Multi-index assessment of heavy metal accumulation and associated ecological-human health risks in fish and sediments adjacent to coal-fired power plant

• Ni was the dominant metal in sediments (63.79±4.46 mg/kg), with Cd and As exceeding shale. • Risk indices showed negligible threats in sediments, except for elevated Cd levels. • In fish, Cu was most abundant (8.07±3.95 mg/kg), with As exceeding permissible limits. • Penaeus monodon and omnivores showed the highest metal content among fish species. • PCA linked power plant proximity to elevated metals in sediments and specific fish species. Coal-fired power plants are major sources of heavy metal pollution, yet their ecological and human health impacts remain underexplored in coastal regions of developing countries. This study applied an integrated multi-index framework to evaluate contamination status, ecological and human health risks, and pollution sources of six heavy metals (Pb, Cd, Cr, As, Ni, Cu) in sediments and ten important fish species from a river adjacent to coal-based power plant. Sediment analysis revealed high levels of Ni (63.79 ± 4.46 mg/kg), with Cd (0.55 ± 0.09 mg/kg) and As (16.92 ± 5.18 mg/kg) exceeding background values. Contamination Factor (CF) values ranged from 0.48 to 2.25, indicating moderate to considerable contamination, while the Pollution Load -Index (PLI) averaged 0.77, suggesting moderate pollution. Potential ecological risk (PER) values for Pb and As declined with distance from the power plant, indicating spatial dilution of contamination. In fish, Cu (8.07 ± 3.95 mg/kg) and As (1.86 ± 1.38 mg/kg) were predominant metals, with As surpassing recommended safety limits. Species-specific differences were evident, with benthic and omnivorous taxa showing higher accumulation. Estimated Daily Intake (EDI) values were greater in children (Cu: 28.26 µg/kg/day), while Target Hazard Quotient (THQ) and Hazard Index (HI) values for As in Mystus gulio exceeded unity, indicating potential non-carcinogenic risks. Carcinogenic Risk (CR) values were within or slightly above acceptable limits. Multivariate analysis, principal component analysis (PCA) and correlation analysis identified power plant emissions as the major source of contamination, evidenced by the highest metals level in adjacent sites (S1, S2) and in benthic species. Graphical abstract : This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.