府河和白洋淀沉积物中DDTs的分布特征和风险评估

Characteristics of Distribution and Risk Assessment of DDTs in Surface Sediments from Fuhe River and Baiyangdian Lake

利用气相色谱-质谱（GC-MS）检测了府河和白洋淀共计19个表层沉积物样品中的W（DDTs）及其分布特征．结果表明，W（DDTs）为1．74～51．33ng／g（以干质量计），平均值为11．01ng／g，其分布特征呈现从府河到白洋淀逐渐递减的趋势．与国内其他地区沉积物相比，府河和白洋淀地区DDTs的污染处于中等偏低的水平．在所有沉积物样品中，P，P′-DDT所占比例较大，是最主要的异构体．大部分样品中W（DDD）／w（DDE）大于1，而W（DDT）／W（DDE＋DDD）小于1，说明研究区DDT处于厌氧环境条件，且没有新的DDT输入．该地区DDTs主要来源于农田土壤侵蚀及工业废水排放．潜在风险评估表明，府河和白洋淀的表层沉积物中DDTs对周围环境具有一定的影响，应引起相关部门的重视．

Nineteen surface sediment samples collected from Fuhe River and Baiyangdian Lake were analyzed for DDTs using gas chromatography coupled to a mass spectrometer （GC-MS）. The total concentrations of DDTs ranged from 1.74 to 51.33 ng/g dry weight （11.01 ng/g on average）, with a decreasing trend from the Fuhe River to Baiyangdian Lake. The DDTs concentrations were moderate or relatively low compared to data from other areas of China. Among DDTs isomers, p, P′-DDT was the predominant isomer for all the sediment samples. The ratios of DDD/DDE were higher than 1 for most sediment samples, indicating the degradation of DDT under anaerobic conditions. The ratios of DDT/（DDE ＋ DDD） were lower than 1 for all the samples, showing that there possibly were no new inputs of DDTs. The main sources of DDTs were long-term weathering of soil and discharge of industrial sewage in the study area. Risk assessment indicated that DDTs in the sediments from the Fuhe River and Baiyangdian Lake were most likely to pose impairment to the biota in the study areas to some extent.