primary BrC emitted from residential wood combustion were greatly related to their aromaticity, humification degree, autochthonous and freshness characteristics. The results obtained in this study are helpful to better understand the emission characteristics of BrC from BB, and also can provide such deep insight into the sources and environment effects of atmospheric BrC.