Assessing the uptake and accumulation of heavy metals and particulate matter from ambient air by some tree species in Isfahan Metropolis, Iran.

The main scope of this study is to evaluate the uptake and accumulation potential of heavy metals in unwashed and washed leaves and particulate matter (PM) in leaf surfaces plus waxes of different tree species in Isfahan city. The highest mean concentrations of Cd, Cr, and Ni in unwashed and washed leaves were detected in M. nigra, Zn and Cu in P. fraxinifolia, and Pb was related to P. orientalis. The highest and lowest mean total depositions of total particulate matter (sum of PM, PM, and PM) were found in the leaf of M. nigra (190.23 ± 23.5) and S. alba (11.9 ± 4.42 μg/cm), respectively. The maximum bio-concentration factor (BCF) of Cd, Pb, and Ni was observed in Morus nigra; Cu and Zn in Pterocarya fraxinifolia, with the BCF of Cr found in Acer negundo. Comprehensive bio-concentration index (CBCI) and metal accumulation index (MAI) were applied for comparing different tree species in HMs accumulation from soil and ambient air. The highest CBCI was measured for M. nigra (0.86), so this tree has the potential to remediate metals from the polluted soil. Higher MAI values in washed and unwashed leaves were found in S. alba (6.77 and 6.98) and M. nigra (5.93 and 5.62), demonstrating the high capability of these trees for controlling air born-metal pollution. Based on the AOM factor, M. nigra, P. fraxinifolia, U. umbraculifera, P. fraxinifolia, A. altissima, and M. alba trees had the highest ability to capture Cd, Zn, Cu, Ni, Pb, and Cr from air. So, planting these trees would be beneficial in sensitive and critical zones such as industrial and urban areas with such atmospheric pollutants.