Author(s): Dan Zhang; Jingjie Feng; Yufei Bao; Yuchun Wang; Ran Li
Linked Author(s): Jingjie Feng, Ran LI
Keywords: Cascade reservoir Jinsha River dissolved inorganic carbon (DIC)
Abstract: The carbon cycle in large reservoirs is a complex and slow process, with the concentration distribution of dissolved inorganic carbon (DIC) significantly influenced by vertical stratification of water bodies. This study focuses on analyzing the biochemical process characteristics of DIC in deep and large reservoirs with different regulation types, particularly in the high-rainfall area of the lower Jinsha River. The study found that abundant rainfall in this area leads to a large influx of DIC and Ca2⁺ into reservoirs from rock weathering, making calcite precipitation the primary biochemical process of DIC. However, this process exhibits variability across different reservoir types and seasons. Specifically, calcite precipitation is more significant in reservoirs with above-seasonal regulation during the wet season (53.85%), while it is more pronounced in below-seasonal regulation reservoirs during the dry season (51.86%). Additionally, there are differences in calcite precipitation among different regions within the same season. During the dry season, photosynthesis becomes the second major biochemical process, especially in the Xiangjiaba (XJB) reservoir (22.22%). Meanwhile, organic matter decomposition plays a crucial role as the third major biochemical process for DIC in both wet and dry seasons. Notably, below-seasonal regulation reservoirs like XJB show relatively weaker organic matter decomposition. Although calcite dissolution is insignificant across all stations, the long-term dynamic balance between calcite dissolution and precipitation warrants attention. The findings of this study not only deepen our understanding of the carbon cycle in Jinsha River cascade hydropower stations but also provide important scientific insights for sustainable river ecosystem management. Future research should continue to explore the carbon cycle characteristics of reservoirs with different regulation types to better guide the protection and management of river ecosystems.
Year: 2025