Study on Transmission Channel and Pollution Sources Region of O₃ in Qingyuan City

Based on the Lagrange mixed single-particle trajectory model and NCEP global reanalysis meteorological data, the 72 h backward airflow trajectory in Qingyuan City in different seasons from 2018 to 2020 was analyzed by cluster analysis. Combined with the hourly average concentration data of O₃, the potential source contribution factor (PSCF) analysis and concentration weighted trajectory (CWT) analysis were used to study the regional transport and possible source area of O₃ in Qingyuan City and analyzed the relationship among O₃ and wind speed, wind direction, NO₂, and CO. The results showed that from 2018 to 2020, the most significant proportion of primary pollutants in Qingyuan City was ozone. The annual average concentration reached the highest value since monitoring in 2019. In 2020, the impact of epidemic prevention and control decreased. The daily average concentration change characteristics showed a single peak, with the highest concentration in the afternoon, the highest peak concentration in summer, followed by spring, and the lowest concentration in winter. There are differences in the concentration of O₃ between different sources of airflow in Qingyuan City. The potential source contribution factor shows that the high-value covered areas are mainly in Guangzhou, Foshan, and Zhongshan, which can be considered the main potential source areas. These areas can be regarded as the main potential source areas. The concentration weight trajectory showed that external and local sources affected the O₃ pollution in Qingyuan during the four seasons. The high ozone concentration in Qingyuan mainly appeared in the south wind direction, indicating that the high ozone concentration in Qingyuan was greatly affected by the external transmission of the southern Pearl River Delta. The correlation between ozone concentration and CO concentration is poor, and the effect on ozone concentration is less than that of NO₂.