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Abstract Inland waters constitute vital components in the global carbon (C) cycle. Nevertheless, the regional patterns of aquatic carbon transfer across China remain poorly quantified, and their impacts on the terrestrial carbon budget remain unclear. Here, we quantified the three primary aquatic carbon output fluxes and evaluated their implications for China's terrestrial carbon budget. We showed that the total aquatic carbon output flux was 165 ± 20 Tg C yr −1 , counteracting 29% of China's terrestrial net ecosystem productivity (NEP). Carbon dioxide (CO 2 ) emissions from river networks (86 ± 19 Tg C yr −1 ) dominated the aquatic carbon transfer, accounting for 52% ± 13% of China's aquatic carbon output flux. Carbon burial in reservoirs (20.2 ± 3.4 Tg C yr −1 ) represented a significant anthropogenic redistribution of terrestrial carbon equivalent to 46% ± 8% of the downstream carbon export (43.6 ± 1.8 Tg C yr −1 ) across China. Furthermore, the positive correlations between aquatic carbon yield and precipitation and terrestrial NEP indicated a direct climatic control on aquatic carbon dynamics, whereas human activities have amplified these effects. Considerable spatial variations were observed in the net landscape carbon balance (NLCB) across China. Specifically, the NLCB in low‐productivity regions was sensitive to aquatic carbon transfer, whereas terrestrial ecosystem productivity exerted the dominant control in high‐productivity ecosystems. Our findings elucidate the spatial patterns and regulatory mechanisms governing aquatic carbon transfer across China, establishing a robust framework to refine regional carbon balance assessments and inform targeted climate management strategies.
Hou et al. (Mon,) studied this question.