底泥疏浚对五里湖沉积物生物毒性的影响

Effect of dredging on ecotoxicology of Wulihu lake sediments

为评价疏浚对太湖五里湖沉积物毒性的影响,采用淡水沉积物重金属质量基准和发光细菌试验法对疏浚前后太湖五里湖沉积物的生态毒性风险进行了分析。结果显示,疏浚后,尽管沉积物中Cu和Zn的总体含量降低至毒性效应低值(TEL/TEC)以下,Cr、Pb和Ni等重金属的总体含量降低至毒性效应最高值(PEL/PEC)以下,但沉积物提取液对发光菌的毒性却显著增加,且在疏浚后1个月时毒性最大,其EC25和EC50最小,分别仅为0.51%和9.16%。这表明,疏浚尽管可有效减少沉积物中重金属污染物总体含量,但并不能完全消除沉积物的生态毒性风险;相反,还有可能导致其生态毒性的风险性进一步增加。

To determine the effect of dredging on Wulihu lake ecosystem, the ecotoxicology risk of pre-and postdredging sediments were evaluated based on freshwater sediment quality guidelines and bioassay results. Dredging resuited in a significant reduction in the sediment＇s heavy metal contents concentrations of Cu and Zn were reduced to be low the respective TEL/TEC values and that concentrations of Cr, Pb and Ni were less than the PEL/PEC values, suggesting dredging would produce a substantial reduction in the sediment＇s ecotoxicity. However, the bioluminescence assay data for sediment elutriates （1 ： 1, w/w） showed higher bacterial toxicity immediately following the dredging; the observed 15 and 30 min EC25 were lower for three months, while the EC50 values were lower for more than seven months.