沁河沿线有机氯农药的分布特征及风险评价

Distribution of Organochlorine Pesticides along the Qinhe River and Its Risk Evaluation

为了解沁河有机氯农药(OCPs)的残留状况,利用气象色谱仪测定了沁河干流沿线水体和表层沉积物中六六六(HCHs)和滴滴涕(DDTs)的含量,并分析了其来源.结果表明,沁河水体和表层沉积物中大部分样点均检出有机氯农药的残留,其中水体中HCHs和DDTs含量分别为nd-2.23 ng/L和nd-19.35 ng/L;表层沉积物中HCHs和DDTs含量分别为nd-13.72 ng/g和nd-14.02 ng/g.对组成特征的分析表明,沁河沿线中游没有新的商品HCHs的输入,而下游存在一定林丹的使用;沁河中下游有新的DDTs的输入,其主要来源是三氯杀螨醇和历史残留.与国内其他主要河流相比,沁河沿线水体和表层沉积物中有机氯农药的含量处于中等水平.根据淡水生态系统风险评估值进行比较,沁河沿线表层沉积物中有机氯农药的生态风险较低.

To determine the residues of organochlorine pesticides （OCPs） of the Qinhe River, the authors measured the contents of hexachlorocyclohexanes （HCHs） and dichlorodiphenyltrichloro-ethanes （DDTs） in the main stream and surface sediments along the Qinhe River using the gas chromatography-electron capture detection （GC-ECD）, and analyzed its composition and sources. The results showed that most sampling sites had organochlorine pesticide residues in the main stream and surface sediments of the Qinhe River. The total concentrations of HCHs were in the range of nd-2.23 ng/L, and DDTs of nd- 19.35 ng/L in the water samples; the total HCHs ranged from nd-13.72 ng/g and the total DDTs from nd-14.02 ng/g in surface sediments. Composition characteristics revealed no new input of commodity HCHs in the midstream of the Qinhe River, where Lindane existed. There were new inputs of DDTs near the middle and lower reaches of the Qinhe River, mainly from dicofol and historical residues. Compared with other major rivers in China, the content of organochlorine pesticides in water and surface sediments in the Qinhe River is at the middle level. According to the ERL and ERM value of risk evaluation for freshwater ecosystems which can also be applied for river, sediments in the Qinhe River pose a low risk to the environment. Fig 5, Tab 4, Ref30