武汉军运会前后臭氧及其前体物的特征和来源

利用湖北省超级站2019年10~11月的臭氧、NO_x(=NO+NO₂)和102种VOCs物质的小时数据分析了军运会期间臭氧污染变化;基于DSMACC箱型模式模拟不同VOCs和NO_x浓度下臭氧的光化学生成敏感性;采用PMF模型对前体物VOCs进行源解析,并估算不同源类的臭氧生成潜势.结果显示,军运会保障前臭氧日最大8小时浓度(最大MDA8:219.51μg/m³)超过国家二级标准,保障期臭氧MDA8浓度(135.11μg/m³)明显下降,保障后浓度回升(140.98μg/m³).军运会保障前中期臭氧浓度的差异受气象条件影响更明显,而保障后臭氧浓度的上升主要是因为前体物浓度的大幅增加.根据DSMACC模拟的EKMA曲线,武汉市军运会期间臭氧的光化学生成主要受VOCs浓度变化的影响.进一步对VOCs进行源解析,结果显示,保障前VOCs对臭氧生成贡献较大的源类是燃烧源、石油化工和机动车,分别占23.0%、22.8%和22.5%;保障期间VOCs的主要来源是机动车(38.4%)和燃烧源(25.5%);保障后则主要是石油化工(32.6%)和燃料挥发(25.7%).三个阶段对比发现,军运会的保障方案对石油化工源减排效果明显,但对机动车和燃烧源排放的限制效果并不显著.武汉市应该更注重对燃烧、燃料挥发和机动车排放的治理.

Characteristics and sources of ozone and its precursors aroundthe Wuhan Military Games

The hourly data of ozone, NO_x (= NO + NO₂) and VOCs (102species) during October~November 2019 provided by Hubei Superstationwere used to analyze the variation characteristics of ozone pollutionduring the Wuhan Military Games (WMG). The photochemical regime of ozone was simulated based on DSMACC box model. The source apportionment of VOCs was conducted by PMF model, and the ozone formation potential of different VOCs sourcewas estimated. The results showed that the maximum daily 8-hour average ozone concentration (maximum MDA8:219.51μg/m³) exceeded the national level II standard before the military games. The MDA8 values (135.11μg/m³ on average) decreased significantly during the military games, and the concentrations (140.98μg/m³) rise after the WMG. The difference of ozone before and during the military games was mainly affected by meteorological conditions, and the increase of ozone after the WMG was mainly due to the significant increase of precursor emissions. The EKMA curve indicates that the photochemical formation of ozone was controlled by a VOC-limited regime during the study period. The VOCssources that contribute greatly to ozone formation before the military games were combustion, petrochemical industry and motor vehicles, accounting for 23.0%, 22.8% and 22.5%, respectively. The main sources of VOCs during the military games were motor vehicles (38.4%) and combustion (25.5%). While petrochemical industry (32.6%) and fuel volatilization (25.7%)were the main sources after the WMG. The results showed that the prevention strategies of the military games had a significant effect on the emission reduction of petrochemical industry, but the emission mitigation of motor vehicles and combustion was not significant. Wuhan should pay more attention to the control of combustion, fuel volatilization and motor vehicle emissions.