High Spatiotemporal Resolution Vehicular Emission Inventory In Beijing-Tianjin-Hebei And Its Surrounding Areas (BTHSA) Based On Road Network And Its Scenario Analysis

With the acceleration of urbanization and the continuous improvement of the economic development level,the vehicle population in Beijing-Tianjin-Hebei and its surrounding areas（BTHSA）has also increased rapidly,and vehicle emissions have become the main source of anthropogenic emissions of air pollutants.One comprehensive emission inventory of CO,HC,NO_X,PM_10,PM_2.5,BC,CH₄,CO₂ and N₂O with high spatial resolution（0.01°×0.01°）for 58 cities in BTHSA during 2000-2020 are developed by using COPERT model and Arc GIS methodology.In this study,scenario analysis is used to explore the emission reduction rates of atmospheric conventional pollutants and climate forcers under different scenarios from 2021 to 2030,and finally determine the characteristics of vehicle emissions under the integrated scenario.The research results are significant for the reduction of vehicular conventional pollutants and climate forcers and the improvement of regional air quality.The main findings of this study are as follows:（1）The results show that vehicular emissions of CO,HC,NO_X,PM₁₀,PM_2.5,BC and CH₄ have begun to decrease or slow their growth rates in recent years due to the implementation of measures to control vehicular emissions.However,vehicular emissions of CO₂ increase rapidly due to little fuel economy improvement.Besides,the usage of selective catalytic reduction（SCR）systems by heavy duty truck（HDT）is the main factor impacting the growth trend of vehicular N₂O emissions since 2017.By 2020,vehicular emissions of CO,HC,NO_X,PM₁₀,PM_2.5,BC,CO₂,CH₄ and N₂O are estimated at about 1.65 Mt,0.35 Mt,1.39 Mt,87.44 kt,55.06 kt,15.57 kt,527.71 Mt,36.20 kt and8.56 kt,respectively.Therein,China Ⅲ,Ⅳ,Ⅳ and Ⅳ passenger cars（PCs）are the predominated models for vehicular emissions of CO,HC,CH₄ and CO₂,accounting for19.59-28.26%of the total vehicular emission of corresponding pollutants.Nevertheless,the major contributors of vehicular emissions of NO_X,PM₁₀,PM_2.5,BC and N₂O are China Ⅲ（29.64%）,Ⅲ（18.03%）,Ⅲ（22.81%）,Ⅲ（42.16%）and Ⅴ（22.28%）HDTs,respectively.The gridded vehicular emissions vary significantly,with emissions of CO,HC,CH₄ and CO₂ being mainly concentrated in central urban areas of cities while NO_X,PM₁₀,PM_2.5,BC and N₂O are mainly distributed along the expressway and the suburban roads of cities.Finally,multi-year uncertainties of vehicular emission inventory are discussed.（2）The average annual growth rates of vehicular CO,HC,NO_X,PM_2.5,and PM₁₀emissions under the“business-as-usual（BAU）scenario”for 2020-2030 are about 8.39%,11.51%,2.85%,6.08%,and 4.75%,respectively.The average annual growth rates of vehicular BC,CH₄,CO₂,and N₂O emissions are about 3.23%,4.52%,6.17%,and 9.95%,respectively.For vehicular CO,HC,CH₄,and CO₂,the highest reduction rates in 2030（14.99-21.39%）are achieved under the“new energy vehicles promotion（NEP）scenario”,for vehicular NO_X,BC,and N₂O,“raise emission standards（RES）scenario”and“freight transportation structure optimization（FTO）scenario”are the highest reduction rates in2030（10.33-63.63%）;the NEP scenario and the RES scenario is the highest reduction rate of PM₁₀ and PM_2.5 emissions in 2030（8.80-10.70%）.Under“the integrated scenario”（IS）,the emissions of CO,HC,NO_X,PM₁₀,PM_2.5,BC,CH₄,CO₂ and N₂O from vehicles in 2030 are about 2.11 Mt,0.69 Mt,0.51 Mt,514.50 kt,101.30 kt,54.00 kt,9.80 kt,29.50kt,607 Mt and 14.70 kt,respectively.Compared with the BAU scenario,the emission reduction rates are about 52.29%,51.87%,74.97%,35.79%,38.41%,54.21%,42.80%,36.87%and 33.69%,respectively.Under the IS,by 2030,PCs with National Ⅵ-b emission standards are the major contributors to CO,HC,PM₁₀,PM_2.5,BC,CH₄ and CO₂emissions（28.19-61.47%）;the major contributors of vehicular NOX and N₂O emissions are HDTs with National Ⅵ-b（20.06%and 49.73%,respectively）（3）The results of vehicular emission inventory and scenario analysis in BTHSA are synthesized,and specific countermeasures and suggestions for vehicular emission control in BTHSA are proposed by combining the results of literature research and policy research.Promote new energy vehicles and accelerate corresponding technology development,increase subsidies for scrapping high-emission vehicles,increase penalties for emission violations,further improve vehicle networking and monitoring technology,break through the bottleneck of vehicular non-tailpipe technology development,accelerate the development and implementation of CO₂ emission standards and further improve fuel economy,increase research,development and investment in vehicular tailpipe N₂O emission control technology,increase public transportation funding and optimize the structure of freight transportation are all effective measures to control vehicular emissions.