| To assess impacts and risks of sediments dredging on water environmental quality of Wulihu Lake, the principal components analysis method and the Monte Carlo romantic sampling model were used. Five principal constituents of Wulihu lake were generalized and defined by using sixteen water quality index data, and it was studied the characteristics of the variation of every principal component and the comprehensive component with sediment dredging. The result were that during sediment dredging the water quality of Wulihu lake were more serious, and the values of the comprehensive component and the principal component F1 increased to the the highest level, were 1.15 and 5.0, respectively. This indicated that sediment dredging had great impacts on the water environment of Wulihu lake, including sediment re-suspension, water transparency decrease, release of the internal nutrients and heavy metal ions etc. In this paper, the risk of heavy metal release from re-suspended sediments and its certainty level were assessed and forecasted with the equilibrium partitioning model and the Monte Carlo romantic sampling method. The results also suggested that during sediment dredging, most of heavy metal ions have a great risk of release from re-suspended sediments with the certainty level over 90%; especially for Ni2+ and As, the release levels of which were 28.6％～∝of EQS and 34％～∝ of EQS, respectively. Thus, sediment dredging would cause a risk of water quality deterioration in Wulihu lake. Others, the application of Monte Carlo sampling model may offer a new tool to assess a potential risk of deteriorations in water environment with sediments dredging. |
