| COVID-19疫情期间雄安地区VOCs的变化特征、臭氧生成潜势及来源解析 |
| 摘要点击 2598 全文点击 689 投稿时间：2021-06-30 修订日期：2021-08-30 |
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| 中文关键词 雄安 挥发性有机物(VOCs) 源解析 正交矩阵因子分解模型(PMF) 新冠肺炎疫情(COVID-19) 臭氧生成潜势(OFP) |
| 英文关键词 Xiong'an volatile organic compounds (VOCs) source apportionment positive matrix factorization (PMF) COVID-19 ozone formation potential(OFP) |
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| 中文摘要 |
| 利用挥发性有机物（VOCs）在线监测数据对新冠肺炎疫情（COVID-19）期间（2019年12月25日~2020年2月24日）雄安地区环境空气中VOCs进行监测，探讨了疫情防控前、后VOCs的变化特征、臭氧生成潜势及来源解析.结果表明，疫情防控后φ（TVOCs）平均值为45.1×10-9，约为疫情防控前φ（TVOCs）90.5×10-9的一半，芳香烃、卤代烃和OVOCs体积分数下降幅度超过60%.VOCs构成发生了较大变化，烷烃贡献率由37.6%增加至53.8%，芳香烃和卤代烃贡献率由13.3%和12.0%降低为7.5%和7.8%.疫情防控前、后体积分数前10物种有7种相同，主要为低碳烷烃、烯烃和醛酮类.疫情防控后二氯甲烷和三氯甲烷等卤代烃及苯系物下降幅度超过70%，具有机动车尾气示踪作用的甲基叔丁基醚体积分数下降超过60%.疫情防控前、后OFP分别为566 μg·m-3和231 μg·m-3，疫情防控后各类VOCs的OFP下降幅度均大于30%.芳香烃OFP贡献率在疫情防控后明显下降；疫情管控前、后烯炔烃OFP保持高贡献率，是雄安地区未来O3控制关键物种.源解析结果表明，疫情防控后溶剂使用源对TVOCs的贡献率从24%降低到9%，机动车尾气源在疫情防控前、后贡献率分别为21%和18%.疫情防控后背景源、油气挥发源和燃烧源的贡献率由6%、14%和13%升高为13%、34%和24%.观测点在疫情防控前受到了阵发性工业源VOCs排放的影响，疫情防控后停止排放，其贡献率由疫情防控前22%降低为防控后1%.工业源、溶剂使用源、机动车尾气源和燃烧源浓度在疫情防控后分别下降97%、82%、61%和15%，背景源浓度保持稳定，油气挥发源浓度增加7%.雄安地区未来VOCs控制除了管控工业和交通活动，也要加强对油气挥发源的防控. |
| 英文摘要 |
| Many restrictive measures were implemented in China from January-February 2020 to control the rapid spread of COVID-19. Many studies reported that the COVID-19 lockdown impacted PM2.5, SO2, volatile organic compounds (VOCs), etc. VOCs play important roles in the production of ozone and PM2.5. Ambient VOCs in Xiong'an were measured from December 25, 2019 to January 24, 2020 (prior to epidemic prevention, P1) and from January 25, 2020 to February 24, 2020 (during epidemic prevention, P2) through a VOCs online instrument. In the study, VOCs characteristics and ozone generation potential (OFP) of ambient VOCs were analyzed, and source apportionment of VOCs were analyzed by using Positive Matrix Factorization (PMF). The results showed that φ(TVOCs) during epidemic prevention and control was 45.1×10-9, which was approximately half of that before epidemic prevention and control (90.5×10-9). The chemical composition of VOCs showed significant changes after epidemic prevention and control, the contribution rate of alkanes increased from 37.6% to 53.8%, and the contribution rate of aromatic hydrocarbons and halogenated hydrocarbons decreased from 13.3% and 12.0% to 7.5% and 7.8%, respectively. Aromatic hydrocarbons, halogenated hydrocarbons, and OVOCs decreased by more than 60%. Seven types of the top ten species were the same before and during the epidemic prevention and control, mainly low-carbon alkanes, olefins, aldehydes, and ketones. Dichloromethane, trichloromethane, and BTEXs decreased significantly. The OPP was 566 μg·m-3 and 231 μg·m-3 in P1 and P2, respectively. The OPP of VOCs decreased by more than 30%. The proportion of OFP contribution of aromatic hydrocarbons decreased significantly after the epidemic prevention and control, and the proportion of OFP contribution of alkanes and alkynes increased significantly. Positive matrix factorization (PMF) was then applied for VOCs sources apportionment. Six sources were identified, including background sources, oil-gas volatile sources, combustion sources, industrial sources, solvent use sources, and vehicle exhaust sources. The results showed that after the epidemic prevention and control, the contribution rate of solvent use sources to TVOCs decreased from 24% to 9%. The contribution rates of background sources, oil-gas volatile sources, and combustion sources increased from 13%, 34%, and 24% to 6%, 14%, and 13%, respectively. The relative contributions of vehicle exhaust sources before and after epidemic prevention and control were 21% and 18%, respectively. The observation points were affected by the emission of VOCs from paroxysmal industrial sources before the epidemic prevention and control. The emission was stopped after the epidemic prevention and control, and its contribution rate was reduced from 22% before the epidemic prevention and control to 1%. The concentrations of industrial sources, solvent sources, motor vehicle tail gas sources, and combustion sources decreased by 97%, 82%, 61%, and 15%, respectively, after the epidemic prevention and control. The concentration of background sources remained stable, and the concentration of oil and gas volatile sources increased by 7%. The control of production and traffic activities cannot reduce the emission of VOCs from oil and gas volatile sources, which is the focus of VOCs control in Xiong'an. |
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