机动车尾气和非尾气排放多环芳烃及其衍生物的影响因素研究进展

Research progress on the influencing factors of polycyclic aromatic hydrocarbons and derivatives from vehicle exhaust and non-exhaust emissions

机动车尾气排放多环芳烃(PAHs)及其衍生物主要源于化石燃料的不完全燃烧,排放特征随燃烧条件和燃料种类变化而有所不同.随着尾气排放控制标准日益严格和新能源汽车的逐渐普及,非尾气排放污染对交通大气污染的贡献逐年加大.因此,包括刹车磨损、轮胎磨损、道路扬尘再悬浮和路面磨损在内的非尾气排放过程作为城市环境PAHs的重要污染源,其占比不容忽视.机动车来源PAHs及其衍生物的排放特征主要受燃烧条件、路面条件和机动车部件材料种类等多种因素影响.本文对国内外现有的机动车尾气排放以及非尾气排放PAHs及其衍生物的数据进行了梳理和总结.总的来说,对于尾气排放,严格的排放标准导致PAHs及其衍生物排放量降低;冷启动、加速等工况下,发动机燃烧效率降低,排放量增大;柴油车排放量远高于汽油车;汽油直喷发动机比气道喷射发动机排放更高;车辆行驶里程增加排放量增加.且研究发现刹车片化学成分、制动情况、轮胎材料和路面条件等均会影响排放,具有高度的不确定性,有待进一步研究.本文旨在分析机动车来源PAHs及其衍生物在不同影响因素下的排放特征,为排放控制技术发展和政策标准制定提供科学依据.

Polycyclic aromatic hydrocarbons(PAHs) are a group of toxic organic compounds from vehicle emissions. Many PAHs are carcinogenic, teratogenic, mutagenic, and immunotoxic, causing a negative impact on human health and severe damage to the environment and ecosystems. Although PAH derivatives, including nitro-polycyclic aromatic hydrocarbons(NPAHs) and oxygenated polycyclic aromatic hydrocarbons(OPAHs), are one to three orders of magnitude lower in concentration than PAH parents, some components are far more mutagenic and carcinogenic than PAH parents. The PAHs and their derivatives in motor vehicle exhaust emission are mainly caused by the incomplete combustion of fossil fuels, and their emission characteristics vary with the combustion conditions and fuel compositions. With the increasingly strict control of exhaust emission standards and the gradual popularization of electric vehicles, non-exhaust emissions have become the main contributors to traffic air pollution. Therefore, as the main source of PAHs in an urban environment, non-exhaust emissions, including brake wear, tire wear, road dust resuspension, and road wear emissions, cannot be ignored in terms of their contribution proportion. The emission characteristics of PAHs and their derivatives from vehicles are mainly affected by many factors, such as combustion conditions, road conditions, and the types of motor vehicle parts and materials. This paper collates and summarizes the existing data on vehicle exhaust and non-exhaust emissions of PAHs and their derivatives at home and abroad. In general, for exhaust emission, stricter emission standards lead to lower emission of PAHs and their derivatives;under operating modes, including cold start and acceleration, the engine combustion efficiency is reduced, leading to an increase in emission;the emission of diesel vehicles is much higher than that of gasoline vehicles;gasoline direct injection(GDI)exhibits higher PAH emissions than port fuel injection(PFI);and emissions increase with increasing vehicle mileage. At present, studies on the non-exhaust emission of PAHs and their derivatives are lacking. Existing studies find that the chemical composition of brake pads, braking conditions, tire materials, and pavement conditions affect non-exhaust emissions, but these findings have a high degree of uncertainty and need further research. This paper is intended to analyze the emission characteristics of PAHs and their derivatives from motor vehicles under different influence factors to provide a scientific basis for developing emission control technology and formulating policy standards.