Weakening greenhouse gas sink of intermittent river under human activities for the Inner Mongolia grassland region in China

This study was conducted in the Tabu River Basin, located within the Yinshanbeilu Grassland in central Inner Mongolia Autonomous Region, China. The Tabu River's runoff is significantly affected by human activities. This study investigated the spatiotemporal dynamics of the CO 2 flux under varying runoff conditions, identified the key drivers of CO 2 emissions, and assessed the influence of human activities on these emissions within the watershed. Our findings revealed a significant decline in runoff in the Tabu River Basin since 2010, primarily driven by human activities. Following river drying, riverbed ecosystem respiration ( ER ) increased, whereas riparian wetlands exhibited a marked decrease in ER . Furthermore, net ecosystem exchange ( NEE ) results indicated a shift from a carbon sink to a carbon source in the riparian wetlands during periods of river drying. Soil moisture content (SMC), above-ground biomass (Bios), and soil bulk density (ρb) emerged as critical factors regulating CO 2 emissions. These findings highlight the necessity for continuous, long-term monitoring of intermittent rivers and in-situ greenhouse gas flux measurements under diverse hydrological conditions. To enhance the resilience of riverine ecosystems and sustain their carbon sequestration potential, future management of the Tabu River Basin should focus on optimizing irrigation strategies and adapting reservoir management practices. Such interventions will enable efficient allocation and sustainable utilization of water resources. • Human activities were the primary influencing factor of intermittent river drying. • Intermittent river CO 2 emissions controlled by runoff change. • Riparian wetland transformed from a sink to a source due to intermittent river drying. • Intermittent river drying can accelerate carbon loss from the watershed.