Effects of sediment-dredging on the phosphorus release from sediments in Nansi Lake

Nansi Lake, covering 1266 km² is a buffer lake of the South-to-North Water Diversion Project (east route). Phosphorus release from sediment is becoming the most serious pollutant after the allochthonous phosphorus was controlled in recent years in this lake. In this paper, simulating dreding experiment was done on the two heavily polluted sediment, namely the Guangfu esturay(GF) and the aquiculture zone(YZ). The experimental results showed that the phosphorus releasement quantity becomes slower after sediment-dreding, and sediment dredging could inhibit the release of phosphorus effectively. According to the phosphorous release results and the vertical distribution of phosphorus fractions, the optimal dredging depth at GF and YZ are 15 cm and 5 cm respectively.