Spatial distribution of phosphorus forms and the release risk of sediments phosphorus in West Lake, Hangzhou, China

Phosphorus (P) forms and the release risk in sediments were studied in West Lake, Hangzhou, China. The results of P forms being evaluated show that inorganic P (IP) accounted for 40.37-75.27% of the total P (TP), organic P (OP) accounted for 24.74-61.79%, IP was present at the highest levels. P bound to aluminum (Al), iron (Fe), and manganese (Mn) oxides and hydroxides (Fe/Al-P) accounted for 15.41-47.39% of the TP, calcium-associated P (Ca-P) was accounted for 8.33-49.69% and kept at a comparatively steady level. The P release risk of the sediment was evaluated through the P sorption index (PSI) and degree of P saturation (DPS). The results showed that the concentration of P in the sediment was mainly related to the active iron-aluminum oxides content. The PSI was varying in different areas of West Lake, mainly related to the ecological adversity. We concluded that the release of P in sediments of the West Lake was at a high release risk after comprehensive considering the various related factors. Moreover, submerged plants restoration was regarded as an effective method to control endogenous P pollution in West Lake, Hangzhou, China.