| Summary: | Rivers play a crucial role in connecting terrestrial and fluvial systems. Over the recent decades, the world’s rivers are exposed to unprecedented climatic and anthropogenic perturbations and are becoming significant sources of the atmospheric greenhouse gas (GHG) emissions. The cold temperate zones across the world, which are increasingly sensitive to temperature variations, experience notable changes in the riverine GHG emissions. However, until recently, there has been very little understanding of the GHG emissions where river system is interacted tundra forests. The GHG emissions emanating from the Changbai Mountain (CBM) area in the temperate China, are predominantly concentrated within the forest soil and tundra ecosystems. We investigated the GHG emissions from the Erdao River system in CBM using in situ gas flux monitoring technique at the water-gas interface at eight sampling sites between July and September (2022). The results indicate that GHG fluxes peaked in August, with CO 2 emissions in the CBM region were lower than in other cold-temperate areas (-1234.19~1073.60 mg·m −2 ·d −1 ) due to concentrated precipitation and high altitudinal gradients. CH 4 emissions are concentrated in nature reserves and floodplains, whereas rivers near urban areas at the foothills of CBM exhibit elevated N 2 O emissions (2.49~3.31mg·m −2 ·d −1 ) because of urbanization. The heterogeneity in GHG emissions across the sites is correlated with water quality parameters, with temperature significantly affecting the N 2 O emissions, which are the primary contributor to global warming potential (80.25%) in the river system. Organic matter sources in CBM river system are predominantly terrestrial, with a minor contribution from sea ice reservoirs. The intensified precipitation during the summer season increased the influx of terrestrial organic matter, thereby affecting GHG discharges. This study provides empirical evidence for precise quantification of GHG emissions in the cold temperate zone of China. Identifying emission ...
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