Dry-wet cycling accelerates environmental transformation of emerging tungsten dust: Predictions from an atomistically based oxidation-dissolution kinetic model.

Tungsten dust from mining, military, industrial, and fusion-related sources combines a high specific surface area with repeated environmental wetting. Yet the kinetic link between oxidation, dissolution, and soluble tungstate release remains poorly constrained. Here, we develop a cross-scale coupled oxidation-dissolution model by integrating density functional theory, reactive molecular dynamics, and particle-scale rate coupling. Calculations and sensitivity analysis show that oxide growth is predominantly controlled by oxygen transport through the WO3 layer, leading to self-limiting oxidation. The oxidation model reproduces experimental from 25 to 800 °C with Rlog2 = 0.9789 and NRMSE = 3.97%. At the WO3-water interface, W release proceeds through hydration-assisted W-O bond weakening, water backfilling, and stabilization of solvated W species, with an effective barrier of 1.262 eV. The dissolution model captures non-calibration experimental data across pH, temperature, initial dust diameter, and exposure time with Rlog2 = 0.8939 and NRMSE = 11.38%. Climate simulations show that precipitation pattern rather than temperature alone controls source release, with humid subtropical dry-wet cycling producing the highest normalized tungstate release. These results show that repeated oxide growth and removal can shift deposited tungsten dust from a particulate reservoir to a source of aqueous tungstate release.