Research On Air Pollution Characteristics And PM_2.5 Pollution Transport Of Major Cities In Jilin Province During The "13th Five-Year Plan" Period

With the continuous acceleration of industrialization in China,the regional air pollution problem represented by particulate matter pollution has become increasingly prominent.In order to alleviate the air pollution problem,the Chinese government has promulgated a series of air pollution control policies,but fine particles(PM_2.5)is still the primary pollutant in many urban areas,and the ambient air pollution is still very severe.Particulate matter pollution is affected by both local pollution emissions and regional transport.Jilin Province is located in the central part of northeast China and is one of the important old industrial bases,as well as a vital window for foreign trade in China.In order to further improve the regional air quality in Jilin Province,it is especially necessary to explore the problem of air pollution transport between cities in Jilin Province.Taking Jilin Province as the research object,this study constructs a double-layer nested WRF-ISAT-CMAQ model suitable for Jilin Province,and uses ISAT inventory processing tools and Arc GIS software to refine the MEIC inventory to provide the Jilin Province required by the model.The localized emission inventory of pollution sources simulates the PM_2.5 concentrations of nine major cities in Jilin Province in January and July of 2015 and 2019.This study uses the CMAQ-ISAM source analysis module to estimate the contributions of different kinds of industries and different regions among cities in Jilin Province.In addition,this study uses the centroid analysis method to calculate the centroid coordinates of PM_2.5 pollution in Jilin Province,and also uses trajectory clustering,PSCF,and CWT methods to analyze and study the regional transport characteristics of PM_2.5.The main conclusions are as follows:（1）This study uses the centroid analysis method to calculate the centroid coordinates of PM_2.5 pollution in Jilin Province located at 43.58°N and 125.69°E.Taking this point as the target point,cluster analysis,PSCF,and CWT methods are used to explore PM_2.5 regional transport characteristics.Therefore,the potential source areas of fine particulate matter in Jilin Province in January are western Jilin Province,northern Liaoning Province,and eastern Inner Mongolia;the potential source areas of fine particulate matter in July are southern Jilin Province,Liaoning Province,and other regions.（2）The verification results of the WRF-CMAQ model show that in the four simulated months,the correlation coefficient of temperature ranges from 0.77-0.93,and that of the air pressure ranges from 0.94-0.99.The WRF model can simulate the changing patterns of meteorological elements well.For the simulation of PM_2.5,the correlation performance in January in 2015 and 2019 is better than that in July.The simulation results of all cities have passed the test of statistical indicators,and the change characteristics of PM_2.5 are simulated well.（3）The regional source apportionment results of PM_2.5 show that there is a certain regional transport of PM_2.5 between cities in the central part of Jilin Province,and the transport intensity in winter is significantly greater than that in summer.Compared with the base year（2015）,the local contribution rate of the 9 cities in Jilin Province in 2019all decreased,and the number of cities with long-distance transport as the largest source of PM_2.5 in winter（January）and summer（July）both increased,and the contribution of long-distance transport showed an increasing trend.（4）The results of the sectoral source analysis of PM_2.5 show that the main contributing sources of PM_2.5 in winter in nine cities in Jilin Province are civil and industrial sources.The main contributing source of PM_2.5 in summer in Baicheng City is the electric power source,while the industrial source is the largest contributing source of PM_2.5 in summer in the remaining eight cities except for Baicheng City.The high value concentration areas contributed by each sector are more concentrated near the built-up areas of each city.Compared to 2015,the PM_2.5 concentration levels and the extent of pollution were significantly reduced in 2019.