【摘要】 为探讨常州冬季大气气溶胶中类腐殖质（HULIS）的昼夜变化特征,在常州市城郊于2017年1月1日～2月28日采集了64个细颗粒物(PM_2.5)样品,分析获取了类腐殖碳（HULIS-C）的浓度和光学变化特征.冬季PM_2.5昼夜平均质量浓度分别为122. 60μg·m^-3和111. 72μg·m^-3,HULIS-C的昼夜平均质量浓度分别为4. 18μg·m^-3和3. 74μg·m^-3,白天均高于夜晚.紫外光谱分析结果表明,HULIS/WSOA（水溶性有机质）于250 nm处的吸光度比值（昼:77%,夜:75%）明显大于HULIS-C/WSOC（水溶性碳）的浓度比值（昼:51%,夜:50%）,表明较多的高紫外吸收物质和多聚共轭芳香结构存在于HULIS中;昼夜HULIS在250 nm和365 nm光下的吸光度比值（E250/E365）和特征紫外吸光度（SUVA280）的差异小,说明HULIS在芳香度和分子量上昼夜差异小,且昼夜HULIS化学性质及组成相近;进一步分析了HULIS的光吸收效率（MAE365）和光吸收指数（AAE300-400）,发现昼夜没有明显差异.此外,通过HULIS-C和PM_2.5中其他化学组分的相关性分析,定性了解常州市冬季HULIS的主要影响因素,HULIS-C来源上受到了生物质燃烧、化石燃料燃烧、工厂排放以及二次生成的共同影响;而昼夜之间对比表明,昼间HULIS主要受到二次生成的影响,而夜间HULIS来源上除受到白天二次生成影响外,也受到了一次燃烧排放的影响.更多还原

【Abstract】 To investigate the characteristics of diurnal variation of humic-like substances（ HULIS） in atmospheric aerosols during winter in Changzhou,a total of 64 fine particle( PM_2.5) samples were collected from January 1 to February 28,2017. In this study,the concentration as well as light absorption parameters of humic-like substances of carbon（ HULIS-C） were examined. The results showed that the average day PM_2.5 and HULIS-C concentrations were 122. 60 μg·m^-3 and 4. 18 μg·m^-3,respectively,slightly higher than those( 111. 72 μg·m^-3 and 3. 74 μg·m^-3) at night. Via UV-vis analysis,we found that the ratios of absorbance at 250 nm（ A250） of HULIS and WSOA（ day: ～ 77%,night: ～ 75%） were significantly higher than the concentration ratios of HULIS-C and WSOC（ day: ～ 51%,night: ～ 50%）,indicating that more UV-absorbing substances and poly-conjugated aromatic structures exist in HULIS. The daytime E250/E365 and SUVA280 in HULIS were close to the nighttime ones,indicating that there was no obvious difference between day and night in HULIS with reference to aromaticity and molecular weight. There were no significant differences in MAE365 and AAE300-400 of HULIS between day and night. In addition,to obtain the main influencing factors of HULIS in winter in Changzhou,the correlation analysis of HULIS-C and other chemical components were conducted. The results show that biomass burning,fossil fuel combustion,factory emissions,and especially secondary formation,were the main influencing factors. Moreover,daytime HULIS were mainly influenced by secondary reaction of anthropogenic precursor contaminants,while nighttime HULIS were affected not only by secondary formation by but by also primary combustion emissions.更多还原