[Variation Characteristics and Source Analysis of Atmospheric Ozone Pollution in Guanzhong Region]

Guanzhong urban agglomeration has a good development foundation and great development potential, and it has a unique strategic position in the national all-round opening up pattern. In recent years, the problem of near-surface ozone （O₃） in the Guanzhong Region has become increasingly prominent, which has become a bottleneck affecting the continuous improvement of air quality. In order to effectively prevent and control O₃ pollution, this study analyzed the characteristics of annual, monthly, and daily changes in O₃ concentration in the Guanzhong Region based on the environmental monitoring data from 2018 to 2021. A geo-detector was used to study the driving factors of the spatial differentiation of O₃ concentration, and the sources of O₃ were analyzed using a backward trajectory model and emission inventory construction. The results showed that the daily and monthly variation in O₃ concentration in the Guanzhong Region were unimodal. The daily maximum value appeared at 15：00, the minimum value appeared at 07：00, the peak value of the monthly average appeared in June, and the valley value appeared in December. The O₃ concentration was highest in summer, followed by that in spring, and the lowest in winter. The days of O₃ exceeding the standard showed mainly mild pollution, and moderate and above pollution showed a trend of decreasing first and then increasing. The O₃ concentration in the Guanzhong Region was mainly closely related to precursors and meteorological factors, and the explanatory power of the interaction of each factor was significantly greater than that of any single factor. The regional transport of O₃ concentration in the Guanzhong Region was mainly affected by easterly airflow, followed by the northwest direction, with the potential source areas located mainly in Henan Province and Hubei Province. The main local sources of volatile organic compounds （VOCs） were solvent use sources, process sources, and mobile sources, and the main emission sources of nitrogen oxides （NO） were mobile sources and industrial production combustion sources. The research results have a guiding significance for O₃ joint prevention and control in the Guanzhong Region.