# Characteristics and Release Risk of Phosphorus from Sediments in a Karst Canyon Reservoir, China
Ye-Lin Feng
1 School of Geography and Environmental Science/Karst Research Institute, Guizhou Normal University, Guiyang 550025, China; [EMAIL_ADDRESS] (L.-Y.Y. ); [EMAIL_ADDRESS] (L.W. ); [EMAIL_ADDRESS] (Y.-J.L. ); [EMAIL_ADDRESS] (M.Y. ); [EMAIL_ADDRESS] (M.Y.-L.F.); [EMAIL_ADDRESS] (Z.-X.W.) Ye-Lin Feng
1 School of Geography and Environmental Science/Karst Research Institute, Guizhou Normal University, Guiyang 550025, China; [EMAIL_ADDRESS] (L.-Y.Y. ); [EMAIL_ADDRESS] (L.W. ); [EMAIL_ADDRESS] (Y.-J.L. ); [EMAIL_ADDRESS] (M.Y. ); [EMAIL_ADDRESS] (Z.-X.W.) [PERSON]
1 School of Geography and Environmental Science/Karst Research Institute, Guizhou Normal University, Guiyang 550025, China; [EMAIL_ADDRESS] (L.-Y.Y. ); [EMAIL_ADDRESS] (L.W. ); [EMAIL_ADDRESS] (Y.-J.L. ); [EMAIL_ADDRESS] (M.Y. ); [EMAIL_ADDRESS] (M.Y.-L.F.); [EMAIL_ADDRESS] (Z.-X.W.) [PERSON] the water column. The variations in content and distribution characteristics of different forms of inorganic phosphorus have varying degrees of influence on the release of phosphorus from sediments [3; 8; 9; 10; 11]. Therefore, it is crucial to investigate the spatial distribution and biogeochemical bonding characteristics of different phosphorus forms in reservoir sediments. This research is essential for a scientific assessment of the risk of phosphorus release from sediments and effective prevention and control of eutrophication in reservoirs [12]. Karst canyon reservoirs are characterized by a deep \"V\"-shaped valley, a narrow reservoir, large water depth, high levels of dissolved solids, high calcium concentration, and high alkalinity [13]. The environmental conditions of production and consumption in the aquatic ecosystem of karst canyon reservoirs differ from those of shallow reservoirs in the plains, resulting in a unique pattern of nutrient transport and transformation The water column in a karst canyon reservoir exhibits stratification, and the low temperature of the bottom water hinders the release of endogenous phosphorus. However, improper reservoir operation can easily lead to the release of endogenous phosphorus, leading to the enrichment of nutrients such as nitrogen and phosphorus in the water and the occurrence of cyanobacterial blooms. Enhancing the anaerobic conditions at the bottom of the reservoir, such as increasing the frequency and intensity, can promote the release of bioavailable phosphorus, which may result in the deterioration of water quality. In recent years, scholars have paid extensive attention to the research on the water ecosystem of canyon-type reservoirs in karst areas. With the continuous deepening of research on the water environment of karst canyon reservoirs, domestic and foreign scholars have accumulated rich research results. Research mainly focuses on topics such as aquatic ecology [14; 15; 16; 17; 18], the carbon cycle [19; 20; 21; 22; 23; 24; 25], microbial community structure [26; 27; 28; 29; 30; 31; 32; 33], and contamination with metals [34; 35; 36; 37; 38]. However, there is a lack of research on the forms of phosphorus and the associated release risks from sediments in karst canyon reservoirs. Consequently, our understanding of phosphorus pollution in karst reservoirs resulting from sediment phosphorus release is currently limited, hindering effective mitigation efforts. To address this research gap, our study investigates the forms and distribution of sediment phosphorus at the Wanfeng Reservoir, a typical karst canyon reservoir in China. By providing insights into sediment phosphorus dynamics, this study serves as a foundation for integrated phosphorus management in karst canyon reservoirs, with the overarching goal of preserving water quality and ecosystem health.