Distribution and Fractions of Phosphorus and Nitrogen in Surface Sediments from Dianchi Lake, China

Dianchi Lake is one of the most three seriously eutrophic lakes in China. In the present study, the phosphorus (P) and nitrogen (N) fractions in 37 surface sediments samples collected in the Dianchi Lake were investigated. The total phophorus (TP) in sediments was divided into two parts: inorganic P (IP) and residual P (Res-P). The results showed that the total phosphorus content in surface sediments ranged from 1465.27 to 3650.12 mg/kg, IP was the major component of TP and the Ca bound P was the main fraction of IP. The bio-available phosphorus (BAP) in Dianchi Lake was first estimated in this study. BAP ranged from 215.66 to 678.02 mg/kgand the mean concentration was 382.78±89.77 mg/kgfor all 37 samples. The nitrogen fractions for the whole Dianchi Lake were firstly studied. It was shown that the sediment had been an important N nutrient source of the water, owing to the high content of transferable nitrogen forms in the sediment.