Potentially Toxic Elements (PTEs) in Sediment of the Upper Banar River, Bangladesh: Occurrence, Pollution Load, Source Apportionment, and Potential Risks

The Upper Banar River, a natural source of fresh water and fisheries resources in the north-central Bangladesh, has been receiving substantial attention due to the recent increase in anthropogenic interventions along the river. However, no study has yet been carried out to investigate the status of pollution and associated risks in this ecologically important river. This study used an inductively coupled plasma-mass spectrometer (ICP-MS) to analyze 30 composite sediment samples collected from 10 sites along the Upper Banar River to evaluate the pollution level, spatial distribution, ecological and human health risks of 6 potentially toxic elements (PTE) including As, Cd, Cr, Cu, Ni, and Pb. The mean concentrations of Cr, Ni, Cu, As, Cd, and Pb were 26.30, 39.75, 9.36, 0.79, 1.83, and 14.79 mg/kg, respectively, while the concentrations varied considerably within the sampling sites. Multivariate statistical analysis revealed that As, Cd, Cr, and Ni had been augmented through human activities. Sediment pollution evaluation indices demonstrated heavy contamination by Cd. The findings also exhibited considerable to extremely high ecological risks posed by PTE although the total number of toxic units across all sampling sites was intermediate to low. The study revealed that the average daily intakes of PTE were permissible exposure levels. The hazard index (HI) and total hazard index (∑HI) for adults and children across all sites showed that the risk is not statistically significant (HI > 1). The exposure to As, Cr, Cu, and Pb through ingestion as well as the exposure to Cu through dermal contact showed potential for carcinogenic risks (10⁻⁶ to 10⁻⁴) in humans. The findings clearly depicted that the Upper Banar River has been seriously contaminated with PTE of anthropogenic origins and emphasized the need of a more thorough risk evaluation of PTE in this riverine ecosystem.