Study On Characteristics And Reduction Potential Of Vehicle Emission In Chongqing Main City

In recent years,the pollution of motor vehicle exhaust in the main urban area of Chongqing has become more and more serious,and is making more and more contribution to the local atmospheric compound pollution.It has become the key to improve the air quality in the main urban area of Chongqing to study the emission characteristics and temporal and spatial distribution rule of motor vehicle exhaust pollutants,as well as to formulate and evaluate effective control measures for motor vehicle pollution.Hence,in this work,based on the test data of the vehicle detection station,the dynamic traffic flow information data of the traffic intersection and the load length in the main city of Chongqing,the CO,VOCs,NO_x,and PM₁₀ emissions from different types of motor vehicles in the inner rings and outside the inner ring of the main urban area which includes the expressway,main road,and secondary trunk road was calculated by the International Vehicle Emission model.Furthermore,the emission characteristics of vehicle exhaust pollutants in the main city are analyzed.Moreover,through the distribution of pollutants,a spatial distribution list of vehicle exhaust pollutants in the main urban area of Chongqing was established,and the NO_x emission inventory of motor vehicles was verified by the atmospheric diffusion model ADMS-Urban.Based on the essential data in 2017,the emissions of motor vehicle exhaust pollutants in the target year of 2022 were calculated.Combination with the different structural,management and engineering measures in Chongqing in the future,the emission reductions of various measures were calculated.The vehicle pollutant emission reduction scenarios have been designed,which was the existing control scenarios and six intensified control scenarios?the tail number is limited,the old vehicles are eliminated,the strict vehicle emission standards and various combinations of the three measures are used?,respectively.The effect of pollutant emission reduction in different emission reduction scenarios was assessed.The main conclusions are as follows:The emissions of CO?VOCs?NO_x and PM₁₀ from vehicle exhaust in the main urban area of Chongqing in 2017 were 23.0×10⁴,1.3×10⁴,4.2×10⁴and 0.4×10⁴ tons,respectively.The emission of pollutants from small buses,light goods vehicle and heavy goods vehicle accounted for about 86.0%of the total emission of motor vehicles.The share rates of CO,VOCs and NO_x emission from small buses were 54.4%,55.6%and30.4%respectively.The share rates of PM₁₀ and NO_x emission from goods vehicle were59.2%and 31.8%respectively.The share rates of light goods vehicle of CO,VOCs and NO_x and PM₁₀ was 24.91%?24.34%?23.33%and 18.22%respectively.The emission of motor vehicle exhaust pollutants in the main urban area is large in expressways and main roads.The spatial discharge intensity shows a trend of decreasing within the inner ring of the main urban area to the outside of the urban area.However,PM₁₀ and NO_x emissions in the secondary trunk roads outside the inner ring remain high strength.The simulation values of the NO_x emission inventory diffusion results from the ADMS-Urban model and the monitoring values of 27 air quality monitoring stations in the main urban area shows a good correlation,indicating that the calculation results of the emission inventory are close to the actual ones.It is estimated that by 2022,the CO,VOCs,NO_x and PM₁₀ emissions of motor vehicles in the main urban area of Chongqing will be 39.0×10⁴,2.1×10⁴,5.9×10⁴ and0.5×10⁴ tons,respectively.Compared with the data in 2017,the emissions of pollutants increased significantly.Therefore,certain intensive control measures under different emission reduction scenarios must be taken to control pollution within the 2017emissions range.Among them,the strict emission standard of in-use vehicles?Enhanced scenario 3?is regared as the most effective single-item intensified control measures to reduce the emissions of motor vehicles.Excitingly,the average emission reduction ratio for the four pollutants is 28.5%.When the three intensive control measures were carried out simultaneously?Enhanced scenario 7?,the emission reduction ratio of the four types of pollutants was above 34.4%.