Study On Ozone Generation Sensitivity And Source Apportionment In Zhengzhou City In Summer

In recent years,with the accelerated urbanization and industrialization in China,the problem of ozone pollution in summer has become more and more prominent.However,the research on ozone pollution was mostly concentrated in the more economically developed regions,and the research on ozone pollution in central regions is relatively weak.In this paper,we used the WRF-CMAQ model coupled with the DDM method to simulate the sensitivity of ozone generation in Zhengzhou City,a representative city in the central region,for ozone pollution research.The pollutant source analysis function developed based on the CMAQ air quality model was used to analyze the ozone sources in Zhengzhou City in June and to explore the contribution of three regions and nine types of local pollutant emission sources to ozone generation in Zhengzhou City,with a view to providing scientific reference for the development of ozone pollution control measures in Zhengzhou City.First,through the analysis of the 2019 ozone observation data in Zhengzhou City,it was determined that June 2019 was the most severe month for ozone pollution in Zhengzhou City and was most suitable for studying ozone pollution.Further analysis of the relationship between ozone and meteorological factors in Zhengzhou City using meteorological observation data and ozone observation data showed that ozone concentration in Zhengzhou City was positively correlated with temperature,negatively correlated with relative humidity overall,and weakly positively correlated with wind speed.Secondly,based on this emission inventory,meteorological monitoring data and air quality observation data,the accuracy of meteorological model WRF and air quality model CMAQ were evaluated,respectively.The results show that the WRF-CMAQ model system can simulate the characteristics of ozone concentration changes in Zhengzhou city and can be used in the follow-up study of ozone pollution in Zhengzhou city.Then,an ozone sensitivity study was conducted based on the CMAQ-DDM model.The results show that most of the areas in Zhengzhou city,except Dengfeng city,belonged to VOCs sensitive areas,and Zhengzhou city should focus on VOCs in O₃ pollution control to develop control measures.Based on the O₃ sensitivity characteristics,the reduction effects of O₃ precursors in Zhengzhou city were analyzed under different control pathways.The results show that the emission reduction dVOC/dNOx of ozone precursors must be greater than 2:1 to achieve a sustained reduction of O₃ concentration.Finally,the ozone source analysis study was conducted based on the SourceOriented CMAQ model.The results show that the largest contribution to the ozone concentration in Zhengzhou was the background value,with a contribution of 43.59%;the contribution of local source emissions in Zhengzhou was 32.86%;the contribution in Henan Province was 19.21%;and the contribution from outside Henan Province was 4.34%.Therefore,the main focus of prevention and control of O₃ pollution in Zhengzhou is still the reduction of pollutants from local emission sources and the joint prevention and control in the provincial regions.Among the local emission sources,mobile sources contributed the most to ozone generation in Zhengzhou,followed by industrial sources and power plant sources.By analyzing the differences in the contribution of each source to ozone generation on polluted days and non-polluted days,it was clear that different measures should be taken to control ozone pollution in suburban and urban areas of Zhengzhou.