Evaluation of the level of pollution and potential ecological risk of some heavy metals in surface soils in the Ahvaz oil-field

Background and The aim of the present study was to investigate the concentration, enrichment factor, Nemrow integrated pollution index, and potential ecological risk of heavy metals including (Pb, Ni, Cu, Zn, Cd, V and Cr) in surface soils of Ahvaz oil filed.
For this purpose, 49 soil samples with a systematic scheme from Ahvaz oil field were analyzed by atomic absorption method.
The mean concentration of heavy metals was as follow: Pb (251.20), Ni (94.6), Cu (75.80), Zn (132.84), Cd (0.69), V (4.97) and Cr (141.48) (mg/kg). The average value of enrichment factor in the soil samples decreased as Pb>Ni>Cu>Cr>Zn>Cd>V. Nemrow integrated pollution index (NIPI) indicated high level of pollution for the studied heavy metals except V. The Potential ecological risk of the studied heavy metals showed a low potential ecological risk for V, Cd, Zn and Cr; Cu showed a moderate risk and Ni and Pb indicated a considerable ecological risk. The mean value of the risk index indicated that 27 (55.10%) of the soil samples with a moderate risk, 21 (42.85%) with a considerable risk and one sample (2.05%) with a high ecological risk.
The obtained results from the enrichment factor, Potential ecological risk, and risk index indicated that the main source of heavy metals in the study area were anthropogenic sources such as oil drilling activities.