太湖流域沉积物中有机氯农药空间分布特征及风险评价

Spatial Distribution and Risk Assessment of Organochlorine Pesticides in Surface Sediments of Taihu Lake Basin

为了解太湖流域表层沉积物中有机氯农药的空间分布和污染特征,采集全流域111个表层沉积物样品,用GC-μECD分析了20种有机氯农药的含量,并基于沉积物质量基准法对沉积物污染风险进行评价。结果表明:太湖流域沉积物中20种有机氯农药(OCPs)的总含量介于16. 3～96. 9 ng/g dw之间,平均值为35. 0ng/g dw,其中HCHs和DDTs是主要的检出成分,平均含量分别为12. 1、7. 6 ng/g dw,两者含量之和占总OCPs的25. 5%～85. 5%。特征化合物指数法分析结果表明,HCHs主要来源于林丹,而且该区域仍然有新的DDT输入,并且大部分p,p’-DDT通过好氧生物降解为p,p’-DDE。沉积物质量基准法评价结果显示,γ-HCH、DDTs潜在生物毒性较大。

Shallow lakes are important freshwater resources and have the functions of flood,transportation,agriculture,aquaculture,tourism,drinking and ecological protection. The environmental quality of shallow lakes is highly related to human health and sustainable development of social economy. Rapid urbanization and economic development have resulted,progressively,in deteriorating freshwater conditions. Lake Taihu is the third largest freshwater lake in China. In order to characterize the the pollution characteristics of organochlorine pesticides in surface sediments of Lake Taihu,32 and 79 sediment samples were collected in May 2013 from Lake Taihu and its tributary rivers,respectively. The contents of twenty organochlorine pesticides in the samples were analyzed by GC-μECD and the risk of sediment contamination was evaluated using sediment quality guidelines( SQGs). The results showed that OCPs were detected in all sediment samples,with residual values ranging from 16. 3 to 96. 9 ng/g dw,and the average content was 35. 0 ng/g dw. HCHs and DDTs were the major components,and the average contents were 12. 1 and 7. 6 ng/g dw,respectively. The content of HCHs and DDTs accounted for 25. 5% to 85. 5% of the total OCPs. The ratios of certain metabolites to their parent compounds indicated that the main source of HCHs was lindane,and lindane is still in use recently. There are still new inputs of parent DDT compound in Taihu Lake Basin,which might come from antifouling paints in fishing ships or other pesticides containing DDT,such as dicofol. A sediment risk assessment based on sediment quality guidelines( SQGs) suggested that γ-HCH and DDTs could be potential contaminants of greater ecotoxicological concern.