Study on the Law of the Phosphorus Forms Transformation in the Sediment of Excess Alga Period Lake

Based on the experiment of the phosphorus forms and the effect factors of phosphorus release from sediment in the urban shallow lake (taking Lake Xuanwu as a example)¿the results showed that when the water body had higher pH value during the excess alga period, phosphorus in the sediment was released deeply and the total dissolved phosphorus(TDP) was increased from 0.049mg/L to 3.255mg/L as 66 times as the origin concentration. The organic phosphorus(OP) in the sediment was transformed into inorganic phosphorus(IP) and became the important phosphorus forms that influenced the phosphorus release from sediment. The results also showed that the dissolved phosphorus(DOP) and alkaline phosphate(APA) in the sediment had positive correlated with the TDP of the water, which proved that microbial hasten the process of phosphorus release from the sediment. After the excess alga period ending, the pH value of waterbody would decrease slowly, phosphorus in sediment would not release any longer and sediment would become the collection of pollutants in the water environment again.