Relationships between magnetic susceptibility and heavy metals in urban topsoils in the arid region of Isfahan, central Iran

Recently methods dealing with magnetometry have been proposed as a proper proxy for assessing the heavy metal pollution of soils. A total of 113 topsoil samples were collected from public parks and green strips along the rim of roads with high-density traffic within the city of Isfahan, central Iran. The magnetic susceptibility (chi) of the collected soil samples was measured at both low and high frequency (chi lf and chi hf) using the Bartington MS2 dual frequency sensor. As, Cd, Cr, Ba, Cu, Mn, Pb, Zn, Sr and V concentrations were measured in the all collected soil samples. Significant correlations were found between Zn and Cu (0.85) and between Zn and Pb (0.84). The chi fd value of urban topsoil varied from 0.45% to 7.7%. Low mean value of chi fd indicated that the magnetic properties of the samples are predominately contributed by multi-domain grains, rather than by super-paramagnetic particles. Lead, Cu, Zn, and Ba showed positive significant correlations with magnetic susceptibility, but As, Sr, Cd, Mn, Cr and V. had no significant correlation with the magnetic susceptibility. There was a significant correlation between pollution load index (PLI) and chi lf. PLI was computed to evaluate the soil environmental quality of selected heavy metals. Moreover, the results of multiple regression analysis between chi lf and heavy metal concentrations indicated the LnPb, V and LnCu could explain approximately 54% of the total variability of chi lf in the study area. These results indicate the potential of the magnetometric methods to evaluate the heavy metal pollution of soils. (C) 2011 Elsevier B.V. All rights reserved.