中文关键词臭氧(O₃)浓度级别挥发性有机物(VOCs)污染特征来源解析 英文关键词ozone (O₃)concentration levelsvolatile organic compounds (VOCs)pollution characterizationsource apportionment

作者	单位	E-mail
王文美	天津大学环境科学与工程学院, 天津 300350	wwm_eia@126.com
高璟赟	天津市生态环境监测中心, 天津 300191	Aileen_jing@126.com
肖致美	天津市生态环境监测中心, 天津 300191
李源	天津市生态环境监测中心, 天津 300191
毕温凯	天津市生态环境监测中心, 天津 300191
李立伟	天津市生态环境监测中心, 天津 300191
杨宁	天津市生态环境监测中心, 天津 300191
徐虹	天津市生态环境监测中心, 天津 300191
孔君	天津市生态环境监测中心, 天津 300191

中文摘要 为深入了解挥发性有机物（VOCs）对臭氧（O₃）污染的影响，基于2019年夏季天津市O₃和VOCs高时间分辨率在线监测数据，对不同O₃浓度级别VOCs污染特征及来源进行分析.结果表明，2019年夏季天津市O₃浓度为优、良、轻度污染和中度污染时，VOCs浓度分别为32.94、38.10、42.41和47.12μg·m^-3.VOCs组分中烷烃、烯烃、炔烃和芳香烃浓度占比分别为61.72%~63.36%、14.96%~15.51%、2.73%~4.13%和18.53%~19.10%，其中烷烃在O₃浓度为良和轻度污染时占比略高，烯烃和炔烃在O₃浓度为优时占比最高，芳香烃在O₃浓度为中度污染时占比最高.浓度较高的VOCs物种主要为丙烷、乙烷、乙烯、甲苯、正丁烷、异戊烷、间/对-二甲苯、丙烯、乙炔、正己烷、异丁烷、苯、正戊烷、异戊二烯和1，2，3-三甲苯，其中异戊烷、正戊烷、苯、乙烯、丙烯、正丁烷和异丁烷浓度贡献随O₃浓度级别上升逐步增加，异戊二烯和1，2，3-三甲苯浓度贡献在轻中度污染时明显升高.烯烃和芳香烃对臭氧生成潜势（OFP）贡献较高，随着O₃浓度级别上升，烯烃对OFP贡献下降，芳香烃贡献上升.乙烯、丙烯、间/对-二甲苯、1，2，3-三甲苯、甲苯、异戊二烯、反-2-丁烯和顺-2-戊烯是影响臭氧生成的关键物种，其中1，2，3-三甲苯、异戊二烯、丙烯和乙烯对OFP的贡献比例在O₃为轻中度污染时明显增加.源解析结果显示，机动车排放源、溶剂使用源、LPG/汽油挥发源、燃烧源、石化工业排放源、天然源和其他工艺过程源是天津市夏季VOCs主要来源，随着O₃浓度级别上升，机动车排放源、LPG/汽油挥发源、石化工业排放源和天然源贡献逐渐增加，燃烧源和其他工艺过程源贡献总体下降，溶剂使用源贡献在轻中度污染时有所下降. 英文摘要 To further study the effect of volatile organic compounds (VOCs) on ozone pollution, the characteristics and sources of VOCs at different ozone (O₃) concentration levels were analyzed, using high-resolution online monitoring data obtained from Tianjin in the summer of 2019. Results showed that VOCs concentrations were 32.94, 38.10, 42.41, and 47.12 μg ·m^-3, when the O₃ concentration levels were categorized as excellent, good, light pollution, and moderate pollution, respectively. VOCs were composed of alkanes, alkenes, alkynes and aromatics, which accounted for 61.72%-63.36%, 14.96%-15.51%, 2.73%-4.13%, and 18.53%-19.10%, respectively, of VOCs concentrations at different O₃ concentration levels. Among them, the proportion of alkanes was slightly higher when O₃ concentration was categorized as good or light pollution, alkenes and alkynes accounted for the highest proportion when O₃ concentration was excellent, and the proportion of aromatics was highest during periods of moderate pollution. The main VOCs species were propane, ethane, ethylene, toluent, n-butane, isopentane, m/p-xylene, propylene, acetylene, n-hexane, isobutene, benzene, n-pentane, isoprene, and 1,2,3-trimethylbenzene. The concentration percentage of isopentane, n-pentane, benzene, ethylene, propylene, n-butane, and isobutane increased gradually as O₃ concentration increased. Significant increases in isoprene and 1,2,3-trimethylbenzene were observed during periods of light and moderate pollution. Alkenes and aromatics had higher ozone formation potential (OFP), and the contribution of alkenes to OFP declined as the O₃ level rose, whereas that of aromatics increased. Ethylene, propylene, m/p-xylene, 1,2,3-trimethylbenzene, toluene, isoprene, trans-2-butene, and cis-2-pentene were the key species for O₃ generation, and the contribution ratio of 1,2,3-trimethylbenzene, isoprene, propylene, and ethylene to OFP increased significantly during light or moderate O₃ pollution. Positive matrix factorization was applied to estimate the source contributions of VOCs. Automobile exhaust, solvent usage, liquefied petroleum gas (LPG)/gasoline evaporation, combustion, petrochemical industrial emissions, natural sources, and other industrial emissions were identified as major sources of VOCs in summer. As O₃ concentration level rose, the contribution percentage of automobile exhaust, LPG/gasoline evaporation, petrochemical industrial emissions, and natural sources increased gradually, whereas the contribution of combustion and other industrial emissions decreased overall. The contribution of solvent usage was lower when O₃ levels indicated light or moderate pollution than when it was good.

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