Phosphorus fractions in sediments from rivers around Chaohu Lake

Eutrophication has become one of the most critical water problems in China. Phosphorus (P) is a limiting nutrient for eutrophication, but sediments generally act as a source of P. The common method of identifying P forms in sediment is the fractionation approach. Concentrations, forms of P in surface sediments of inflowing rivers of Chaohu Lake were examined using a sequential chemical extraction procedure. Results showed that the values of total phosphorus (TP) and inorganic phosphorus (IP) were 344-1818 mg/kg and 161.7-1743.2 mg/kg. IP was the main P fraction in the sediments. As a whole, P fraction in sediments of rivers of Chaohu Lake was in the following order: Fe-P > Ca-P > Al-P > RS-P > L-P. However, P fraction in Nanfei River was in the following order: Fe-P > Al-P > Ca-P > RS-P > L-P. Bioavailable phosphorus (BAP) ranged from 256.7 to 1686 mg/kg and the ratio of BAP to TP was from 53.9% to 76.4%. Fe-P was an important factor to influence P bioavailability and forecast environmental risk in main rivers of Chaohu Lake.