Abstract:

The impact of surface O₃ on air quality in China has intensified, making it the primary pollutant for air quality management. As a gateway to Northwest China, Xinjiang has undergone rapid economic development, resulting in air quality issues, particularly in Urumqi and Kashgar. In this study, we analyzed the variation characteristics and potential sources of O₃ in these cities and employed a backward trajectory model to explore transmission paths, potential source areas, and influencing factors. The results indicated the following: (1) From 2015 to 2022, O₃ concentrations in Urumqi and Kashgar peaked in 2018, followed by a slight decrease and subsequent stabilization. O₃ concentrations showed significant seasonal variations, with the highest concentrations occurring in summer, alongside weekend effects and diurnal fluctuations. (2) Backward trajectory analysis revealed that from 2015 to 2022, airflow sources in Urumqi and Kashgar were similar, with long-distance airflows primarily originating from the western Central Asian region. Long-distance transport trajectories account for 31.86% of airflow trajectories in Urumqi, compared to 15.42% in Kashgar. Conversely, medium- and short-distance airflows mainly come from local sources, constituting 68.14% of the trajectories in Urumqi and 84.58% in Kashgar. (3) Urumqi and Kashgar encompass extensive potential source areas. In Urumqi, local sources are the primary contributors, while potential sources in Kashgar include both local and external origins. The range of high-value potential source areas expanded in 2022 compared to 2015.

Key words: Urumqi, Kashgar, near ground O₃, backward trajectory, potential source area