[Concentration of Phosphorus in Sediments Interstitial Water as Affected by Distribution of Aquatic Plants in Dianchi Lake]

In order to reveal the effect of aquatic plants distribution on the mass concentration of phosphorus in sediment interstitial water, the mass concentrations of Dissolved Total Phosphorus (DTP), Soluble Reactive Phosphorus (SRP) and Dissolved Organic Phosphorus (DOP) in the sediment interstitial water and overlying water from areas with or without plants in the same site of Dianchi were studied. The vertical variation characteristics of phosphorus forms in sediment interstitial water were analyzed to explore the effect of aquatic plants on the phosphorus forms in sediment interstitial water. The results showed: ①Aquatic plants had an significant effect on the phosphorus mass concentration of the sediment interstitial water in different Dianchi lakes. However, they varied with different distribution sites and depth. ②Aquatic plants significantly decreased the percentage of DOP contribution in the sediment interstitial water. The average contribution of DOP with aquatic plants was 32.87%, while that without plants reached 57.68%; ③Aquatic plants significantly inhibited the release of inorganic phosphorus in sediments and promoted the transformation of DOP. The SRP diffusion flux at sediment-water interface with aquatic plants was increased by 39.99% as compared with that without plants; ④The growth of aquatic plants significantly reduced the concentration of phosphorus in sediment interstitial water, especially DOP, and the reduction rate of the sediment interstitial water DOP was from 38.02% to 85.49%. Therefore, the analysis of the contribution and reduction rate of aquatic plants on the sediment interstitial water DOP was of great importance in understanding the relationship between aquatic plants and DOP, as well as the mineralization of organic phosphorus in sediments.