基于2021年6月16-26日济南市一次典型的臭氧(O3)污染过程,研究了不同污染时期(清洁期(CP),污染上升期(PRP),重污染期(HPP),分析了城市区域的污染衰退期(PDP)。采用正矩阵分解(PMF)和基于观测的模型(OBM)来识别VOCs的主要来源,O3生产机制,敏感物种。结果表明,市区HPP期ρ(O3-8h)平均值为(246.67±11.24)μg·m-3,ρ(O3-1h)峰值为300μg·m-3。VOCs的体积分数和NO2浓度受行星边界层和风速降低的影响,分别比其他三个时期高76.99%-145.36%和127.78%-141.18%,分别,是O3污染加剧的主要原因。烷烃,含氧挥发性有机化合物(OVOCs),卤代烃占43.81%,20.98%,城市地区的VOCs占17.43%,分别。在HPP期间,它们都表现出显著的增长,用丙酮,丙烷,乙烷是每个阶段中体积最高的三个物种,异戊烷在HPP期间表现出最高的生长。烯烃,烷烃,芳烃占40.19%,28.06%,臭氧产生潜力(OFP)的21.92%。1-丁烯,甲苯,异戊烷,异戊二烯是OFP含量较高的物种。异戊二烯在PRP阶段的OFP最高,和1-丁烯在HPP阶段具有最高的OFP。异戊烷的体积分数显著增加OFP。VOCs与CO的相关系数初步表明机动车尾气和油气挥发是HPP期VOCs的主要来源。进一步使用PMF表明溶剂使用来源,燃烧源,机动车尾气+油气挥发源,工业排放源,植物来源是城市地区VOCs的重要来源。HPP时期机动车尾气+油气挥发源对VOCs的贡献为其他时期的3.09-14.72倍。溶剂使用来源对VOC的贡献比CP和PRP时期高约2.50倍。VOCs体积分数增加的主要来源是机动车尾气,油气挥发源,和溶剂使用来源。潜在来源和浓度权重分析发现,VOCs也受到东北向滨州和东营的VOCs传播的影响。OBM结果表明,城市地区O3形成的主要途径是过氧化物羟基自由基(HO2·)和甲基过氧化物自由基(CH3O2·)与NO的反应。HPP阶段[P(O3)净]臭氧净生成速率为24×10-9h-1。根据灵敏度实验结果,1-丁烯的烯烃组分,丙烯,顺式-2-丁烯,乙烯是O3生产的主要物种。
Based on a typical ozone (O3) pollution process in Jinan City from June 16 to 26, 2021, the variation characteristics of O3 and its precursor volatile organic compounds (VOCs) during different pollution periods (clean period (CP), pollution rise period (PRP), heavy pollution period (HPP), and pollution decline period (PDP)) in the urban area were analyzed. Both positive matrix factorization (PMF) and an observation-based model (OBM) were used to identify the main sources of VOCs, O3 production mechanisms, and sensitive species. The results showed that the average value of ρ(O3-8h) during the HPP period in the urban area was (246.67±11.24) μg·m-3, and ρ(O3-1h) had a peak value of 300 μg·m-3. The volume fractions of VOCs and NO2 concentration were affected by the decrease in planetary boundary layer and wind speed, which were 76.99%-145.36% and 127.78%-141.18% higher than those in the other three periods, respectively, and were the main reasons for the aggravation of O3 pollution. Alkanes, oxygenated volatile organic compounds (OVOCs), and halogenated hydrocarbons accounted for 43.81%, 20.98%, and 17.43% of VOCs in urban areas, respectively. All of them showed significant growth during the HPP period, with acetone, propane, and ethane being the top three species by volume in each stage and isopentane showing the highest growth during the HPP period. Alkene, alkanes, and aromatic hydrocarbons accounted for 40.19%, 28.06%, and 21.92% of the ozone generation potential (OFP). 1-butene, toluene, isopentane, and isoprene were the species with higher OFP. Isoprene had the highest OFP during the PRP phase, and 1-butene had the highest OFP during the HPP phase. The volume fraction of isopentane significantly increased OFP. The correlation coefficient between VOCs and CO preliminarily indicated that motor vehicle exhaust and oil and gas volatilization were the main sources of VOCs during the HPP period. Further use of PMF revealed that solvent use sources, combustion sources, motor vehicle exhaust+oil and gas volatilization sources, industrial emission sources, and plant sources were important sources of VOCs in urban areas. The contribution of motor vehicle exhaust+oil and gas volatilization sources in the HPP period to VOCs was 3.09-14.72 times higher than that in other periods. The contribution of solvent use sources to VOCs was approximately 2.50 times higher than that in the CP and PRP periods. The main sources of VOCs volume fraction increase were motor vehicle exhaust, oil and gas volatilization sources, and solvent use sources. Potential sources and concentration weight analysis found that VOCs were also affected by the transmission of VOCs to Binzhou and Dongying in the northeast direction. The OBM results indicated that the main pathway of O3 formation in urban areas was the reaction of peroxide hydroxyl radicals (HO2·) and methyl peroxide radicals (CH3O2·) with NO, and the net ozone generation rate during the HPP phase [P(O3)net] was 24×10-9 h-1. Based on the sensitivity experiment results, the alkene components of 1-butene, propylene, cis-2-butene, and ethylene were the dominant species for O3 production.