Research On The Influnce Of The PAHs In Antomobile Tail Gas To Air Enviorment In Xi'an City

As the number of automobile increase rapidly in xi'an city, the exhaust pollutants from automobile have been a serious environmental issue that cannot be ignored,The number of automobiles of Xi'an was more than 330000 at the year of 2005, and this number will attain 500000 till 2010, The exhaust pollutant has become the main root of the city's air pollution. The research indicate that automobile exhaust discharges particulate often stick polycyclic aromatic hydrocarbons(PAHs) some of them are known as carcinogens, but little literatures were reported on this issue. The present thesis has carry out some of the researches on the PAHs containing in exhausts of the automobiles.Base on the numbers of automobile in Xi'an city and the situation of vehicle circulates, 3 kinds of typical automobile have been choosen as study objects: with carburettor engine, with electronic fuel injection(EFI) engine and with Compressed Natural Gas power (CNG) engine, collected 2 kinds of enging working situation's sample as idle and 30km/h. as the way how to collect samples and extract it have been probed, the samples was extracted in the method of Soxhlet. Measured the Polycyclic aromatic hydrocarbons in these samples in GC-MS method. Analyzed the situation of the polycyclic aromatic hydrocarbons of vehicle exhaust. Compared with the air sample collectd in street crossing, and accoding to the numbers of Xi'an 's automobile of 2005/2010 year, total contents of the PAHs by vehicle exhuast in these two years has been computed and predicted.The results were as follows on the basis of the experimental datas: PAHs in vehicle of CNG are mainly Naphthalene and Fluoranthene, 4 other kinds of Pahs :Phenanthrene, Pyrene, Indeno [l,2,3-cd]pyrene and Benzo[ghi]perylene is found in samples of the vehicles of EFI and CNG , 8 kinds of Pahs is found in sample of road crossing: Naphthalene , Acenaphthylene, Acenaphthene, Flourene, Anthrancene,Phenanthrene, Fluoranthene and Pyrene. In all of the samples, Naphthalene and Fluoranthene are the main pollutants. And the content of PAHs in all samples have been measured.by comparing general amount of PAHs in exhaust polltants of three kinds vehicles, the order is: carburetor > EFI >CNG, and the working situations' order is: idle situation> 30KM/h situation. Accoding to the numbers of Xi'an 's automobile of 2005 year, total contents of the PAHs by vehicle exhuast in the year is 242.6 ton, and Accoding to the numbers of Xi'an 's automobile of 2010 year(predict datas), total contents of the PAHs by vehicle exhuast in the year will be 353.4 ton.According to the traffic conditions and street circumstances present in Xi'an, paper finally discuss the characteristic of effects of the PAHs in exhaust pollutants discharged from automobiles in xi'an city on the atomsphere, and some measures to control the pollutants of the exhaust from the automobiles were given.