Geographic gradients reshape dissolved organic matter activity to regulate microbial metabolic strategies and greenhouse gas production across alpine aquatic systems

Abstract As a sensitive region of global climate change, the Qinghai‐Tibet Plateau is experiencing permafrost degradation, leading to the release of sequestered carbon and nitrogen into aquatic ecosystems. However, the spatial heterogeneity and underlying drivers of greenhouse gas concentrations across diverse water body types remain unclear. Here, we investigated the concentration patterns of greenhouse gases (CO 2 , CH 4 , and N 2 O) in rivers, lakes, and thermokarst lakes along an elevational gradient of 4382 m on the plateau. Results showed that mean CO 2 , CH 4 , and N 2 O concentrations were 74.39, 0.67, and 0.065 μ mol L −1 , respectively. Rivers exhibited the highest CO 2 , thermokarst lakes the highest CH 4 , and N 2 O followed a lakes > thermokarst lakes > rivers pattern. The concentrations of CH 4 and N 2 O declined with elevation, especially in lakes. Mechanistic analyses revealed that complex macromolecules, especially highly unsaturated and phenolic compounds, were closely involved in microbial carbon and nitrogen cycling. Dissolved organic matter meta‐metabolomics further indicated a high proportion of lignin compounds within the active dissolved organic matter pool, suggesting that these traditionally recalcitrant molecules play a more dynamic biogeochemical role in alpine waters than previously recognized. Moreover, microbial life‐history strategy analyses demonstrated that communities adapt to variations in dissolved organic matter bioavailability by shifting metabolic priorities from central metabolism toward polymer degradation. Our findings elucidate how macro‐geographic gradients shape the spatial patterns of greenhouse gas by driving microenvironmental differentiation. These insights have important implications for predicting future trajectories of carbon and nitrogen cycling on the plateau and for informing adaptive management strategies in fragile alpine ecosystems.