Long-term monitoring reveals air pollution and its relationship to deposition in karstic suburb of one typical industrialized city, SW China.

Rapid urbanization and industrialization can induce air pollution and its regional diffusion from cities to suburbs. This effect might be more complicated in karst regions accompanying peak clusters but remains unclear. In this study, high-frequency monitoring of air quality, rainfall, and dustfall was synchronously conducted for 7 consecutive years in the karst suburb of one typical industrial city, to explore air quality variation at diverse time scales, impacts of regional deposition, primary sources of air pollution, and dominant controls. Air quality in the coming decades was also predicted. The results showed periodic fluctuations on a daily scale for concentrations of all atmospheric parameters (PM, PM, SO, NO, CO, and O) but downtrends on an annual scale, except the uptrend for O. Specifically, O levels were higher in summer than in winter, contrary to the seasonal trend of other parameters. This difference in temporal trends is mainly due to the influence of combustion of fossil fuels and emissions from automobile exhaust on other parameters, especially in this karstic suburb where the widespread peak-cluster depression landforms limit their diffusion and interregional transport. The policy implementations can regulate artificial activities well and weaken the potential negative effects of the resultant emissions on air quality. The natural barriers formed by peak clusters in this karstic suburb reduce the diffused impact of industrialized city and only 9 pollution events were found here during 2017-2023. The potential pollution source areas were mainly composed of Guiyang, Chengdu and Nanning according to backward trajectory analysis and Potential Source Contribution Function (PSCF). Only O is predicted to increase slightly in the future and deserves more attention when developing atmospheric control strategies. This study highlights the role of karst landforms and the importance of regional cleaner production in this karstic suburb. SIGNIFICANCE STATEMENT: In karst regions, the widespread peak-cluster depression landforms act as natural barriers to atmospheric pollutants' diffusion and their interregional transport. This study aims to investigate the atmospheric environment and its major controls in the karst-dominated suburb of one typical industrialized central city. This is important for developing local atmospheric control strategies in karst regions. Our results highlight the importance of local emissions over the industrial city's radiation in the karst-dominated suburbs, and local cleaner production should be the primary consideration in protecting the atmospheric environment.