Distribution of heavy metals in water and sediment of an urban river in a developing country: A probabilistic risk assessment

Abstract River water and sediment embody environmental characteristics that give valuable eco-environmental information. Due to rapid industrialization, the aquatic environment of any urban river can be seriously polluted by heavy metals (HMs). The global concern is caused by heavy metal pollution because of its potential harm to aquatic ecosystems and human health. In the Bhairab River, Bangladesh, surface sediment, concentrations of globally alarming toxic metals such as arsenic (As), chromium (Cr), cadmium (Cd), and lead (Pb) were measured to determine the ecological and human health risks of the riverine ecosystem. The average As, Cr, Cd, and Pb concentrations in water were 3.55, 31.74, 1.44, and 23.82 μg/L, respectively, and in sediment were 4.13, 34.17, 1.66, and 25.46 mg/kg, respectively. During the winter, metals in sediment were higher than during the summer. For most sediment samples, the enrichment factor (EF), contamination factor (CF), geoaccumulation index (Igeo), pollution load index (PLI) of As, Cr, Cd, and Pb indicated moderate contamination. The potential ecological risk (PER) in sediment followed the descending order of Cd > As > Pb > Cr. The contamination level of toxic metals implied that the condition is frightening and probably severely affecting the aquatic ecology of this riverine ecosystem.