EFFECTS OF VARYING ENVIRONMENTAL CONDITIONS ON RELEASE OF SEDIMENT PHOSPHORUS IN WEST LAKE, HANG ZHOU, CHINA

To understand the eco-environment effects of varying environmental factors on the transportation and transformation of sediments P and the development of West Lake sediments P release, we analyzed phosphorus (P) fractions, grain size and chemical composition of sediments in West Lake, and investigated the influence of varying environmental conditions including P concentration in overlying water, light, pH, temperature and disturbing on the release of sediment P. The results indicated that the largest release quantity of sediment total phosphorus (TP) in the distilled water was 1.15 times compared with that in sediment-water system, and the main P form were P bound to Al, Fe, and Mn oxides and oxyhydroxides (Fe/Al-P) of inorganic phosphorus (IP). The greatest release quantity of TP under no light was almost 1.35 times larger than that under illumination condition. The pH value was an important factor for the release of P from sediments, and alkaline condition promoted the Fe/Al-P release and acid condition promoted the Calcium bound phosphorus (Ca-P) release. High temperature promoted sediment P release. Various P fractions content in the sediment gradually gained equilibrium in the condition of disturbing intensity after 15h. Sediment P release amount under equilibrium disturbing condition was about 1.61 times compared with that under static equilibrium. This study provides theoretical basis for the control of internal pollution caused by sediment P release.