A review of CO₂ fluxes from inland lake wetlands in China

Lake wetlands serve as critical carbon reservoirs and sources/sinks within the terrestrial biosphere, playing a crucial role in the global carbon cycle. China is endowed with extensive lake wetland resources, and enhancing the capability to monitor and estimate their carbon source/sink dynamics is critical for achieving the national goals of carbon peak and carbon neutrality. However, considerable uncertainties remain due to limited research on carbon flux monitoring and mechanistic understanding of carbon cycling processes in these ecosystems. To improve the understanding of carbon dioxide (CO₂) flux research in Chinese lake wetlands and enhance the accuracy of carbon source/sink assessments in terrestrial ecosystems, this review classifies inland lakes of China into five distinct regions, according to the geographical regionalization framework; they are Tibetan Plateau lakes, Eastern Plain lakes, Inner Mongolia-Xinjiang lakes, Yunnan-Guizhou Plateau lakes, and Northeast Plain and Mountain lakes. For each region, we synthesize the characteristic patterns of CO₂ fluxes and identify key drivers influencing CO₂ emissions, such as climate conditions, hydrological properties, sediment characteristics, vegetation coverage, and anthropogenic impacts. Also, we provide an overview of widely applied methodologies for monitoring and estimating CO₂ fluxes, e.g. eddy covariance systems, floating chambers, and remote sensing-based models. Furthermore, this study outlines the major challenges in current research, including spatial and temporal data gaps, methodological inconsistencies, and scaling issues from site-level measurements to regional estimates. We propose future research directions aimed at strengthening long-term monitoring networks, integrating multi-source data, developing mechanistic models, and improving carbon sequestration strategies. This synthesis is expected to offer a scientific foundation for the conservation and sustainable management of lake wetlands, as well as the enhancement of their carbon sequestration potential in the context of climate change mitigation.