单体稳定碳同位素分析多氯联苯和多溴联苯醚的转化机理

Polychlorinated biphenyls (PCBs) and polybrominated diphenyl ethers (PBDEs) are two kinds of highly concerned organic pollutants, which have complex transformation processes in the environment. However, there are large gaps in our understanding on the transformation mechanism of these pollutants. Compound-specific stable isotope analysis (CSIA) is a new analytical technology developed in the last 20 years which has been applied mainly to degradation and source identification of organic pollutants in the environment. Therefore, we attempt to investigate the different transformation processes, including photodegradation and biotransformation of PCBs and PBDEs based on laboratory experiments. The alternations in contaminant’s congener profiles and the stable carbon isotope compositions of individual PBDE/PCB congener will be determined in both photodegradation and vitro hepatic biotransformation. The variations of stable carbon isotope composition of the target compounds will be assessed to explore the nature functional mechanisms of different metabolic processes. Our specific objectives are to develop a method to characterise the different transformation processes of PCBs and PBDEs by CSIA. This project will improve the understanding on the different transformation mechanisms of PCBs and PBDEs and play a substantially important role in evaluating the environmental risk of these pollutants correctly.

多氯联苯（PCBs）和多溴联苯醚（PBDEs）等持久性有机污染物在环境中具有复杂的转化过程，但目前对其不同转化过程的机理研究十分缺乏。单体稳定同位素分析（CSIA）是近二十年发展起来的一项新技术，在环境科学领域广泛应用于有机污染物的源解析及转化过程的示踪。本研究拟以PCBs和PBDEs为目标化合物，通过实验室内模拟目标化合物的光降解和生物转化过程，结合单体稳定碳同位素组成分析和污染物的定性定量分析，了解单体稳定碳同位素组成变化与目标化合物不同作用机制的内在联系，探讨应用CSIA技术分析目标化合物不同转化过程的可能。本项目的完成，对于认识PCBs和PBDEs不同转化过程的作用机理、科学评价PCBs和PBDEs的环境暴露风险具有重要意义。

持久性有机污染物在环境中存在复杂的降解转化过程，包括光降解和生物转化。因此进行持久性污染物的不同转化过程的研究对于客观评价该类型污染的环境行为和归宿具有重要意义。本项目针对典型的持久性有机污染物-多溴联苯醚进行光降解和生物代谢过程的研究并应用单体稳定同位素技术进行不同转化过程中目标物单体稳定碳同位素组成的分析，结合定性定量数据，深入讨论目标物不同转化过程的差异性、调控机制及转化机理。研究表明多溴联苯醚存在显著的物种差异性代谢，主要是由于生物体不同亚型脱碘酶活性差异造成；光降解过程中存在显著的同位素分馏效应而生物代谢过程其同位素比值变化不显著。研究结果对深入认识持久性有机污染物的不同转化过程的作用机理及科学评价其环境暴露风险具有重要意义。