多溴联苯醚及其羟基和甲氧基衍生物在蚯蚓体内的富集和代谢反应研究

Polybrominated diphenyl ethers which have been detected in various environmental media are a kind of emerging persistent organic pollutants. They are prone to easily transform to more toxic hydroxylated PBDEs (OH-PBDEs) and methoxylated PBDEs (MeO-PBDEs) in environment. However, studies on the behaviors of PBDEs and their hydroxylated and methoxylated analogues in terrestrial environment are very limited, particularly regarding the enrichment and metabolism of PBDEs and their derivatives in the soil animal. In the present program, we select the earthworm as model organisms. Absorption and excretion dynamics experiments will be conducted to study the earthworm bioaccumulation of PBDEs, OH-PBDEs and MeO-PBDEs from soil. The metabolic reactions and mutual transformation relationship of PBDEs, OH-PBDEs and MeO-PBDEs in earthworm will be investigated through metabolic dynamics experiment. Ultimately, the molecular mechanism of metabolism of PBDEs, OH-PBDEs and MeO-PBDEs in earthworm will be revealed through the application of gene chip, homology modeling and molecular docking method. The aim of this study is to further reveal the environment interface behaviors of PBDEs in the terrestrial ecosystem, deepen understanding of their environmental health risks.

多溴联苯醚（PBDEs）是一类新型持久性有机污染物，已在多种环境介质中被检出。进入环境的PBDEs易发生转化产生毒性更强的羟基和甲氧基多溴联苯醚（OH-PBDEs和MeO-PBDEs）。目前有关PBDEs及其羟基和甲氧基衍生物在陆地生态系统中的环境行为的研究还非常有限，特别是有关PBDEs及其衍生物在土壤动物中富集和代谢转化的研究鲜有报道。本项目拟选择蚯蚓为模型生物，通过吸收、排泄和代谢动力学实验，应用基因芯片、同源建模和分子对接等手段：（1）研究土壤中PBDEs、OH-PBDEs和MeO-PBDEs的蚯蚓生物富集能力和规律；（2）研究三种污染物在蚯蚓体内发生的代谢反应和相互转化关系；（3）揭示PBDEs、OH-PBDEs和MeO-PBDEs在蚯蚓体内发生代谢转化的分子机制机理。本研究的目的是为进一步揭示PBDEs在陆地生态系统中的环境界面行为，加深对POPs的环境健康风险的认识。

本研究以赤子爱胜蚓为模式生物，BDE-47、6-OH-BDE-47和6-MeO-BDE-47为供试化合物，通过活体暴露试验研究了土壤-动物系统中PBDEs、OH-PBDEs和MeO-PBDEs的蚯蚓吸收、排出动力学过程，以及富集、转化特征，探讨了PBDEs及其羟基和甲氧基衍生物在蚯蚓体内的相互转化关系。研究结果表明：（1）土壤中的BDE-47、6-OH-BDE-47和6-MeO-BDE-47可以被蚯蚓快速吸收，且其吸收、排出动力学过程符合一级反应动力学。（2）蚯蚓对三种化合物的生物富集因子由高到低依次为：6-MeO-BDE-47> 6-OH-BDE-47>BDE-47。（3）在蚯蚓体内，三种化合物均可发生脱溴代谢，BDE-47和6-OH-BDE-47可以发生甲氧基化代谢生成MeO-PBDEs，且其甲氧基化代谢速率明显高于脱溴代谢速率。但是没有观察到OH/MeO-PBDEs向PBDEs转化。（4）6-OH-BDE-47在蚯蚓体内可以发生快速的甲氧基化代谢，且其代谢产物可以进一步发生脱溴反应。同时6-OH-BDE-47在蚯蚓体内可以发生脱溴和同分异构化代谢，然后氧化为MeO-PBDEs。本研究有助于全面认识土壤中PBDEs的迁移及最终归趋，为评估PBDEs的环境安全风险提供依据。