Study On Vehicle Emission Pollution And Control Strategies In Xi'an

An increasing possession quantity of motor vehicles is being achieved rapidly in Xi'an with average annual rate of 15.39%, and the volume of motor vehicles had reached 1.22 million by the end of the year 2010. According to monitoring results of environmental protection department, HC, CO and NOx concentrations of roads in downtown area have been increasing year by year, which have exceeded national ambient secondary standard 1.03 to 4.16 times. Air pollution in Xi'an has been changed from coal burning caused pollution to coal burning-vehicle composite pollution as motor vehicle emissions beginning to be one of major emission sources in city. Through the quantification of emissions from motor vehicle, scientific bases for decision making can be provided to predict the environmental impact of vehicle emissions on atmosphere and to develop and carry out vehicle emission pollution control strategies.MOBILE model, which is widely used at home and abroad in vehicle emission research, is adopted to calculate vehicle emission factors of Xi'an in this dissertation. Based on emission factors, vehicle emission inventory of Xi'an is established, and the total amount of vehicle emission in 2010 is also calculated, as well as emission contribution rate of each vehicle type and emission intensity of typical traffic artery. Several suggestions are given in order to reduce vehicle exhaust pollutants. The main conclusions are as follows:Through the calculation of vehicle exhaust pollutants in Xi'an, total vehicle emission quantities are 590,310 tons, including 64,250 tons of HC,445,870 tons of CO and 80,190 tons of NOx.HC, CO and NOx emissions of Light-Duty Gasoline Vehicles account for 62.99%, 67.18% and 20.08% of total emission quantities, respectively. Motorcycles have also exhausted a substantial amount of HC and CO. Heavy-duty diesel vehicles contribute 55.31% of NOx emission quantities, which is obviously higher than other vehicle types.Being one of the expressways in city, the 2nd Ring Road's emission intensity of the three pollutants are 1.9 times,2.63 times and 1.39 times higher than other arteries, respectively. Emission intensity of arterial road in urban centers is much higher than that in suburbs, which is quite similar to traffic distribution. The three pollutants's emission intensity of arteries within the 1st Ring Road is 1.32 times,1.23 times and 1.52 times higher than that in other areas. Traffic volume is the most important factor affecting emission intensity of urban arteries in same grade.Finally, two main suggestions based on specific situation of Xi'an are proposed to reduce vehicle emission pollution, including the optimizing of traffic and methods of reducing single vehicle emission.