Evaluation of potentially toxic metals pollution in the sediments of the Kor river, southwest Iran

Abstract

This study is carried out to evaluate potentially toxic metal concentrations (As, Cd, Cr, Cu, Hg, Mo, Ni, Pb, and Zn) together with their spatial distribution, degree of pollution, and potential ecological risk in Kor river sediments (southwest Iran) using sediment quality guidelines, geoaccumulation index (I geo), Hakanson potential ecological risk index (RI), and standard methods of statistical analysis. The study area stretches some 140km from the Drodzan Dam to Bakhtegan Lake, a stretch of river where different industrial and domestic activities (e.g., petrochemical complex, oil refinery, industrial meat processing complex, Marvdasht city sewage) and ecological value overlap with each other. Calculated geoaccumulation index indicate that 50% of the stations are moderately to very extremely polluted. The potential ecological risk for nine investigated metals in Kor river is Hg (948) > Mo (51.9) > Ni (37.8) > Cd (29.8) > As (22) > Cu (16.6) > Pb (13.3) > Zn (3.3) > Cr (1). Results show that sediments in parts of Kor river sediments are heavily affected by effluents discharged from industrial plants and other parts are affected by agriculture and urban runoff from nearby lands. These phenomena may cause a risk of secondary water pollution under sediment disturbance and/or changes in the physical-chemical characteristics of the aquatic system.