Potential of some landscape trees as biomonitor of elemental pollution in urban areas, city of Hamedan, Iran

This study was conducted to assess the monitoring and mitigation of metal(loid) pollutants (As, Cd, Cu, Pb, and Zn) by common tree species viz. Robinia pseudoacacia and Pinus eldarica, growing in residential, commercial, and industrial regions of Hamedan, Iran. In carrying out the study, totally, 180 unwashed and washed leave/needle and also soil specimens were collected from 12 sites in June 2023. The obtained results showed that the greatest quantities of all the investigated plant and soil elements were observed in samples collected from the commercial and industrial areas, indicating the influence of anthropogenic activities on element concentrations. The significant positive correlations between As, Cd, Cu, and Pb in tree leaves/needles (washed) and soil of R. pseudoacacia (0.864, 0.784, 0.673, and 0.779, respectively) and P. eldarica (0.908, 0.681, 0.676, and 0.797, respectively) showed their potential use as biomonitors for the mentioned elementals (p < 0.01). The higher comprehensive bio-accumulation index (CBAI) for R. pseudoacacia with 0.476 makes it suitable for phytoremediation of soils contaminated with multiple elements, while the higher metal accumulation index (MAI) in P. eldarica with 19.5 makes it appropriate for controlling the contents of elements in the air of contaminated areas. Based on the air-originated metals (AOM) values, both studied species have a remarkable capability to trap and retain dust particles. The study concludes that R. pseudoacacia and P. eldarica are useful and efficient biomonitors and bioremediators of elements at contaminated environments; therefore, their planting could be highly recommended in urban areas for maintaining environmental health.