Assessment of Heavy Metal Contamination and Ecological Risks in Sediments of the Buriganga River, Dhaka, Bangladesh

The untreated industrial waste and sewage have been severely polluting the Buriganga River. The primary sources of these heavy metals are industries including metallurgy, tanneries, electroplating and battery recycling plants. Thus, the aquatic ecosystem and health of the people who depend on this river are under threat due to this pollution. Despite some mitigation efforts, the Buriganga River remains severely contaminated. As a result, continuous monitoring, identification of sources and the implementation of mitigation strategies are required. In this study, surface sediment was collected from 12 sampling sites from both banks of the Buriganga River. The concentrations of six metals including Cr, Cd, Pb, Cu, Co and Ni were determined using an atomic absorption spectrophotometer in evaluating the level of contamination and potential ecological risks in the riverine system. To evaluate the pollution status, several contamination indices, such as contamination factor (C _f ), pollution load index (PLI), and ecological risk index (R _I ), were utilized. Results indicated severe contamination by Cd, evidenced by its high C _f value (3.916), while Pb, Cu, Co and Ni exhibited moderate contamination levels. Cr exhibited minimal contamination due to the relocation of tanning units from Hazaribagh to Savar. The presence of battery, metal-plating and metallurgy industries at site 6A is responsible for the high PLI value. Elevated PLI values at the sampling sites indicate widespread pollution. A R _I value of 151.888 indicates a moderate ecological risk, suggesting potential adverse effects on riverine ecosystems and public health. The findings underscore the need for regulatory authorities to take necessary actions to prevent direct discharge of industrial wastes and untreated sewage. Continuous monitoring of heavy metal contamination, investigation of its bioaccumulation in aquatic organisms and the development of innovative remediation methods to restore the ecological health of the riverine system should be the primary topics of future research.