[Spatiotemporal Distribution and Potential Source Areas of PM_2.5 Pollution in Xianyang City, Guanzhong Basin]

This study employed PM_2.5 concentration data for Xianyang City spanning the years 2014 to 2021, in conjunction with the global data assimilation system （GDAS）. Various analytical techniques, including backward trajectory clustering analysis, potential source contribution function （PSCF）, concentration weighted trajectory analysis （CWT）, and relevant statistical methods, were employed to investigate the temporal and spatial variations in PM_2.5 pollution. Furthermore, this research aimed to elucidate the source characteristics and potential areas contributing to PM_2.5 pollution within Xianyang City. The results revealed a fluctuation in PM_2.5 pollution concentration in Xianyang City from 2014 to 2021, with an initial increase followed by a subsequent decrease. The peak average annual concentration, reaching 81.25 μg·m^-3, was recorded in 2016. Seasonal variations indicated higher PM_2.5 concentrations in autumn and winter, contrasting with lower levels in spring and summer. Winter exhibited the highest PM_2.5 concentration at 116 μg·m^-3, while the lowest was recorded in summer at 31.58 μg·m^-3. Spatially, the annual mean distribution of PM_2.5 in Xianyang City demonstrated heightened pollution in the southern and central regions, juxtaposed with lower pollution in the northern areas. Cluster analysis highlighted that Xianyang City experienced substantial influence from northwest airflow during spring, autumn, and winter, while short-distance transport dominated during the summer months. PSCF and CWT analyses indicated that the high-value potential source contribution areas were most extensive during winter, followed by spring and autumn. Conversely, the high-value area in summer was the smallest. The potential source areas were concentrated within Xianyang City and extended northwest to southeast, encompassing regions in western Inner Mongolia, central and eastern Gansu Province, central and southern Ningxia, and central Henan. In analyzing periods of heavy pollution, the study demonstrated that PM_2.5 pollution in Xianyang City was primarily induced by westerly airflow. High PM_2.5 concentrations were influenced by the surrounding areas of Xianyang City and the source zone, akin to regions with high potential source values during the winter. As a consequence, mitigating PM_2.5 pollution in Xianyang City necessitates stringent control measures for both local and regional pollution sources. Additionally, regional collaborative efforts should be emphasized to prevent external pollution sources from exacerbating persistent pollution episodes in the region.