Research On The Pollution Of O₃ And PM_2.5 During The "14th Five-Year Plan" Period In Yulin City Based On The CMAQ Model

During the"Thirteenth Five-Year Plan"period,my country’s air pollution prevention and control battle has achieved significant results,but the regional air pollution problem dominated by fine particulate matter and ozone is still prominent.In accordance with Yulin’s"14th Five-Year Plan"industrial development plan and air pollutant control plan,this study studied changes in air pollutant emissions during the"14th Five-Year Plan"period and regional ozone and fine particulate matter at the end of the"14th Five-Year Plan"period（2025）.Changes in pollution status.Firstly,based on the MEIC inventory,the point source emission data of the industrial parks planned and constructed during the"14th Five-Year Plan"period in Yulin,and the emission changes of regional pollution sources during the"14th Five-Year Plan"period,the SMOKEv4.7model was used to couple the regional natural source emission inventory to establish a The base case（2019）air pollutant emission inventory of the study area and the air pollutant emission inventory at the end of the 14th Five-Year Plan（2025）;secondly,a two-layer nested WRF-CMAQ air quality model suitable for the study area was built.The model was used to simulate the pollution of fine particulate matter and ozone in four representative months（January,April,July,and October）in the study area in 2019 and 2025,respectively.The simulation results were compared and analyzed with the actual monitoring values to verify the simulation effect of the meteorological model WRF4.0 and the air quality model CMAQ5.3;based on the verified WRF-CMAQ air quality model,the pollution characteristics of the two pollutants were studied.spatiotemporal distribution characteristics.Finally,the CMAQ-ISAM module was used to analyze the contribution of four types of anthropogenic sources to ozone and fine particulate matter in the study area at the end of the"14th Five-Year Plan"period（2025）.The main conclusions of this study are as follows:（1）The comparison of the two sets of air pollutant emission source inventories shows that by the end of the“14th Five-Year Plan”period,the total annual emissions of NOX and SO2 in the study area increased by 9.17%and 4.17%respectively,and the annual emissions of PM_2.5,PM10and VOCs increased by 9.17%and 4.17%respectively.Total emissions were reduced by-19.16%,-17.10%and-9.20%,respectively.（2）The model evaluation results show that the weather model WRF4.0 simulation of meteorological elements and the air quality model CMAQ5.3 simulation results of ozone and fine particles have a high correlation,indicating that the WRF-CMAQ air quality model built The simulation results can better reflect the characteristics of fine particulate matter and ozone pollution in the study area.（3）The CMAQ simulation results show that the monthly average ozone concentration in2025 and 2019 varies significantly from month to month,with the highest in July and the lowest in January;from the perspective of spatial distribution,the monthly average concentration of ozone in the study area.The urban area and industrial park are low-value areas,and the concentration values gradually increase around the low-value areas;compared with 2019,the monthly average ozone concentration in the four national control points is not significantly increased in January,April,July,and October（maximum increase of 0.91%）,the regional average concentration of the four-month increase was not obvious（maximum increase of 0.68%）,the average change in ozone area was small,but the concentration changes in the surrounding areas around the urban area were more significant,and the maximum change was located in Shenmu.Around the urban area,the four-month change rate is the largest at 2.36%;for the four national control points,the long-distance transportation of ozone concentration outside the area is obvious,and the transportation outside the area contributes the most to July with the highest monthly average concentration,accounting for 86.04%,from the concentration contribution of local anthropogenic sources to the state-controlled sites,the main source of contribution is the power source.（4）From the monthly variation of fine particulate matter concentration,the monthly average concentration of fine particulate matter in 2025 and 2019 varies significantly,with the highest in January and the lowest in July;from the perspective of spatial distribution,the monthly average concentration of fine particulate matter in the study area in 2025 is in Shenmu.The main urban area of the city,Yushen Industrial Park and the main urban area of Yuyang District reached the regional maximum,of which the maximum regional concentration in January was 146.52μg/m3;compared with 2019,the monthly average concentration of regional fine particles dropped significantly,and the maximum concentration in four months The monthly change rate was-12.90%,the change rate of the four state-controlled sites was higher than the regional average,and the maximum change rate of the four-month monthly average concentration of the state-controlled sites was-14.95%in July,and the fine particle pollution improved significantly during the"14th Five-Year Plan"period;The concentration of fine particulate matter is mainly affected by local pollution sources,and the contribution of local pollution sources in the four months is the largest at 85.39%in October;from the concentration contribution of local anthropogenic sources to state-controlled sites,the main sources of contribution are civil sources and industrial sources.