Abstract:

The phosphorus release of sediment can significantly prompt water eutrophication,however,its key components and controlling factors remain to be fully researched. In this paper, vertical distribution characteristics of phosphorus sorption parameters and the content of sediment organic matter (OM) and phosphorus forms from large shallow lake (Lake Chaohu) and a river entering it (the Nanfei River) were described systematically.The results suggested that ironbound phosphorus(Fe(OOH)~P) and calciumbound phosphorus(CaCO3~P) were the main forms of sediment phosphorus,and both showed significantly positive relationship with equilibrium phosphorus concentration (EPC0).Compared to Lake Chaohu,the Nanfei River had significantly higher sediment phosphorus sorption maximum(Qmax).This phosphorus buffering capacity was counteracted by higher Fe(OOH)~P content,thus showing obviously strong releasing potential (high EPC0 value).The sediment OM not only enhanced the Fe(OOH)~P and CaCO3~P content,but also gave rise to the Qmax value in linear manners,thereby controlling the EPC0.The sediment EPC0 of the Nanfei River obtained minimum value in subsurface (10-15 cm), so had relatively smaller risk of phosphorus release