南方14种污泥中六溴环十二烷的浓度水平与组成特征

摘要

六溴环十二烷（Hexabromocyclododecane，HBCD）具有环境持久性、生物富集和潜在毒性，目前已被斯德哥尔摩公约组织列入“持久性有机污染物”禁用清单中。通过采集珠江三角洲地区14家污水厂的污泥样品，利用液相-双质谱研究了该区域污泥中HBCD的污染水平和异构体组成特征。研究结果表明，珠江三角洲地区污泥中HBCD的平均质量分数为8.4 ng·g-1干重，质量分数范围在1.1~29.3 ng·g-1干重之间，且其含量水平与污水厂的处理工艺、污泥的总有机质含量等无显著相关性；与国内外其它研究区域相比，珠江三角洲地区污泥中 HBCD 的含量水平与上海、北京等其他典型城市相当，但显著低于爱尔兰、荷兰、英国等欧洲地区；不同厂家的污泥中HBCD的异构体组成模式各不相同。总共14个污泥样品中，有13个样品的HBCD异构体组成与商用技术产品有显著差异，其分布模式与珠江三角洲地区其他环境介质的研究结果较为一致，表明了环境样品中 HBCD 的异构体组成已经发生改变。结合珠江三角洲地区其他环境介质的研究结果，推断研究区域内污泥中 HBCD 异构体组成模式的变化主要来源于光降解和热转化等非生物转化过程，但仍需通过深入开展模拟实验来进一步验证。%Due to their environmental persistence, bioaccumulation, and potential toxicity, hexabromocyclododecane (HBCD) has been placed into the list of prohibited chemicals by the Stockholm Convention. Therefore, it has been drawn high attention of scientists recently. In this study, fourteen sludge samples were collected from the wastewater treatment plants in regions of the Pearl River Delta. The concentration levels and composition profiles of HBCD in the sludges were investigated using liquid chromatography coupled to tandem mass spectrometry. The results indicated that, the mean concentration of HBCD was 8.4 ng·g-1 dry weight, ranging from 1.1 to 29.3 ng·g-1 dry weight. There is no statistical correlation between the HBCD concentrations and total organic contents of sludges. Compared with other reported data, the concentrations of HBCD in this study were similar to those in the sludges from Beijing and Shanghai cities, whereas is significantly lower than those in Europe countries such as Ireland, Netherland, and England. The compositional profiles of HBCD in this study exhibited various characteristic. And most of them were significantly different with those in commercial technical products; however, they were similar to those observed in other environmental media (such as air and soil) in the Pearl River Delta. This phenomenon showed that the compositional profiles of HBCD in the sludges have been changed in the environmental process. Combined with other environmental HBCD observations in the Pearl River Delta, we suggested that abiotic transformation such as thermal process and photo degradation might be the major reasons for the transformation of compositional profiles.