Impact Of Macrophyte On The Characteristics Of Phosphorus Release And Phosphorus Sorption In Sediments

This paper mainly analyzes the effect of internal pollution sources in Taihu on the eutrophication.Five sediments: the control and several sediments of macrophytes (Vallisneria spiralis, Phragmites comrnunis, Zizania latifolia (Griseb), Water Chestnut) from Meiliang Bay of Taihu Lake were tested in different conditions. We study the release-adsorption of phosphorus from sediments and the effecting factors. And the impact of macrophyte on the characteristics of phosphorus release and adsorption in sediments.From the analyse of physical properties of the sediments, the total phosphorus of sediments was as follows: Vallisneria spiralis to 951.8mg.kg^-1, Phragmites communis to 982.7 mg.kg^-1, Zizania latifolia (Griseb) to 825.5 mg.kg^-1, the control to 1021.3 mg.kg^-1. The organic matter content was as follows: Vallisneria spiralis to 35.81 mg.kg^-1, Phragmites communis to 29.379 mg.kg^-1, Zizania latifolia (Griseb)to 34.426 mg.kg^-1, the control to 36.305 mg.kg^-1.According to the results, several conclusions were summarized as follows:(1)Adsorption isotherms of phosphorus and the phosphate kinetic on four surface sediments taken from Taihu were determined in laboratory, meanwhile, the effect of on its phosphate adsorption characteristics was also analyzed. Adsorption isotherms of phosphorus experiment indicates that: with the increasing of phosphate concentration in the overlying water, the phosphorus adsorption capacity increased. Phosphorus adsorption was differtent on different sediments. At the same time, the phosphorus adsorption capacity in control was less than the others. The phosphate kinetic equilibrium concentration was closely correlated to total phosphorus and iron (oxy) hydroxides and organic matters. Organic matter content, Fe could play a significant role in determining the phosphorus adsorption capacity.(2)The release of phosphorus from sediments was controlled by many factors, such as DO, pH, temperature, disturbance. The simulation experiments of four sediments indicated that phosphorus release was affected by environmental conditions. The intensity of phosphorus release was increased with high temperature, disturbance and anaerobic condition.When the pH of water is acidic and alkaline condition, the intensity of phosphorus release was larger than neutral acidic.(3) The experiments of phosphorus release were controlled at different temperature and microbial conditions. The results showed that high temperature and microbial activities enhanced phosphorus release.Planting the macrophytes, such as Phragmites communis, Water Chestnut and so on, may to a certain extent reduce internal pollution of the lake sediment, which can provide some references for eutrophicated Taihu Lake and ecological remediation.