巢湖表层水体中DDTs农药的残留特征、来源解析与风险评价

摘要

2009年8月采集了巢湖河流及湖泊表层水体共15个样点,利用固相萃取-气相色谱-电子捕获检测器(SPE-GC-ECD)方法测定滴滴涕类(DDTs)农药的含量,分析了其残留特征、来源及风险.结果表明:1)巢湖丰水期DDTs含量范围为1.52-21.79ng/L,平均含量为9.98±4.73ng/L.2)DDT残留主要来自历史上工业DDTs农药的残留和其他o,p'-DDT/P,p'-DDT值较高的农药(如三氯杀螨醇)的使用,东部水源区主要是厌氧条件.3)物种敏感性分布评估模型(SSD)得到的全部物种的风险为8.3×10-15-2.1 ×10-8,各样点生态风险很小;DDT对所有物种、脊椎动物、无脊椎动物、鱼类、甲壳类和昆虫与蜘蛛的安全阈值分别为1.51、1.91、1.26、0.83、1.70和1.51;5%的水生生物物种受到影响时DDT超过毒性值的风险概率为24.5%,对脊椎动物、无脊椎动物、鱼类、甲壳类和昆虫与蜘蛛类的风险概率分别为15.6%、31.9%、17.5%、46.9%和18.7%.三种风险评价方式得到一致的结果,即巢湖DDT对无脊椎动物(如甲壳类)的生态风险大,而对脊椎动物(如鱼类)的生态风险小.4)用巢湖水饮用或者洗浴时,DDTs致癌风险均在百万分之一以下,风险很小;非致癌风险值均远远小于1,不会对人体产生明显非致癌健康危害.%The contents of dichloro diphenyl trichloroethanes (DDTs) in surface water from fifteen sampling sites in Lake Chaohu were measured by solid phase extraction-gas chromatograph-electron capture detector (SPE-GC-ECD).The DDTs residues, possible sources, as well as potential ecological and health risks were analyzed.The following results were obtained: 1 ) the average content in the lake water was 9.98 ± 4.73 ng/L, with the range of 1.52 -21.79 ng/L.2) The sources of DDT were mainly from historical usage of technical DDTs pesticides and recent usage of other pesticides with larger ratio of o,p’-DDT to p,p’-DDT ( such as dicofol).The eastern water source area was mainly under anaerobic conditions.3 ) The water ecological risk to all species at various sample sites by Species sensitivity distribution (SSD) model was very low with the range of 8.3 × 10 - 15-2.1 × 10 -8.Margin of safety (MOS10) of DDT for all species, vertebrates, invertebrates, fish, crustaceans and insects & spiders were 1.51,1.91,1.26,0.83,1.70, and 1.51.In case of 5％ freshwater organisms affected, the risk probability of DDT exceeding HC5 for all the species, vertebrates, invertebrates, fish, crustaceans, and insects & spiders was 24.5％ , 15.6％ , 31.9％ , 17.5％ ,46.9％ and 18.7％ , respectively.The risk assessment results by three methods were with good agreement, showing that the ecological risk of DDT to invertebrates ( e.g.crustaceans) was higher than that to vertebrates ( e.g.fish), and that the DDT ecological risk was very low in Lake Chaohu.4) DDTs' carcinogenic risk was lower than 10 -6, and its non-carcinogenic risk was far less than 1, implying that it would not cause significant carcinogenic and non-carcinogenic human health risk when using the lake water as drinking and bathing.