Prediction of Naphthalene Attenuation Potential During River Water Infiltration: Based on the Influence of Riverine Humic Acid and Multi Factor Coupling Model

Abstract Understanding the natural attenuation of naphthalene (NAP) during riverbank filtration is critical for assessing its environmental risk under riverbank extraction. Dissolved organic matter (DOM), particularly humic acid (HA), exerts complex effects on the NAP attenuation. However, the mechanisms and magnitude to which riverine HA influences NAP attenuation during river infiltration remain poorly understood. In this study, the mechanisms and magnitude of HA on NAP attenuation during river infiltration were elucidated. The results demonstrated that the inhibitory effect of riverine HA was predominant during NAP attenuation in river infiltration. Specifically, riverine HA suppressed the natural attenuation of NAP by outcompeting NAP for terminal electron acceptors (TEAs) and reshaping microbial community structure in a manner that reduced NAP‐degrading capacity. Reactive transport simulations showed that 4.00 and 8.00 mg·L −1 HA in infiltrating river water reduced NAP attenuation rates by 1.07%–10.61% and 2.28%–18.18%, respectively. Sensitivity analysis indicated that HA‐induced interactions with Fe(III), pH, and DO significantly amplified the predictive uncertainty of NAP attenuation, underscoring the importance of incorporating coupled terms such as Fe(III) × HA and pH × HA into attenuation models. These findings enhance understanding of DOM–PAH interactions during river infiltration, providing a quantitative basis for risk assessment of NAP attenuation in dynamic subsurface systems.