Traffic-pollution Research Based On Line Source Model-a Case Study In Taiyuan

In recent years, with rapid growth of motor vehicles amounts, motor vehicle exhaust pollution has become an important source of air pollution in number of major cities of China, and there is also a rapid growth speed of motor vehicles amounts in Taiyuan year by year, as a result of that the city is in the turning of coal-burning pollution to the mixed type. Street canyon pollutants diffusion is a complex process, was determined by a number of factors, including emission speed, meteorological factors and terrain conditions.In this paper, the author collected vehicle amounts, the vehicle types, engine condition, etc. calculated average emission factor based on Mobile6 mode and accord to streets terrain conditions and meteorological characteristics, the spatio-temporal distribution was calculated based on OSPM model and CALINE4 model. At the same time, the typical city roads were selected for monitoring of different seasons and different times of the day to compare the two modes of calculating the result and the difference between the measured values for parameter adjustments. The results were showed in the GIS platform, and the results show that:1) It is can be indicated that:the motor vehicle emission was on a higher contribution rate and become a main resource of air pollution; the minitype vehicles amount was larger, frequency and high passenger load, due to this, minitype vehicles is a major contributor of motor vehicle pollution; bus is another major source of pollution of the exhaust; compare to minitype vehicles and bus, the large and medium-sized passenger car exhaust pollution was small share to some extent.2)The spato-temporal distribution show that:the pollutants concentration was higher in the winter than in summer; the highest pollution concentration was found in the morning, the pollutant concentration is higher in fast-track road than the general road.3) Wind speed and street high-width showed a significant impact with pollutants concentration. The proliferation of wind direction on the impact of pollutants in the main street through the change in the flow field is achieved; as well as buildings on both sides of the neat streets of the city streets within the extent of the spread of pollution will have an appreciable effect, but not significantly.4) The proliferation of motor vehicles on the city model studies have shown that the adjusted amended, OSPM, CALINE4, a crossroads for Taiyuan generated model of the input file can be on the street after the vehicle emission pollution dispersion simulation for better. The main changes applied to Taiyuan OSPM parameter is the speed of the experience of conversion factors and constant wind-tunnel test.5) Vehicle pollution control policy was advanced.