Identification Of Indicative VOCs In Atmosphere And Soil Based On Automobile Exhaust Emission

The number of urban motor vehicles in China is growing at about 13% every year,according to statistics,as of 2016,the number of motor vehicles in China has reached more than 279 million vehicles,which contains 172 million gasoline vehicles.Motor vehicle exhaust pollution,has become the main source of air pollution.Automobile exhaust contains a variety of VOCs,many known VOCs have toxicity neurotoxicity,and the toxicity to the kidney and liver is larger.Some VOCs are teratogenic,carcinogenic,mutagenic,can damage blood components,and have strong carcinogenic and carcinogenic properties to the cardiovascular system.The atmosphere and soil are often used as the direct pollution areas and migration transformation areas of volatile organic compounds.The research about relationship between automobile exhaust and VOCs of soil and atmosphere is the important basic research for the analysis of the source of VOCs.It is also an important subject for the environmental engineering field.It provides an important basis for the establishment of monitoring indexes of organic pollutants.It plays an important role in human health and sustainable development,the control of pollution sources and environmental governance,and the management of ecological environment.This paper focuses on the impact and contribution of the main VOCs in the exhaust gas on the environment,and reflects the impact of exhaust gas on the environment by means of indicative VOCs of exhaust emissions,and provides an important method for source apportionment.In this study,the best methods were established to detect the VOCs in soil,air and exhaust,through the analysis of the differences between them,the indicative components of automobile exhaust pollutants in air and soil environment are determined,the main research contents are as follows:Firstly,establishment of emission spectrum of automobile exhaust(1)Detection methods of the 34 kinds of volatile compounds in the environment by thermal desorption cold trap analysis / GC-MS were established.This method has a good separation effect and a good linearity in a certain concentration range,the linear correlation coefficients are between 0.9480 ~ 0.9993,the relative standard deviation(RSD)ranged from 2.5% to 6.4%,the detection limits are 0.005 ng/L ~ 0500ng/L.The method has the advantages of simple operation,rapid analysis,highaccuracy and high sensitivity,34 kinds of volatile components in gas were determined by thermal desorption / cold trap analysis / GC-MS.The qualitative and quantitative results were satisfactory.(2)The two VOCs components spectrums which are direct sampling and source dominant sampling of vehicle exhaust were obtained.There are differences in the composition of automobile exhaust gas with different sampling methods.The six main components of automobile exhaust gas are determined by comparative analysis,they are toluene,ethylbenzene,p-xylene,methyl 1,2,4-,three benzene,o-xylene,1,3,5-three methyl benzene,all of them are stable in all kinds of automobile exhaust and road air.Secondly,the study on the indicative VOCs in air from automobile exhaust:(1)The possible pollution sources(Automobile exhaust emission,housing decoration,kitchen smoke,biomass)in the environment were detected and investigated at the same time.According to the research results of automobile exhaust gas composition spectrum,the contribution of six components from housing decoration,kitchen smoke,and biomass is minimal,this proves that the six components of the environment are derived from the vehicle exhaust.(2)In 2016,seventy-one samples were sampled in Lanzhou area,and the source of VOCs in the atmosphere was analyzed by principal component analysis.Compared with the results of automobile exhaust detection,the results showed that the source of the six components was automobile exhaust.The simulation results are consistent with the results of the experimental analysis.It shows that it is feasible to use the characteristic components of VOCs in automobile exhaust gas to analyze the VOCs source in the environment.Thirdly,the relationship study between VOCs in soil and automobile exhaust:(1)Three kinds of analytical methods were established.Three kinds of sampling methods and pretreatment methods were analyzed and compared.The methodological validation was conducted and the method parameters were compared.One of the best pretreatment method was chosen to detect VOCs in the soil.(2)The components of automobile exhaust and soil were determined by thermal desorption/GC-MS.The ten main components of automobile exhaust weredetermined as follows: toluene,ethylbenzene,m-xylene,p-xylene,1,2,4-three methyl benzene,o-xylene,1,3,5-two methyl benzene,toluene,ethyl benzene 4-and dichloromethane,all of them are stable in all kinds of automobile exhaust.(3)The ten components in the soil were tested,and the component contents in soils of different distance from the road were analyzed.The differences and the relationship between them were studied.Finally,the eight components in the soil were mainly caused by automobile exhaust.