Seasonal Flux Dynamics and Internal Control Strategies of Sediment Nutrient Release in a Heavily Polluted Inflow River of Chaohu Lake

Abstract

Quantifying internal nutrient loading in hyper-eutrophic riverine systems remains central yet challenging for watershed restoration, particularly where massive external reductions unmask complex sediment-water feedback loops. This study investigated the seasonal diffusive fluxes of total nitrogen and total phosphorus across the sediment-water interface of the Shiwuli River, a heavily polluted tributary of Chaohu Lake, navigating initial experimental challenges regarding volatile boundary layer disturbances during core incubations. The observed flux variations revealed pronounced summer peaks, driven primarily by elevated temperatures, though alternative interpretations involving seasonal stormwater deposition anomalies and microbially-mediated redox shifts cannot be entirely disregarded. While conventional physical dredging exhibits immediate remediation capacity, long-term efficiency seems bound to complex re-deposition kinetics, suggesting that a singular technical intervention is unlikely to yield sustainable control. Considering these interconnected dynamics, future restoration paradigms must shift toward adaptive, multi-barrier in-situ passivation schemes paired with hydrological manipulation, though further field-scale verification remains highly necessary to refine ecological predictive capacities across wider lacustrine networks.