Temperature interval specificity dominates carbon flux regulation at Lake Bosten in the arid region

Bosten Lake, the largest inland freshwater lake in China’s arid northwest, located in the Tarim River Basin, Xinjiang. This study quantified CO 2 and CH 4 diffusion fluxes using multi-season observations (2023–2025) and examined how water temperature intervals and ion composition interact to regulate carbon fluxes in an arid-region lake. Mutual information analysis and multiple linear regression were applied to identify key drivers across cold (20 °C) water temperature regimes. Bosten Lake acted as a net carbon sink during ice-covered periods, with average CO 2 uptake of 141.02 mg·m⁻²·d⁻¹ , challenging the conventional warm-season-centric view of arid-region lakes as perennial carbon sources. The moderate water temperature (WT) range (9–20 °C) dominated flux regulation, where CH 4 fluxes were best explained by a synergistic “WT– SO 4 2 − –Mg 2 + ” pathway (adjusted R 2 =0.569). Annually, the lake’s emissions offset ∼22.6% of the basin’s carbon sink, underscoring its role as a dynamic carbon node in arid landscapes. These findings highlight temperature-interval-specific mechanisms and the importance of winter processes in arid-lake carbon budgets. • Bosten Lake acts as a winter CO 2 sink under ice. • Water temperature drives CH 4 flux. • Bosten Lake offsets ∼22.6% of basin carbon.