我国大闸蟹中二噁英类持久性有机污染物的暴露水平研究

目的研究我国大闸蟹中二噁英类持久性有机污染物(persistent organic pollutants,POPs)的暴露水平,评估大闸蟹中二噁英类POPs的主要污染来源。方法样品经正己烷和二氯甲烷(1:1,V:V)提取,浓硫酸沉淀脂类杂质后,过复合硅胶柱和碱性氧化铝柱净化分离目标物。采用同位素稀释高分辨气相色谱-高分辨质谱法(isotope dilution high resolution gas chromatograph-high resolution mass spectrometer,isotope dilution HRGC-HRMS)分析大闸蟹及其食物源中二噁英和多氯联苯的含量。结果蟹肉中二噁英类POPs的总毒性当量(toxic equivalent,TEQ)为0.0092～1.65 pg TEQ/g,平均浓度为0.27 pg TEQ/g。蟹黄(蟹膏)中二噁英类POPs的TEQ浓度水平为1.3～15 pg TEQ/g,平均浓度是蟹肉中平均TEQ值的21倍。估算一亩蟹塘中的物料平衡,发现饲料中二噁英类POPs的TEQ值是大闸蟹的0.85倍,玉米、水草和水仅贡献蟹塘中TEQ输入的4.7%,不考虑生物过程,沉积物中TEQ输入是饲料输入的77倍。结论蟹塘中二噁英类POPs的TEQ输入量高于其输出量,其中沉积物是大闸蟹中二噁英类POPs的主要贡献者,定期清理和更换养殖蟹塘中的沉积物可有效减少大闸蟹对二噁英类POPs的暴露。

Study on exposure levels of dioxin-like persistent organic pollutants in Chinese hairy crabs

Objective To investigate the exposure levels of dioxin-like persistent organic pollutants (POPs) in Chinese mitten crabs and assessed the main pollution sources of dioxin-like POPs in crabs. Methods The samples were extracted with n-hexane and dichloromethane (1:1, V:V). After the lipid impurities were precipitated by concentrated sulfuric acid, the target was purified by a composite silica gel column and a basic alumina column. Polychlorinated dibenzo-p-dioxins content and dibenzofurans and polychlorinated biphenyls content in crabs and food sources were analyzed by isotope dilution high resolution gas chromatography-high resolution mass spectrometry (isotope dilution HRGC-HRMS). Results The total toxic equivalents (TEQ) of dioxin-like POPs in crab meat were 0.0092-1.65 pg TEQ/g, and the average concentrations were 0.27 pg TEQ/g. The TEQ concentrations of dioxin-like POPs in crab yellow (crab cream) were 1.3-15 pg TEQ/g, and the average concentration was 21 times the average TEQ value in crab meat. Estimating the material balance in an acre crab pond, it was found that the TEQ value of dioxin-like POPs in the feed was 0.85 times that of the hairy crab, and corn, water grass and water contributed only 4.7% of the TEQ input in the crab pond. Regardless of the biological process, the TEQ input in the sediment was 77 times that of the feed input. Conclusion The TEQ inputs of dioxin-like POPs in crab pond are much higher than the outputs. Sediment is the main contributor to the dioxin-like POPs in crabs. Cleaning and replacement of sediments in crab ponds regularly can effectively reduce the exposure of dioxin-like POPs to crabs.