Abstract: Sediment cores were taken from two lakes (Dianchi Lake and Hongfeng Lake) with different degree of eutrophication to analyze the contents of total phosphorus (TP), phosphorus (P) fractions, and biogenic silica, compare their profile distribution characteristics, and approach the relationships of these distribution characteristics with the evolution of eutrophication. The results showed that the residual-P and organic-P (Or-P) in Dianchi Lake accounted for 50.5%-80.8% of TP, being the main fractions of the TP, while the Or-P in Hongfeng Lake accounted for 53%-60.9% of TP, contributing more to the TP. The phosphorus fractions in the two lakes had a trend of decreasing with increasing sediment depth. The rapid increase of TP, Or-P, and Al-P contents in the two lakes and of residual-P in Dianchi Lake revealed that the P pollution of the lakes was mainly from the people’s living and production activities. The biogenic silica content in the sediments represented increasing from the bottom to the top, and decreasing in the top. The distribution characteristics of Or-P, Al-P, Fe-P, residual-P, and biogenic silica could better reflect the evolution and the present status of lake eutrophication.

Key words: Fertilization, Phosphomonoesterase, Phosphodiesterase, Phosphotriesterase, Meadow brown soil