我国机动车排放VOCs及其大气环境影响

挥发性有机化合物(volatile organic compounds,VOCs)作为大气中主要污染物之一,是O3和二次有机气溶胶(secondary organic aerosol,SOA)的重要前体物.为全面了解我国城市机动车排放VOCs对空气质量的影响,本文系统介绍了我国部分城市大气中VOCs的源解析最新成果,并分车型、分燃料综述了我国机动车VOCs的排放因子、成分谱及其对二次污染的贡献,以期为未来机动车VOCs排放和控制提供数据和理论支持.研究发现,机动车是我国城市大气VOCs的最大源,平均贡献率为36.8%;摩托车和轻型汽油车是主要排放车型.机动车尾气排放VOCs对城市O3和SOA生成都有重要贡献,随着排放标准提升和运行工况改善,机动车排放因子和臭氧生成潜势(ozone formation potentials,OFPs)明显降低,成分谱以芳香烃和烯烃等活性组分为主,对二次污染的贡献较大.

VOCs Emission from Motor Vehicles in China and Its Impact on the Atmospheric Environment

Volatile organic compounds (VOCs) are important precursors of O₃ and secondary organic aerosols (SOAs). In order to fully understand the impacts of VOCs from motor vehicles on urban air quality, the current state-of-the-art research results on source apportionment are systematically introduced. The contribution of VOCs from motor vehicles to secondary pollutants in China is further discussed. It was found that motor vehicle exhaust is the largest source of urban atmospheric VOCs, and the average contribution ratio is up to 36.8%, wherein motorcycles and light gasoline vehicles are the main emission sources. The results showed that VOCs from vehicles play an important role in O₃ and SOA formation in urban areas, whereas with the improvement of emission standards and operating conditions, the motor vehicle emission factors and ozone formation potentials (OFPs) are obviously reduced. Moreover, the composition profile of the exhaust is mainly composed of aromatic hydrocarbons and alkenes, which contribute more to secondary pollution. This work can aid in providing data and theoretical support for the control of VOCs from motor vehicles in the future.