Abstract Traffic-related environmental pollution is increasing in developing countries due to deficient pollution prevention methods and a lack of use of sophisticated technology. Increasing urbanization, vehicle use, and inadequate environmental regulations cause health and environmental problems. This study assessed the suitability of Robinia pseudoacacia var. umbraculifera DC. as a biomonitor of urban metal contamination in Istanbul by quantifying Al, Ca, Cd, Cr, Cu, Fe, K, Mg, Mn, Na, Ni, Pb, and Zn in washed and unwashed leaves, branches, and bark, together with paired soils collected from ten localities representing contrasting traffic and background conditions. Spatial patterns across independent matrices revealed a clear contaminated-to-background gradient. The control locality (Buyukada) showed the lowest elemental burdens overall, whereas traffic-impacted districts, particularly Besiktas and Bakirkoy, exhibited the highest loads for several traffic-associated elements in plant tissues and co-located soils. Pronounced washed versus unwashed leaf contrasts, strongest at the most impacted sites, indicated a substantial contribution from surface-deposited particulates, consistent with non-exhaust traffic sources (brake and tire wear), road-surface abrasion, and resuspended road dust. Pb emerged as the most diagnostically informative element for localized contamination, with exceedances of commonly used benchmark ranges at selected localities, while Cd, Cr, Cu, Fe, and Zn in washed leaves were broadly consistent with commonly accepted background ranges reported for comparable contexts. Overall, the coherent site-dependent enrichment in plant compartments, combined with paired-soil correspondence and strong leaf-deposition signals, supports R. pseudoacacia var. umbraculifera DC. as an effective biomonitor for traffic-influenced urban metal pollution and a practical tool for hotspot screening and spatial risk mapping in megacity environments.
Zorluer et al. (Wed,) studied this question.