| 郑州市O3攻坚期大气VOCs污染特征及来源解析 |
| 摘要点击 1657 全文点击 382 投稿时间：2023-10-19 修订日期：2024-01-22 |
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| 中文关键词 挥发性有机物（VOCs） 臭氧生成潜势（OFP） 羟基消耗速率（L·OH） 比值分析（RA） 正定矩阵因子分解（PMF）模型 来源解析 O3“攻坚期” |
| 英文关键词 volatile organic compounds （VOCs） ozone formation potential （OFP） hydroxyl consumption rate（L·OH） ratio analysis （RA） positive matrix factorization （PMF） model source apportionment campaign period of ozone |
| DOI 10.13227/j.hjkx.20241009 |
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| 中文摘要 |
| 采用GC5000在线气相色谱仪,在郑州市2022年5~9月臭氧（O3）“攻坚期”,对郑州市大气环境中挥发性有机化合物（VOCs）进行监测,分析了O3及其前体物与气象的关系,对比探究O3超标天和非超标天VOCs的污染特征,采取OFP和L·OH不同的VOCs活性评估方法对比分析了关键活性组分和物种,并重点利用比值分析（RA）和正定矩阵因子分解（PMF）受体模型研究了其来源贡献. 结果表明,郑州市6月和9月O3污染主要是在高温、低湿、强辐射和风速较小等恶劣气象条件作用下,叠加本地VOCs和NO2浓度的突出,造成O3超标且高值频发. 郑州市ρ（VOCs）均值为（68.3 ±18.4）μg·m-3,其中O3超标天为75.7 μg·m-3,高于O3非超标天（13.4 μg·m-3）,VOCs中OVOCs质量分数最高,为31.6%,其次是卤代烃、烷烃和芳香烃. VOCs中前15物种中主要为丙酮、乙烷、正丁烷、二氯甲烷、丙烷、异戊烷、甲苯、氯甲烷、1,2-二氯乙烷和乙炔等. VOCs日变化显示,早、晚高峰和夜间VOCs浓度突出,需重点关注. OFP和L·OH分别为（130.5 ±46.4）μg·m-3和（6.5 ±2.9）s-1,L·OH和OFP中OVOCs和烯烃贡献突出,前15物种中主要为：乙醛、异戊二烯、乙烯、间/对-二甲苯、甲苯、己醛、异戊烷、丙醛、丙烯和反-2-丁烯等,尤其在O3超标天中乙醛、异戊二烯、乙烯和己醛等物种贡献突出. 比值分析显示,郑州市5~9月B/T在0.05~5.3之间,均值为1.1 ±0.6,并且区域VOCs可能受老化气团控制较大,存在远距离传输. PMF模型解析表明,郑州市对VOCs浓度贡献影响较大的污染源是机动车尾气排放源和工业溶剂+二次转化源,贡献率分别为25.6%和25.8%. 在O3超标天时段,溶剂涂料使用源、油气挥发源、植物排放源和工业溶剂+二次转化源贡献率依次高于O3非超标天5.4%、4.7%、3.3%和0.7%. 研究显示,O3超标天需强化VOCs和NOx污染源的管理,削弱其对O3的生成贡献. |
| 英文摘要 |
| An online gas chromatograph （GC5000） was used to monitor the volatile organic compounds （VOCs） in the atmospheric environment of Zhengzhou City during the ozone campaign period from May to September of 2022. The relationship between O3 and its precursors as well as meteorology was analyzed and the pollution characteristics of VOCs during the O3 exceeding and non-exceeding the standard days were compared and explored. Different VOC activity evaluation methods of OFP and L·OH were utilized to compare and analyze the key active components and species and the ratio analysis （RA） and positive matrix factorization （PMF） analysis models were used to study the apportionment contribution of VOCs. The results showed that the O3 pollution in June and September in Zhengzhou was mainly due to the adverse meteorological conditions of high temperature and low humidity, strong radiation, and low wind speed, superimposed by the prominent concentrations of local VOCs and NO2, resulting in frequently high and excessive O3 occurrences. The VOCs concentration in Zhengzhou during the campaign period was an average of （68.3 ± 18.4） μg·m-3, whereas it was 75.7 μg·m-3 during O3 exceeding standard days and 13.4 μg·m-3 during O3 non-exceeding days, respectively. Among the VOC species, the OVOCs was 31.6%, accounting for the highest mass fraction, followed by halogenated hydrocarbon, alkane, and aromatic hydrocarbon, and the major species were ethane, n-butane, dichloromethane, propane, isopentane, toluene, chloromethane,1,2-dichloroethane, and acetylene. VOC diurnal variation indicated that the emission of VOC pollution sources in the morning, evening peak, and at night should be paid more attention. The contribution of VOCs to OFP during the campaign period was （130.5 ± 46.4） μg·m-3, and the L·OH was （6.5 ± 2.9） s-1, among which the top 15 species with high activity were primarily acetaldehyde, isoprene, ethylene, m/p-xylene, toluene, hexal, isopentane, propanal, propylene, trans-2-butene, etc. In particular, the contributions of acetaldehyde, isoprene, ethylene, and hexal species were prominent during the O3 exceeding days. Ratio analysis showed that the B/T ratio in Zhengzhou from May to September ranged from 0.05 to 5.3, with an average value of 1.1 ± 0.6, and the regional VOCs was mainly controlled by the aging air mass with possible long-distance transports. The analysis of the PMF model showed that the major pollution sources to VOC concentration in Zhengzhou were motor vehicle exhaust emission sources and industrial solvent and secondary conversion sources, contributing 25.6% and 25.8%, respectively. The contribution rates of solvent coating sources, oil and gas volatile sources, plant emission sources, industrial solvents, and secondary conversion sources during O3 exceeding days were 5.4%, 4.7%, 3.3%, and 0.7% higher than those during O3 non-exceeding days, respectively. The research showed that the management of VOCs and NOx pollution sources should be strengthened to reduce their contribution to the O3 generation when O3 exceeds the standard. |
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