中国环境科学

作者：朱书慧, 来勇, 严仁嫦, 高雅琴, 沈建东, 吴宇航, 黄聪艳, 叶旭红, 金嘉佳, 林旭, 王蕴赟, 张天, 费罗兰, 帅启凡

单位：1. 上海市环境科学研究院, 国家环境保护城市大气复合污染成因与防治重点实验室, 上海 200233;2. 浙江省杭州生态环境监测中心, 浙江 杭州 310007

关键词：有机气溶胶,有机分子示踪物,藿烷,羟基羧酸,二羧酸

基金：国家重点研发计划(2023YFC3705201);国家自然科学基金资助项目(42307155)

Air quality in Hangzhou was greatly improved during the 19th Asian Games with the implementation of temporary emission control measures. Observation data collected at the Asian Games Core Supersite show that average concentration of PM2.5 during the Games declined by 18% and 71% compared with the periods before and after the Games, respectively. Among its major components, organic aerosols (OA) displayed largest decrease in average concentration by 32%. To further understand the chemical characteristics and formation variations of OA brought by emission reductions, a thermal desorption aerosol GC/MS (TAG) online system was adopted in this study to measure hourly concentrations of total 110organic molecular markers in OA at the same site. The results show that hopanes, which are mainly emitted from vehicles, dropped most significantly among primary organic molecular groups with a mass decrease ratio of 32%. The variations of αβ-norhanpe to EC and αβ-hanpe to EC mass ratios suggest that OA collected at the supersite was more influenced by diesel emissions before and after the Games. While during the Games, their mass ratios were closer to emission inventory obtained from gasoline vehicles, indicating that restriction measures executed in diesel vehicles remarkably lowered the concentration of primary OA. Among secondary organic molecular markers, hydroxyl-carboxylic acids and dicarboxylic acids were the two groups showing highest mass proportions in TAG-measured OA. Their average concentrations also decreased during the Games by 56% and 32%, respectively. Their correlations with other organic molecular groups in OA as well as volatile organic compounds (VOCs) in the gas phase suggest that dicarboxylic acids were formed via photochemical processing from various particular and gaseous precursors, including naphthalene-related, α-pinene-related, and isoprene-related secondary organic aerosol (SOA) tracers as well as VOC species such as aldehyde ketones, furans, terpenes. While hydroxyl-carboxylic acids were mainly secondarily produced from aromatic-related and α-pinene-related SOA tracers in the particle phase. The noticeable decreases in the concentrations of hydroxyl-carboxylic acids and dicarboxylic acids as well as their precursors during the Games imply that controlling anthropogenic VOCs emissions can effectively suppress the formation of secondary OA.

来源：2024年第11期

《中国环境科学》期刊编辑部

查看中国环境科学杂志2024年第11期