Assessment of urban ecological conditions using heavy metal accumulation in the leaves of Paulownia and Acer

Amid intensified urbanization and industrial expansion, heavy metal (HM) contamination has become a critical challenge for urban ecosystems. Toxic elements such as lead (Pb), cadmium (Cd), iron (Fe), copper (Cu), arsenic (As) and chromium (Cr) threaten both public health and environmental stability. This study evaluates the bioaccumulation capacity of two widespread urban tree species-Paulownia and Acer-within different districts of Osh city. Leaf samples were collected across multiple seasons and HM concentrations were quantified using inductively coupled plasma optical emission spectrometry (ICP-OES). The findings demonstrate pronounced spatial and seasonal variability, with the highest metal levels recorded in districts under strong anthropogenic pressure. Paulownia consistently accumulated more Fe and Cu than Acer, particularly during autumn, when atmospheric deposition intensifies. These results highlight the suitability of Paulownia not only as an effective bioindicator but also as a promising species for phytoremediation. These findings demonstrate the strong influence of urban structure, seasonality and species-specific traits on patterns of metal accumulation. Overall, the results highlight the value of Paulownia as a sensitive bioindicator and a promising species for phytoremediation, providing practical insight for urban ecosystem health assessment and evidence-based planning of sustainable green infrastructure in rapidly developing cities.