Geo-accumulation and enrichment of trace metals in sediments and their associated risks in the Chenab River, Pakistan

• Ecological risk assessment of trace metals in the sediments of the Chenab River
• EF, Igeo and MPI were used to evaluate the natural and anthropogenic load in the Chenab River.
• EF and Igeo values indicated that Cd and Pb may pose a potential risk to aquatic biota.
• Urban/industrial area influenced the pollution sources of toxic metals.
• Depth-wise ascending order of metals predicated historical contamination of toxic metals

In this study the level of toxic metals (Mn, Zn, Pb, Cd, Co, Cu) was determined in sediment samples from the Chenab River, Pakistan. The potential toxicity of studied metals was determined by evaluating enrichment factor (EF), geo-accumulation index (Igeo) and metal pollution index (MPI). Considering the spatial distributional patterns, the metal concentrations were higher at Trimmu Headwork site followed by Pujnad, Khanki, Marala and Qadirabad Headwork sites. Unusual higher concentrations in the deeper sediments were observed, suggesting a historical deposition of the investigated metals in the area. The Igeo and EF values revealed that sediments in this study were considerably polluted by Cd and Pb and moderately polluted by other metals. Evaluation of metal toxicity based on mean probable effect concentration PEC quotient confirmed that the Chenab River is seriously contaminated with Cd and Pb. Results of the spatial distribution pattern revealed that rapid industrialization and urbanization nearby the study area were probable sources of metal pollution. Proper measures should be taken by industrial units to ensure appropriate treatment of wastewater before disposing the toxic effluents into nearby tributaries. Government authorities must ensure strict enforcement of the National Environmental Quality (NEQ) standards of municipal and industrial effluents to save the Chenab River from further degradation.