六溴环十二烷对映体在蚯蚓体内的选择性富集、代谢行为研究

Hexabromocyclododecanes （HBCDs），an additive brominated flame retardant(BFRs)，are listed as a candidate for the Stockholm Convention on Persistent Organic Pollutants (POPs) because of their persistency, bioaccumulation, longrange transport, and toxicity. Currently, the study on diastereoismer- and enantiomer of HBCDs mainly focused on the selective enrichment and pollution characteristics in soil, sediment, fish, and birds. Diastereoismer- and enantiomer-specific enrichment and metabolic processes of HBCDs are still the lack of enough understanding in the soil animal. The analysis methods of diastereoismer and enantiomer of HBCDs in earthworm would be developed based on the LC-MS/MS with chiral stationary phase. Earthworms were exposed to the two concentions of individual HBCD diastereoisomer (α-,β-,γ-HBCD), to determine diasteroisomer- and enantiomer- spectific residue levels, possible degradation products and to examine the selective accumulation, degradation, and chiral signatures in earthworms. The degradation kinetics, transformation mechanism, and degradation pathway would be clarified in earthworm. Meanwile, the reasons of selective degradation and transformation would be discussed in vitro in earthworm microsomes. There would be important significance for further understanding of the environmental fate and risk of the HBCDs. These scientific achievements would have provided the scientific data for the application of HBCDs ecological health risk assessment and phytoremediation.

添加型溴系阻燃剂六溴环十二烷（HBCDs）因其"持久性、蓄积性、迁移性和毒性"被斯得哥尔摩公约列为受审物质。目前，对手性HBCDs的研究主要集中在土壤、沉积物、鱼类、鸟类等异构体及其对映体污染特征以及选择性累积的检测上，而对其在土壤动物体内的富集、代谢等过程尚缺乏足够的认识。本项目以土壤动物蚯蚓为试验对象，利用手性分离技术和蚯蚓暴露模拟的试验方法，建立蚯蚓体内HBCDs异构体及其对映体的残留分析方法，通过对HBCDs异构体及其对映体在蚯蚓体内残留水平、对映体组成及可能代谢产物的检测，研究其选择性富集、转化、代谢过程，揭示HBCDs异构体及其对映体在蚯蚓体内的转化规律和代谢途径，阐明其选择性富集、代谢机理。同时通过蚯蚓微粒体体外孵育实验，探讨发生选择性代谢、转化的原因。本项目的完成对于进一步认识HBCDs的环境行为及风险性具有重要意义，为正确评价其生态健康风险以及环境污染治理修复提供科学。

六溴环十二烷（Hexabromocyclododecanes（HBCDs））是一种全球添加的溴系阻燃剂，具有环境持久性、长距离迁移性、生物富集性及毒性，危害着生态环境和人类健康，引起了国内外学者的广泛关注。目前，对手性HBCDs的研究主要集中在土壤、沉积物、鱼类、鸟类等异构体及其对映体污染特征以及选择性累积的检测上，而对其在土壤动物体内的富集、代谢等过程尚缺乏足够的认识。本项目以蚯蚓为模式生物，开展了三个层次的研究工作，一是建立了手性HBCDs异构体在土壤和蚯蚓体内高效液相色谱-同位素稀释串联质谱分析方法；二是开展了HBCDs三个异构体在赤子爱胜蚓体内的累积和代谢过程，重点阐述了蚯蚓对HBCDs对映体的富集、代谢规律；三是探讨了蚯蚓微粒体对HBCDs降解的催化作用。结果发现：三种异构体的生物富集系数（BAF）是α-HBCD>γ-HBCD >β-HBCD，但α-HBCD的半衰期（t1/2）比β-和γ-HBCD长，这些结果说明了HBCDs在生物体内的累积具有异构体选择性，同时也对三对对映体研究发现，赤子爱胜蚓选择性累积（-）-α-HBCD、（-）-β-HBCD和（-）-γ-HBCD比（+）-α-HBCD、（+）-β-HBCD和（+）-γ-HBCD。研究还发现赤子爱胜蚓能将β-和γ-HBCD生物异构化为α-HBCD，同时在其体内检出了代谢产物Hydroxy-TBCDs、PBCDs，dihydroxy-HBCDs等。