Study On Emission Characteristics Of Particulate Matters And Pollution Characteristics Of Volatile Organic Compounds From Vehicle Exhausts In Jinan

As the number of vehicles continues to grow rapidly,particulate matter and VOCs emitted by exhaust have become the main source of urban air pollution.However,there are limited studies on the concentration of particulate matter with different particle sizes and organic amine components directly emitted by vehicle exhausts.And the emission characteristics of VOCs from different sites in traffic environment are not clear.This study,represented by Jinan,a typical city with frequent regional air pollution,carried out three experiments related to vehicle exhausts.The first experiment studyed PM2.5 and PM10 mass concentration and PM0.01-1 number concentration of vehicle exhausts.The study found that ① The PM2.5 and PM10 mass concentrations and PM0.01～1o number concentration of vehicle exhausts are 0.350-5.132 and 1.708-7.862 mg·m-3,6.78-40.68×104 cm-3,respectively.The highest values all come from large diesel vehicles.②Operating conditions,vehicle size,fuel type,and emission standards all affect emissions of exhaust particulate matter.High idling mode>idling mode;large vehicles>medium-sized vehicles>small vehicles;diesel>92#gasoline>95#gasoline;National Ⅲ>National Ⅳ>National Ⅴ.In terms of mass concentration and number concentration in general of exhaust particulate matter,medium and large vehicles are about 2-5 times that of small vehicles;diesel vehicles are about 2 times that of gasoline vehicles;National Ⅲ standard gasoline vehicles are about 2-4 times that of National#and National Ⅴ.The second experiment studied the emission characteristics of fine particle organic amine components-aniline(AN)and dibutylamine(DBA)in PM2.5 emitted by vehicles.The study found that ① In terms of emission concentration,the average concentration of fine particle aniline in the exhaust of nine types of vehicles is 0.05-0.39 μg·m-3,and the maximum for a single vehicle is 0.71 μg·m-3;for fine particles dibutylamine,the average concentration is 0.00-2.08 μg·m-3,the maximum for a single vehicle is 3.74μg·m-3.②In terms of emission factors,the single-vehicle emission factor of fine particle aniline is 0.15-6.48 μg·km-1,and the fine particle dibutylamine is 0.02-36.69 μg·km-1.Diesel vehicles are higher than gasoline vehicles.The average emission factors of fine-particle aniline and dibutylamine for gasoline vehicles are about 0.52 and 0.07 μg·km-1,and for diesel vehicles are about 2.61 and 3.46 μg·km-1.③ Organic amines in vehicle exhausts related to the emission of NOx in the exhaustsThe third experiment studied the pollution characteristics of VOCs in urban site and roadside site affected by traffic sources.The study found that ① The greater the traffic volume,the higher the VOCs concentration.Roadside site are more polluted than urban site.According to "roadside site/city site(/ethane)",the volume concentration of roadside site is about 1.12 times that of urban site.The diurnal variation of urban site exhibits a double peak in the morning and evening with concentration-63.68 ppbv and～72.96 ppbv respectively;the concentration of roadside site during rush hours(84.73 ppbv)is higher than during non-rush hour traffic(68.27 ppbv).② The concentration ratio of VOCs is alkane>alkene>aromatic hydrocarbon>alkyne,and the proportion of aromatic hydrocarbon in roadside site is higher than that in urban site.③The total OFPs of VOCs at urabn site and roadside site are 137.00±58.94 ppbv and 250.53±50.20 ppbv,respectively,and the total LOH was 8.88±3.98 s-1 and 15.54±3.26 s-1,respectively.The atmospheric reactivity is slkene>alkane>aromatic hydrocarbon>acetylene,and alkene is the dominant species for ozone generation.From the perspective of ozone-controlled photochemical pollution,1-butene,p-m-xylene,3-methylpentane,ethylene,2-methylpentane,n-butane,propylene,toluene,cis-2-butene etc.are the key species.The corresponding suggestions can to a certain degree mitigate the air pollution from vehicle exhausts,including improving fuel quality,upgrading vehicle emission standards,optimizing the urban road system to reduce the frequent changes in the speed of vehicles on the actual road,strengthening the supervision and driving restrictions on medium and large vehicles,especially large diesel vehicles.This paper makes a comprehensive study on the pollution caused by vehicle exhausts,analyzes the emission characteristics of exhaust particles and fine-particle organic amines,as well as the pollution characteristics of VOCs in the ambient air affected by traffic sources.This provides data support and countermeasures for scientific prevention and control of vehicle exhausts pollution.