Nanotoxicological Assessment of Agro-Industrial Nanoparticles in Water Systems of the Niger Delta: Environmental Fate, Bioaccumulation and Ecological Risk Modelling

The proliferation of engineered nanomaterials in agricultural and industrial applications in the Niger Delta region, including titanium dioxide, zinc oxide, and silver nanoparticles from agro-industrial effluents, poses underexplored nanotoxicological risks to aquatic ecosystems and human health. This study conducted a comprehensive nanotoxicological assessment of priority engineered nanomaterials in water systems of the Niger Delta across Bayelsa, Delta, and Rivers States, integrating environmental fate modelling, bioaccumulation studies, and probabilistic ecological risk assessment. Nanoparticle characterisation in environmental matrices employed single particle ICP-MS, nanoparticle tracking analysis, and transmission electron microscopy. Environmental fate and transport were modelled using a modified SimpleBox4nano framework calibrated with local hydrological parameters. Bioaccumulation was assessed in Clarias gariepinus (catfish) and Penaeus monodon (shrimp) under laboratory-simulated field exposure conditions. Species sensitivity distributions were constructed from toxicity data to derive predicted no-effect concentrations. Titanium dioxide and silver nanoparticles were detected at ecotoxicologically relevant concentrations in 60% of sampled water bodies. Bioconcentration factors for silver nanoparticles in catfish gill tissue exceeded 400 L/kg. Monte Carlo-based risk quotient calculations indicated unacceptable ecological risk for silver nanoparticles at 35% of monitoring sites under current loading conditions. The study contributes original environmental fate modelling parameters for tropical freshwater nanoparticle transport and an ecological risk framework applicable to Nigerian regulatory decision-making. Keywords: nanotoxicology, engineered nanoparticles, Niger Delta, ecological risk, bioaccumulation.