Study On Emission Characteristics Of Vehicle Exhaust Particulate Matter In High Altitude Environment

In recent years,China's motor vehicle possession has shown a high growth trend,and its motor vehicle exhaust pollution has seriously affected the environmental air quality and human health.Motor vehicle exhaust pollution has become the primary source of atmospheric pollution in many economically developed regions.In the low-pressure and low-oxygen environment of Yunnan Plateau,the combustion characteristics of motor vehicles are much different than those in plain areas.In this study,tunnel sampling and bench test were used to collect the exhaust particles of motor vehicles in Yunnan Province,and 33 inorganic elements,carbon components,9water-soluble ions and 16 kinds of PAHs were analyzed.Explain and compare the differences in particle composition and compositional spectrum between particles with different particle sizes and between different oils.The localization emission spectrum of motor vehicle exhaust particulates in the plateau region of Yunnan Province was established,which provided basic data for the analysis of atmospheric particulate matter sources and health risk assessment in Yunnan Province.Studies have shown that the high-level components of vehicle exhaust emissions in the high-altitude environment of Yunnan Province are OC,EC,SO₄^2-,NO₃^-,Si and Al.These components are used in two different sampling methods:tunnel experiment and bench test.The mass concentration values have an order of magnitude difference.The PM_2.5.5 mass concentration range of diesel vehicles is 0.67-4.63mg/m³,the gasoline vehicle is 1.14-12.94mg/m³,and the PM_2.5.5 emitted by diesel vehicles is much higher than the gasoline vehicle mass concentration.The mass concentration of element,ion,OC and EC are 3.8 times,2.7 times,1.6 times and 1.7 times of that of gasoline vehicles respectively.Therefore,strengthening the quantity control of diesel vehicles is of great significance for the reduction of atmospheric fine particles.The mass concentration of each chemical component in the particles of different particle sizes is different,and the mass concentration in PM₁₀0 is greater than the mass concentration in PM_2.5.In the bench test of the plateau,the mass concentration of OC in PM_2.5.5 of motor vehicle exhaust emission is 1173.30-1923.50?g/m³,and the mass concentration of OC in PM_2.5.5 collected by tunnel experiment is 97.30-108.72?g/m³.In the same experiment in the plain area,the mass concentration of OC is high.It may be due to insufficient oxygen content in the plateau and insufficient fuel combustion under engine load,resulting in an increase in OC content.The divergence coefficient results show that the divergence coefficients of the inorganic component source spectrum and the PAHs component spectrum of different particle size of motor vehicle are 0.23 and 0.01,respectively,and the difference of source spectrum between different particle sizes is small.The PM_2.5.5 inorganic component source spectrum and the PAHs component spectrum divergence coefficient of different oil product types are 0.39 and 0.38,respectively,and the PM_2.5.5 source spectrum of different oil products is different.According to the difference calculation,BghiP can be used as the PAHs marker for gasoline vehicles,and Flu can be used as the indicator PAHs for diesel vehicles.