Effectively mitigated eutrophication risk by strong biological carbon pump (BCP) effect in karst reservoirs.

Karst reservoirs can significantly enhance the effect of biological carbon pump (BCP), a crucial process for carbon sequestration, water purification, and eutrophication mitigation. However, the effects of BCP on the fate of carbon (C), nitrogen (N), and phosphorus (P) and its role in regulating eutrophication within river-reservoir systems, remains insufficiently understood, particularly across different geological settings. We investigated the Hongfeng Reservoir (HFR), a typical karst reservoir, analyzing water chemistry, nutrient concentrations, and stable isotopes of dissolved inorganic carbon (δC) and nitrate (δN-NO) to uncover the underlying mechanisms governing the migration of biogenic elements and the process of eutrophication.