Potential soil pollution by heavy metals in Kurdistan region, western Iran: the impact of ultramafic bedrock

Abstract

Ultramafic rocks of the ophiolitic complexes are prone to alteration and degradation, and therefore, ease of mobility of heavy metals such as nickel (Ni), chromium (Cr), cobalt (Co), lead (Pb), and vanadium (V), resulting in environmental hazards. The ultramafic rocks of the ophiolitic realm of Kurdistan province, west of Iran, show field and compositional evidence for such hazardous conditions. The ultramafic rocks are extremely rich in Mg, Fe, Ni, Cr, and Co and they are severely altered and decomposed, resulting in the formation of Serpentine minerals including chrysotile (white asbestos). Comparison of the heavy metal concentrations with standard data indicates that the samples are enriched in Ni, Cr, Co, and V. Natural processes such as alteration and anthropogenic factors such as mining, facilitated the release and mobility of these heavy metals. For reactive contaminant species, attenuation of the pollutant transport occurs by various processes including chemical precipitation, sorption, redox reactions and changes in pH.