Environmental Impact Assessment of Heavy Metals Pollution in the ‎Surface Soil Surrounding the Shwan Private Oil Refinery, Northeastern‏ ‏Kirkuk

Abstract

The current study included finding the concentrations of heavy elements (Co, Ni, Cu, As, Zn, Cd and Hg) in the surface soil and studying the environmental effects of Shwan Refinery within Kirkuk Governorate. Twenty surface soil samples were collected with a depth of 0-20 cm. The samples were prepared in the laboratory and sent to the laboratories of the Geology Department at the Faculty of Engineering, Ankara University for the purpose of conducting chemical analyzes using Inductively Coupled Plasma-Mass Spectrometry (ICP-MS). The results of heavy element concentrations in the surface soil of the Shwan Refinery showed that the mean value of Co, Ni, Cu, Zn, As, Cd, and Hg was 33.99 mg/kg, 149.33 mg/kg, ‎24.62 mg/kg, ‎‎57.44 mg/kg, 6.18 mg/kg, 0.04 mg/kg, 0.95 mg/kg, respectively. The analyzes of heavy elements in the volumetric fractions (sand, silt and clay) indicated that most of the heavy metals increased their concentrations in the clay fraction (Cd, As, Zn, Cu, Ni, Co) with a value of (1.13 mg/kg 9.23 mg/kg ,87.15mg/kg ,35.23 mg/kg ,189.2 mg/kg ,48.02 mg/kg) respectively. Except for mercury, which was concentrated in the coarse sandy part, whose value reached (49.4 mg/kg), may be due to the role of clay minerals that are characterized by the processes of ion exchange, absorption and deposition of heavy elements on their surfaces compared to the alluvial and sandy fractions. The geo-accummelation index (Igeo) in the study area showed that there is high pollution with the elements Co and Ni and the average pollution index for the elements a As and low pollution with the Zn, Cu, (Cd) and (Hg) which are attributed to the wind and to the public road and the parallel road for transporting petroleum products.