Ecological Indices of the Heavy Metals in the Soil of Shewasoor Sub-Basin, Kirkuk NE Iraq

Abstract

The current research aimed to assess contamination levels in the soil of study area by heavy metals. Eight sites were selected for the collection of soil samples. The eight heavy metals namely As, Pb, Cd, Cr, Co, Cu, Ni, and Zn were analyzed in each soil samples by using ICP-MS technology. The measured concentrations of heavy metals were compared with Geochemical Background values, EPA Sediment Quality Guidelines, Ecological Screening values, and WHO Guidelines. The spatial distribution maps of ecological indices were performed using ArcGIS software (version 10.2), which provides an idea of the geographical distribution of heavy metals contamination levels in the soil of Shewasoor sub-basin. The soil contamination by heavy metals assessed using Potential Ecological Risk Index (RI), Nemerow Pollution Index (P_N), Hazard Index (HI), and Cancer Risk. The RI showed there are high risk of heavy metals in soil and according to P_N the soil has been moderate to severely contaminated by heavy metals. The hazard index of all soil samples was within acceptable range for adults and showed unacceptable risk for children. While the total cancer risk values of As and Cr were within acceptable limits, whereas of Pb, Cd, Co, and Ni were lower than acceptable risk range at all sites for adults and children. Ecological indices which are used to assess the contamination levels in the soil by heavy metals refers to the soil of study area was contaminated moderate to heavily by heavy metals, this attributed to the natural and anthropogenic pollution sources around and within the study area.