Abstract
The aim of the current study is to determine the chemical properties and heavy metal content of wastewater and sludge derived from tanneries and to assess their impacts on the changes in soil profiles of tannery effluents dumpsite in terms of chemical composition of soil solution and heavy metal pollution levels. Higher values of electrical conductivity (EC) and soluble cations and anions in tannery wastewater, sludge, and soil samples were observed comparing to control samples. The results showed a great variation in the concentrations of the investigated heavy metals (Fe, Cr, and Pb) in both surface and subsurface soil layers. Highest concentrations of the metals were detected in the surface soil layer. Based on calculated contamination factor (CF) and enrichment factor (EF), soil samples are contaminated and enriched with Pb and especially Cr as a result of disposal of tannery effluents. Principle component analysis (PCA) suggests that both tannery wastewater and sludge are responsible for changing the chemistry of soil solution and inducing toxic metals into the soil environment. Therefore, the findings obtained from this study should be taken into account to understand and predict the type and degree of contaminants derived from tanneries.