Abstract:
Investigating the characteristics and mechanisms of soil organic carbon storage in the drawdown zone of reservoirs under periodic water level variations is of great significance for accurately understanding the eco-environmental effects of reservoirs and assessing their carbon sink function. Water level fluctuations in the drawdown zone of reservoirs could disrupt the formation and stability of soil aggregates, and also affect the binding of soil minerals and organic carbon as well as the structure and function of microbial communities, thereby regulating organic carbon sequestration. However, the soil organic carbon content in the drawdown zone is influenced by complex environmental factors, and the dominant mechanisms of soil organic carbon sequestration in the drawdown zone vary under different environmental conditions. Currently, no consensus has been reached on the storage and distribution patterns of soil organic carbon in drawdown zones under periodic inundation and exposure. Research on the soil carbon sequestration mechanisms of reservoir drawdown zones remains relatively insufficient, while it is particularly necessary to elaborate on the dynamics of organic carbon and its regulatory mechanisms in these areas. This review summarizes the impact of water level fluctuations on the storage and distribution of soil organic carbon in the drawdown zone, and analyzes the physical, chemical, and microbiological mechanisms of soil organic carbon sequestration in the context of the special hydrological features of the drawdown zones. Future research should combine field sampling surveys with in-situ controlled experiments to deeply elucidate the mechanisms of soil organic carbon sequestration and their interactions in reservoir drawdown zones, thereby providing a scientific basis for the development of carbon sequestration models and carbon sink accounting in drawdown areas of reservoir.