Bridging ecosystem and human health: distinct neonicotinoids accumulation drivers and human exposure pathways in a multifunctional reservoir

Multifunctional reservoirs are critical environmental nexus points under constant threat from chemical contamination. In this study, the risks of neonicotinoid insecticides (NEOs) were investigated from a "One Health" perspective, linking agricultural pollution to human exposure via drinking water and fish consumption. Widespread contamination was confirmed across the water-sediment-fish system, with spatiotemporal dynamics mechanistically linked to compound-specific properties and seasonal agricultural inputs. Significant ecological risks were quantified (max ΣRQ = 18.77 in environmental media, max ΣRQ = 33.4 in fish), peaking in an agricultural tributary hotspot and wild catfish (Silurus glanis). A probabilistic human health risk assessment confirmed drinking water as the predominant exposure pathway, identifying children as the most vulnerable group. Crucially, advanced Piecewise SEM modeling delineated fundamentally divergent bioaccumulation drivers: accumulation in wild fish was governed by aqueous concentrations, whereas farmed fish exposure was dominated by Water Temperature and external, unmodeled inputs (commercial feed). This mechanistic divergence offers a refined, target-specific predictive tool for risk management. The findings provide a critical scientific basis for the implementation of season-specific monitoring and source regulation to protect both human health and vital ecosystem services.