Occurrence, sources and ecological risk assessment of per- and polyfluoroalkyl substances (PFASs) in water and sediment from urban rivers in Dhaka, Bangladesh

Per- and polyfluoroalkyl substances (PFASs) in urban rivers of rapidly industrializing regions remain understudied, particularly in South Asia. This study assessed the occurrence, sources, and ecological risks of 15 PFASs in water and sediment from three major rivers (Buriganga, Turag, Shitalakkha) in Dhaka, Bangladesh. PFASs were quantified using HPLC-MS/MS, and sources were identified via principal component analysis (PCA). All target compounds were detected, with total concentrations in water ranging from 23.96 to 89.35 ng/L and sediment from 2.18 to 11.67 ng/g dry weight. Perfluorooctanoic acid (PFOA) dominated water samples (34%-59% of ΣPFASs), reflecting its ongoing industrial use and high water solubility, while perfluorooctane sulfonate (PFOS) prevailed in sediments (up to 71% of ΣPFASs) due to historical accumulation. The Buriganga River exhibited the highest contamination, driven by untreated effluents from tanneries, textiles, and chemical industries. Risk quotient (RQ) analysis revealed low-to-moderate ecological risks for most PFASs, but PFOS in sediments posed a high risk (RQ = 1.68) near industrial clusters. Compared with global data, PFAS levels in rivers around Dhaka city exceeded those in less industrialized regions but were lower than those in heavily polluted systems. These findings highlight the urgent need for stricter regulation of industrial discharges, improved wastewater treatment, and long-term monitoring to mitigate PFAS contamination in urban waterways. This study also provides critical baseline data to inform environmental policy and sustainable water management in developing regions.