Abstract: The fluctuations of water level can lead to the changes of the concentration and forms of phosphorus (P) in the riparian zone. In this study, we investigated the changes of forms and bio-availability of P in different elevations of riparian zone of Lanlinxi catchment in Three Gorges Reservoir. The mean concentration of total P was 508.48 mg·kg-1, which is lower than that of the background soil, suggesting that the submerging led to P release in the riparian zone. Detrital apatite P and occluded P were the main forms of P in Lanlinxi riparian zone. The concentrations of various forms of P were following the order: detrital apatite P > occluded P > Fe bound P > Albound P > organic P > authigenic apatite P > loosely adsorbed P. The mean concentration of bio-available P was 204.12 mg·kg^-1. Phosphorus would be released to the water body when riparian zone was submerged.

Key words: Poyang Lake urban agglomeration, bearable critical threshold of urban-rural construction land, remaining development intensity, land carrying capacity, spatial matching degree