Heavy metal contamination in soils of industrial estates of Tamil Nadu, India and source identification by magnetic susceptibility

An increase in erratic industrial activity has been a major contributing factor to the significant contamination in environmental matrices. This study aimed to ascertain the level of heavy metal contamination in soils in major industrial estates of Tamil Nadu as well as the threats to human health and the environment that concomitant with it. This led to the use of the total reflection X-ray fluorescence (TXRF) spectroscopy technique to analyse 31 soil samples. Thus, the mean heavy metal concentrations were found to be in the ascending order: As < Ni < Pb < V < Cu < Zn < Cl < Mn < Sr < Cr < Al < Fe. Pb, Cr, Cu, As, and Zn have been identified as predominant contaminants in the study area using the conventional pollution indices such as geo-accumulation index (I-geo), contamination factor (CF), and enrichment factor (EF). The magnetic susceptibility measurements indicates that the percentage of frequency dependence of magnetic susceptibility of the studied soil samples varied from 0.88 to 11.15 and that represents the presence of admixture of superparamagnetic (SP) particles in the soil samples. From the results of multivariate statistical analyses, the sources of identified heavy metals were classified as anthropogenic sources (Cr, Cu, Pb, As, and Zn), natural sources (V, Mn, Fe, Ni, and Sr ), and intermediate sources (Al and Cl).