Heavy metals contamination in soil and food and their evaluation for risk assessment in the Zhob and Loralai valleys, Baluchistan province, Pakistan

This study determined the heavy metals (HM) contamination in soil and food of Zhob and Loralai valleys of Sulaiman fold belt, Baluchistan province, Pakistan. For this purpose, soil and food (food crops and fruits) samples were collected and analyzed for the HM using atomic absorption spectrometry (Perkin Elmer, AAS-PEA-700). Among HM, the iron (Fe) showed highest concentration in soil and food, followed by manganese (Mn), nickel (Ni) and chromium (Cr), while lowest for cadmium (Cd). Results revealed multifold higher contamination factor (CF), pollution load index (PLI) and ecological risk index (ERD values for soil in the Zhob valley as compared to Loralai valley. Plant enrichment factor (PEF) for Cr, Ni, Fe and Cu were 18.3, 13.6, 12.7 and 11.4. Elevated PEF values led to higher plant bioaccumulation factor (PBF) and resulted in the potential health risk. The HM contaminations were evaluated for daily intake of metal (DIM) and hazard quotient (HQ). Results showed that HQ values > 1 for Cd and Ni to the exposed population through food consumption in the Zhob valley. Higher risk in the Zhob valley was due to higher contamination that could be attributed to denudation of ophiolites.