Evaluation and risks assessment of potentially toxic elements in water and sediment of the Dor River and its tributaries, Northern Pakistan

Abstract

The present study investigated the concentrations of potentially toxic elements in water and sediments of the Dor River and its tributaries. The physicochemical parameters of water and sediment samples were investigated, including potentially toxic elements (PTEs), such as Fe, Ni, Co, Zn, Cd, Pb, Mn, and Cr. Among the PTEs tested, the highest concentration in water was observed for Fe 787 μg/L upstream and the lowest was observed for Cd 1.98 μg/L downstream. The human risk posed by the PTE concentrations in water was evaluated. The maximum CDI value was observed for Fe 48.3 μg/kg-day and the maximum HQ value was observed for Co 2.73 for children downstream owing to their water consumption. The PTE concentrations in sediments were evaluated for the quantification of pollution and the ecological risk index (ERI). The Dor River and its tributaries were classified according to the contamination factor (CF): Cr, Co, and Zn had low CF, Pb indicated a moderate CF and Cd had a considerable CF. The pollution level index values attributed to sediment concentrations were slightly higher than 1, suggesting pollution in the river. The highest and lowest ERI values in sediments were calculated for Cd of 168 and Zn 0.45, respectively. The downstream sediment of the study area posed a moderate ecological risk level to aquatic systems due to Cd.