长三角地区饮用水源地沉积物中有机氯农药污染特征

Characteristics of organochlorine pesticides in the sediments from the drinking water source of the Yangtze River delta region

2015年4月采集长江三角洲地区河流型、河网型和湖泊型饮用水源地沉积物,采用同位素稀释高分辨气相色谱-高分辨质谱法测定了22种有机氯农药(OCPs).结果表明,采集的沉积物中测定的22种有机氯农药都有检出,滴滴涕(DDTs)、六氯苯、六六六(BHCs)、五氯苯的检出率为100%;有机氯污染水平依次为:嘉兴河网(浓度范围为1.71—61 ng·g^(-1),中值为12.4 ng·g^(-1))>长江下游(浓度范围为0.46—93 ng·g^(-1),中值为8.59 ng·g^(-1))≈钱塘江(浓度范围为1.02—69 ng·g^(-1),中值为8.1 ng·g^(-1))>太湖(浓度范围为1.76—8.65 ng·g^(-1),中值为3.53 ng·g^(-1)).DDT及其降解产物的浓度与其他地区的含量相当.依据DDTs和BHCs的同分异构体比值的变化和主成分分析结果对污染源进行解析,结果表明嘉兴河网主要以氯丹、九氯和六六六为主要污染特征,该地区有氯丹的使用和六六六的历史残留.钱塘江主要以BHCs、氯丹和DDTs为主要污染特征,有林丹的输入.太湖主要污染特征为DDTs和BHCs,并有新源输入.长江下游主要以o,p'-DDT和BHCs为污染特征,有些采样点表明有三氯杀螨醇的使用,六六六为历史残留.对长三角地区水源地沉积物进行生态评价发现,滴滴涕类有机氯农药存在潜在生态风险,其中DDTs具有潜在生态风险的采样点占74%,具有生态风险的采样点占2%.

Concentrations of 22 organochlorine pesticides（ OCPs） were analyzed in sediments collected from drinking water source of the Yangtze River Delta region with isotope dilution HRGC /HRMS. The results showed that all of the 22 organochlorine pesticides were detected,and DDTs,hexachlorobenzene,BHCs and pentachlorobenzene were detected in all samples. The concentrations of OCPs descended in the order： Jiaxing river network（ ranged from 1. 71 to 61 ng·g^（-1）,median：12.4 ng·g^（-1）） the Yangtze River（ ranged from 0. 46 to 93 ng·g^（-1）,median： 8. 59 ng·g^（-1））,Qiantang River（ ranged from 1.02 to 69 ng·g^（-1）,median： 8.1 ng·g^（-1）） Taihu（ ranged from 1.76 to8.65 ng·g^（-1）,median： 3.53 ng·g^（-1））. The concentration of DDT and its degradation products were comparable with other areas. The sources of OCPs were drawn by principal component analysis and compositional pattern of DDTs, BHCs and chlordane. The dominant OCPs were chlordane,nonachlor and BHCs in sediments from drinking water sources of Jiaxing river network,suggesting that illegal use of chlordane,and BHCs residue in this region. In drinking water sources of Qiantang River,the dominant OCPs were chlordane,nonachlor and BHCs,and there was fresh γ-BHC input in this region. The dominant OCPs were DDTs and BHCs in sediments from drinking water sources of Taihu,and there were fresh DDTs and BHCs input. In drinking water sources of the Yangtze River,the dominant OCPs were o,p＇-DDT and HCHs,indicative of a possible new input from the DDT impurity in dicofo and residue of BHCs. The environmental risk assessment results indicated DDTs in sediments pose potential ecological risk to consumers of bottom feeders, DDTs pose potential ecological risk in 74% of the sampling sites,and ecological risk in 2% of the sampling sites.