沱江沉积物中有机氯农药分布特征及其与藻类有机质的关系和生态风险评估

使用气相色谱-质谱联用仪分析了长江支流沱江流域48个表层沉积物中有机氯农药（organochlorine pesticides，OCPs）的残留水平，探讨了其分布和组成特征及其与总有机碳（total organic carbon，TOC）、藻类有机质之间的关系，以及评估其生态风险.结果表明沱江流域表层沉积物中OCPs的总含量为3.17~127 ng·g^-1，其中六六六（hexachlorocyclohexane，HCHs）类农药的含量为2.83~86.0 ng·g^-1，滴滴涕（dichlorodiphenyltrichloroethane，DDTs）类农药的含量为0.340~40.9 ng·g^-1.OCPs空间分布特点为：上游 < 中游 < 下游 < 支流.HCHs和DDTs的组成成分分析表明，沱江流域存在林丹输入的现象，主要来自于历史残留，这与绝大多数流域的DDTs的输入状况相似.OCPs含量与TOC、藻类有机质含量之间存在着极显著的正相关性关系，表明藻类有机质在TOC对沉积物中的OCPs分配中起更为重要的作用.生态风险评估表明，沱江流域表层沉积物的有机氯农药存在较大的生态风险，可能对河流的底栖生物及生态环境造成明显的影响.

Distribution characteristics of organochlorine pesticides in sediments of the Tuojiang River and its relationship with algae-derived organic matter and ecological risk assessment

Gas chromatography mass spectrometry (GC-MS) was used to analyze the residual levels of organochlorine pesticides (OCPs) in the surface sediments at 48 sampling points in the Tuojiang River, a tributary of the Yangtze River. The distribution and composition characteristics of OCPs, and its relationship with total organic carbon (TOC) and algae-derived organic matter were discussed. The ecological risks of OCPs were evaluated as well. The results showed that the total contents of OCPs in the sediments ranged from 3.17 to 127 ng·g^-1, among which the contents of hexachlorocyclohexane (HCHs) ranged from 2.83 to 86.0 ng·g^-1, and the contents of dichlorodiphenyltrichloroethane (DDTs) ranged from 0.340 to 40.9 ng·g^-1. Its spatial distribution could be rearranged in the sequence: upstream < midstream < downstream < substream. The analysis of the composition of HCHs and DDTs showed that there was lindane input in the Tuojiang River recently, and most of the DDTs in the river mainly originated from historical residues. It was found that the TOC contents and algae-derived organic matter contents were highly significant and positively correlated with HCHs and DDTs contents, respectively, indicating that the algae-derived organic matter importantly contributed the TOC contents, and played a critical role in distribution of OCPs in the sediments. Ecological risk assessment showed that HCHs and DDTs in the surface sediments gave high ecological risks to the Tuojiang River, suggesting that they may have a significant impact on the benthic organisms and the ecological environment.