ASSESSMENT OF CONTAMINATION OF THE INDUSTRIAL REGION SOILS CAUSED BY HEAVY METALS

Due to the advent of the industrialisation phenomenon, the increasing contamination of the soil caused by heavy metals has recently become a major concern. The present study set out to collect samples from the 0-30 and 30-60 cm depths of the soils in industrial areas for the purpose of evaluation of the contamination caused by the heavy metals through the Pearson correlation coefficients and quantitative indices. The results revealed that the Cu and Pb concentrations were higher than the average in both depths of shale like Cd at the 30-60 cm depth. Ni and Cd as well as Ni and Cu were shown to be higher in terms of the concentration values than the Iranian standard at the 0-30 and 30-60 cm depths, respectively. The mean I-geo soil was classified as uncontaminated by the Iranian standard, uncontaminated to slightly contaminated, and very contaminated to severely contaminated by the shale average associated with Pb, Cr and Cd, respectively, whereas Ni and Cu were determined to be uncontaminated. Low and moderate contamination factors were attributed to Pb, Cr, Cd as well as Ni and Cu by the Iranian standard at both depths. It was also shown that the mean contamination degree (CD) and modified contamination degree (MCD) were moderate and very low, respectively. The pollution load index was demonstrated to be uncontaminated by the Iranian standard. The mean contamination factor correlated with the average shale turned out to be classified as low, moderate, and very high factor as far as Fe, Cr and Ni, Pb and Cu, Cd were concerned, respectively. Moreover, the mean contamination degree (CD) and modified contamination degree (CD) were considerable, low and moderate, respectively. The mean pollution load index was indicative of contamination, and Enrichment factor (EF) was ranked as follows: Cd > Pb > Cu (at both depths of the average shale). Correlation values (r) attested to the common sources of Pb, Cr and Ni, on the one hand, and Cr, Cu, Ni and Cd, on the other hand, at the 0-30 cm depth.