Forms of Phosphorus in Sediments from Hongze Lake

An improved method called seven-step sequential extraction was used to analyze all the forms of phosphorus in sediments from nine sampling sites of Hongze Lake. The results showed that the concentration of total phosphorus (TP) in sediment from Hongze Lake ranged from 580.7mg/kg~1447.7mg/kg.The main part of TP was inorganic phosphorus (IP), which contributed 64.32%~88.60% of TP, while organic phosphorus (OP) accounted for 11.40%~35.68% of TP. The maximum concentrations of TP, IP and OP were all detected in Linhuai town due to the discharge of river nearby and human activities.The main form of IP was De-P which contributed 23.58%~55.54% of TP, followed by Fe-P, which contributed 9.97%~41.33% of TP. The concentrations of Ca-P, Al-P and Ex-P were relatively low, and concentrations of Oc-P were the lowest. The vertical profiles of phosphorus forms were different in sediments from different sampling sites due to the structure and movement of the lake sediment.