[天津市PM-O复合污染特征及来源]

Xiao Zhi-Mei, Xu Hong, Gao Jing-Yun, Cai Zi-Ying, Bi Wen-Kai, Li Peng, Yang Ning, Deng Xiao-Wen, Ji Yun-Feng

Tianjin Eco-Environmental Monitoring Center, Tianjin 300191, China.

Tianjin Environmental Meteorological Center, Tianjin 300074, China.

Huan Jing Ke Xue. 2022 Mar 8;43(3):1140-1150. doi: 10.13227/j.hjkx.202108164.

The characteristics and sources of PM-O compound pollution were analyzed based on the high-resolution online monitoring data of PM, O and volatile organic compounds(VOCs) observed in Tianjin from 2017 to 2019. The results showed that total PM-O compound pollution was 34 days, which only appeared between March and September and slightly increased by year. The peak value of (O)(301-326 μg·m) appeared when (PM) ranged from 75 μg·m to 85 μg·m. During PM-O compound pollution, the average (VOCs) was 72.59 μg·m, and the chemical compositions of VOCs were alkanes, aromatics, alkenes, and alkynes, accounting for 61.51%, 20.38%, 11.54%, and 6.57% of VOCs concentration on average, respectively. The concentration of the top 20 species of VOCs increased, among which the proportion of alkane species such as ethane, n-butane, isobutane, and isopentane increased; the proportion of alkenes and alkynes decreased slightly; and the proportion of benzene and 1,2,3-trimethylbenzene of aromatic hydrocarbons increased slightly. The ozone formation potential(OFP) contribution of alkanes, alkenes, aromatics, and alkynes were 19.68%, 39.99%, 38.08%, and 2.25%, respectively; the contributions of alkanes, alkenes, and aromatics to secondary organic aerosol(SOA) formation potential were 7.94%, 2.17%, and 89.89%, respectively. Compared with that of non-compound pollution, the contribution of alkanes and aromatics to OFP increased 13.8% and 4.3%, and that to SOA formation potential increased 2.3% and 0.2%, respectively. The contribution of alkenes to OFP and SOA formation potential decreased 9.4% and 15.6%, respectively, and the contribution of alkynes to OFP increased 7.7% in compound pollution. The contributions of main species such as 1-pentene, -butane, methyl cyclopentane, isopentane, 1,2,3-trimethylene, propane, toluene, acetylene, -xylene, ethylbenzene, -ethyltoluene, and /-xylene to OFP increased, and that of isoprene to OFP decreased. The contribution of benzene, 1,2,3-trimethylbenzene, toluene, and -xylene to the potential formation of SOA increased during compound pollution. Positive matrix factorization was applied to estimate the contributions of sources to OFP and SOA formation potential in compound pollution, solvent usage, automobile exhaust, petrochemical industrial emission, natural source, liquefied petroleum gas(LPG) evaporation, combustion source, gasoline evaporation, and other industrial process sources were identified as major sources of OFP and SOA formation potential; the contributions of each source to OFP were 21.9%, 16.9%, 16.7%, 12.4%, 8.3%, 7.7%, 2.9%, and 13.2%, respectively, and to SOA formation potentials were 46.8%, 14.4%, 7.1%, 11.9%, 5.9%, 6.6%, 1.6%, and 5.7%, respectively. Solvent usage, automobile exhaust, and petrochemical industrial emissions were main sources for PM-O compound pollution.

基于2017年至2019年在天津观测到的PM、O和挥发性有机化合物（VOCs）的高分辨率在线监测数据，分析了PM-O复合污染的特征和来源。结果表明，PM-O复合污染总天数为34天，仅出现在3月至9月之间，且逐年略有增加。当PM浓度在75 μg·m至85 μg·m之间时，出现（O）（301 - 326 μg·m）的峰值。在PM-O复合污染期间，VOCs的平均浓度为72.59 μg·m，其化学组成为烷烃、芳烃、烯烃和炔烃，分别平均占VOCs浓度的61.51%、20.38%、11.54%和6.57%。VOCs浓度排名前20的物种浓度增加，其中乙烷、正丁烷、异丁烷和异戊烷等烷烃物种的比例增加；烯烃和炔烃的比例略有下降；芳烃中的苯和1,2,3 - 三甲基苯的比例略有增加。烷烃、烯烃、芳烃和炔烃对臭氧生成潜势（OFP）的贡献分别为19.68%、39.99%、38.08%和2.25%；烷烃、烯烃和芳烃对二次有机气溶胶（SOA）生成潜势的贡献分别为7.94%、2.17%和89.89%。与非复合污染相比，烷烃和芳烃对OFP的贡献分别增加了13.8%和4.3%，对SOA生成潜势的贡献分别增加了2.3%和0.2%。在复合污染中，烯烃对OFP和SOA生成潜势的贡献分别下降了9.4%和15.6%，炔烃对OFP的贡献增加了7.7%。1 - 戊烯、正丁烷、甲基环戊烷、异戊烷、1,2,3 - 三甲基苯、丙烷、甲苯、乙炔、二甲苯、乙苯、乙基甲苯和间/对二甲苯等主要物种对OFP的贡献增加，而异戊二烯对OFP的贡献下降。在复合污染期间，苯、1,2,3 - 三甲基苯、甲苯和二甲苯对SOA潜在生成的贡献增加。应用正矩阵分解法估算了复合污染中各源对OFP和SOA生成潜势的贡献，溶剂使用、汽车尾气、石化工业排放、天然源、液化石油气（LPG）蒸发、燃烧源、汽油蒸发和其他工业过程源被确定为OFP和SOA生成潜势的主要来源；各源对OFP的贡献分别为21.9%、16.9%、16.7%、1 — 9.4%和15.6%，对SOA生成潜势的贡献分别为46.8%、14.4%、7.1%、11.9%、5.9%、6.6%、1.6%和5.7%。溶剂使用、汽车尾气和石化工业排放是PM - O复合污染的主要来源。