Assessment of heavy metal pollution in the surrounding area of the cement and smelting factories, SE Tehran, and its relationship to physico-chemical soil parameters

The total concentrations of six elements (Pb, Cu, Zn, Ni, Cr and Co) were determined in soil samples from surrounding of Tehran cement and smelting factories. The samples were analyzed by XRD analysis. The abundance of heavy metals, measured in these soils, decreases as follows: Pb > Zn > Cr > Cu > Ni >> Co. The relationship between concentration of each heavy metal and different parameters such as soil pH, type and amount of clay, organic matter, cation exchange capacity (CEC), amount of calcium carbonate and iron and aluminum oxides contents were determined. Any parameter can be detected as clearly related to each heavy metal content but Fe-oxides, Al-oxides, clay content, pH significantly and SiO2, sand percent and CEC to a lesser extend have most influence to heavy metal absorption. The results indicate high levels of Pb pollution, low to moderate levels of Cu and Zn pollution in studied soils. The source of these elements are found to be of anthropogenic origin. These soils are unpolluted with respect to Ni, Cr and Co. These elements are originated from the natural sources.