[Simulation research on the release of internal nutrients affected by different dredging methods in lake]

A simulated experiment was carried out to study release features of internal source under different sediment dredging methods and the difference between two lake areas in Lake Taihu was also studied. The contaminated sediments were sampled from two sites in Meiliang Bay which were the Inner Bay (A) and the Outer Bay(B). Release rates of phosphorus after ideal dredging and suction dredging are about 20% and 72% of the control and the phosphorus release rate in Inner Bay(A) is about 80% of Outer Bay(B). Release rates of ammonia after ideal dredging and suction dredging are about 40% and 83% of the scallop dredging, but dredging process may even promote the release of ammonia in a short time, the ammonia release rate in Inner Bay(A) is about 150% higher than that in Outer Bay(B). Under the microcosm experiment condition, the ideal dredging method and the suction dredging method may have a better control of internal source in contrast with the scallop dredging. Altogether, sediment dredging may be a useful approach to decrease the release of internal source in the selected sites when the external nutrients are effectively controlled. Consider all kinds of dredging projects, the suction dredging should be the ideal option for sediment dredging in Lake Taihu.