Winter wind-driven events in the Changjiang River Estuary (CJE) induce significant bubble-mediated air-sea gas exchange, critically impacting dissolved gas budgets and biogeochemical tracer applications. Based on winter observations at 10 stations in the CJE, this study employed a size-fractionated bubble model to quantify air-sea fluxes of N₂, O₂, and Ar, systematically evaluating biases in traditional diffusive-only model estimates. We focus on elucidating the fundamental divergence in physical synchrony between N₂ and O₂/Ar during bubble transfer and vertical mixing processes, and extend the analysis to dual water-column and sediment-water interface models to clarify the critical role of bubble correction in bottom water age assessment and denitrification rate constraints. Results demonstrate that bubble processes contribute to N₂ and O₂ supersaturation with marked directional and kinetic differences. For N₂, the antagonistic effects of high atmospheric partial pressure and low solubility result in opposing flux directions for small-bubble injection and large-bubble escape, yielding consistently negative total bubble fluxes. Surface physical deviations reach 16.6–23.0 μM (~4% of saturation), while bottom values are 2.6–6.9 μM (~1%); winter wind-driven bubble degassing represents the dominant pathway for N₂ sea-to-air release. For O₂, bubbles exhibit bidirectional exchange at the surface, with physical corrections ranging from −3.9 to 6.2 μM, with most stations showing bubble injection-induced supersaturation enhancement; the bottom layer shows net dissolved input (mean ~1.2±0.24 μM). Ar essentially maintains physical equilibrium, robustly validating its role as a synchrony tracer. Following physical correction, NCP derived from ΔO₂/Ar′ converges across the entire domain with the spatial coefficient of variation decreasing from 87.3% to 19.6%, effectively isolating physical interference. In contrast, ΔO₂/N₂′ exhibits systematic deviations at u₁₀ > 7 m s⁻¹ due to the asymmetric nature of N₂ bubble fluxes violating the physical synchrony assumption. This methodological boundary indicates that ΔO₂/Ar should be prioritized as the tracer of choice for NCP estimation in high-energy estuarine environments. Comparative analysis of benthic N₂ fluxes at the water column and sediment-water interface reveals spatially coupled divergence in denitrification intensity. North and south of the CJE mouth, bottom N₂ supersaturation is dominated by water-column denitrification with sufficient water age for steady-state accumulation of biological signals; near the mouth, advective dilution significantly shortens water mass residence time, preventing ΔN₂ from reaching equilibrium with denitrification rates and diluting biological signals through physical transport. Neglecting bubble contributions to bottom N₂ supersaturation leads to a systematic overestimation of bottom water age (τ) by 28.5±9.9%. Differences in δ¹⁸O-O₂ and δ¹⁵N-N₂ between surface and bottom layers reveal bubble injection modulation effects on apparent fractionation. Surface bubble injection dilutes respiration-enriched ¹⁸O signals with dilution intensity exceeding apparent fractionation; although benthic biological source fractionation possesses extreme potential, biochemical coupling in series with physical bubble suppression prevents effective expression of this fractionation intensity in the water column, ultimately yielding observed bottom δ¹⁵N-N₂ values of only 0.36–0.54‰. This study emphasizes the necessity of synchronously coupling water age simulation, size-fractionated bubble exchange parameterization, and gas-specific isotope fractionation coefficients in high-energy estuarine and coastal regions to correct nitrogen loss flux and primary productivity estimation biases caused by physical dilution, providing methodological constraints and physical benchmarks for research on non-equilibrium dissolved gas distributions, nitrogen cycling, and carbon-nitrogen coupling in coastal seas.

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