[Vertical Variation of Phosphorus Forms in Lake Dianchi and Contribution to Release]

Columnar sediment samples were collected from the Waihai of Lake Dianchi in northern, central and southern sediment, combined with the data of phosphorus in the overlying water and sediment organic matter, the effects of organic matter and particle size on sediment release were studied, and the influence of different forms of phosphorus release from sediments and their contributions were discussed. The results showed:Sediment pore water ρ(DTP) and ρ(SRP) was negatively correlated with contents of OM, clay (<4.00 μm) and silt (4.00-63.00 μm), but it showed a significant positive correlation with sand (>63.00 μm) content. Theincrease in organic matter content of the sediments significantly reduced the gap water phosphorus mass concentration, and increasing clay and silt contents reduced the gap water phosphorus mass concentration, inhibiting the release of phosphorus in sediments. Potentially mobile phosphorus of the Lake Dianchi sediment was significantly positively correlated with the clay and silt contents, and was significantly negatively correlated with the sand content. It was indicated that clay and silt may enhance the phosphorus movement ability of the sediment, and the sand may enhance the retention of phosphorus in the sediment. In a short time scale, phosphorus of sediment was released mainly in northern Waihai, staying mainly in central and southern; in a longer time scale, phosphorus of sediment was released mainly in northern and central Waihai, staying mainly in southern. Control of phosphorus release from sediments in Lake Dianchi should take into account the effects of different forms of phosphorus, organic matter and particle size, and take corresponding measures to control the release of phosphorus in sediments of northern Dianchi mainly.