Spatiotemporal Variation of Dust Retention in the Leaves of Common Greening Tree Species in Urumqi

To investigate the spatiotemporal variations in particulate matter (PM) retention by common urban greening species, six tree species were studied across different functional zones in Urumqi, China, which includes traffic area (TA), residential area (RA), park area (PA), and landscape ecological forest (LA) at varying altitudes. We measured the retention of PM0.2–3, PM3–10, PM>10, and PMtotal for Pinus sylvestris, Picea asperata, Ulmus pumila, Ligustrum obtusifolium, Ulmus densa, and Fraxinus rhynchophylla. Results showed significant differences (p < 0.05) among functional zones, with retention capacity following the order that evergreen trees > deciduous shrubs > deciduous trees. Specifically, P. sylvestris and Picea asperata exhibited the highest overall PM retention. Temporally, PM accumulation increased over time, reaching a minimum 3 days after heavy rainfall (>20.4 mm) and a maximum after 23 days. Spatially, retention was highest in the TA and lowest in the PA. On Yamalike Mountain, PM3–10 and PM>10 retention by Ulmus pumila increased significantly with altitude, while other fractions showed no clear trend. These findings suggest that the spatiotemporal differences in PM retention are distinct, and the strategic selection and management of species in specific urban environments can significantly enhance the regulation of atmospheric particulate pollution.