2015—2021年四川盆地近地面O3时空演化及潜在源区分析

近地面O₃污染已经成为我国最严重的环境问题之一，特别是在地形相对闭塞的盆地区域更加突出，而盆地地形区域O₃的时空演化、潜在源区及驱动因素尚未被完全揭示.因此，以典型盆地地形区—四川盆地为研究区，基于长时间尺度(2015—2021年)的O₃浓度监测数据，采用后向轨迹、时空地理加权回归等模型探讨O₃的时空变化特征、传输路径、潜在源区以及驱动因素的空间分布特征.结果表明：(1)时间分布上，2015—2021年四川盆地O₃-8 h浓度第90百分位数为(143±7)μg/m³，夏季O₃-8 h浓度高于其他季节，O₃-8 h浓度存在明显的“周末效应”和昼夜差异.(2)空间格局上，四川盆地O₃-8 h浓度第90百分位数总体呈西高东低的分布特征，西部平原地带是核心污染区域.(3)2015—2021年影响成都市的气流轨迹中短距离输送轨迹占比为74.24%，长距离输送轨迹占比平均值为25.76%. 2015—2...

Spatiotemporal Evolution and Potential Source Areas of Surface Ozone in the Sichuan Basin during 2015-2021

Surface ozone pollution has become one of the most prominent environmental problems in China, especially in the topographically isolated basin areas. However, the spatial and temporal evolution, potential source areas and driving factors of O₃ in the basin topographic region have not been systematically studied and confirmed. In this study, the Sichuan Basin was chosen as a typical case site, and real-time O₃ monitoring data of long-term monitoring stations were selected for analysis. The backward trajectory, geographically and temporally weighted regression were used to explore the spatiotemporal variation characteristics, transport paths, potential source areas and distribution characteristics of driving factors of O₃. (1) The results showed that the average 90th percentile of the O₃-8 h concentration in the Sichuan Basin was (143±7)μg/m3 from 2015 to 2021. The O₃-8 h concentration in summer was higher than that in other seasons, and O₃ pollution in May should be focused on. In addition, there were significant ‘weekend effects’ and diurnal differences in O₃-8 h concentration. (2) Spatially, the average 90th percentile of the O₃-8 h concentration in the western regions of the Sichuan Basin was higher than that in the eastern regions, and the western plain was the core area of O₃ pollution. (3) From 2015 to 2021, the influence of short-range air mass trajectories on airflow transport in Chengdu City was dominant (74.24%). The potential source areas of O₃ pollution in Chengdu migrated from west to east, showing a trend of gradual accumulation in the basin. (4) The geographically and temporally weighted regression results showed that the regression coefficients of temperature and sunshine duration were 0.738 and 0.289, respectively, which were the dominant natural factors of O₃ in the Sichuan Basin. Population density (0.412) and per capita GDP (0.369) were the main socio-economic factors influencing O₃ concentration. The study showed that O₃ pollution in the Sichuan Basin was relatively serious from 2015 to 2021 due to the combined influence of natural environment and human activities.