海洋绿藻对得克隆异构体生物富集的动力学机制研究

Dechlorane plus (DP) is chlorinated flame retardant which has been used at least 40 years and has high production volume now. The increase in DP use is expected because it was recently included in a European Commission report as a potential candidate to replace the now restricted decabromodiphenyl ether flame retardant. Its technical products consist of the syn and anti isomers in a ratio of about 1:3 to 2:3, but the ratio varied when DP entered the environment which indicated organism's bioaccumulation DP in isomer-specific manner. Although evidence showed its global occurrence and may be persistent, bioaccumulative and subject to long-range transport, more research is required to understand its ecological response and stereo-selective enrichment in marine environment, especially in intertidal area where easily influenced by human activates. Our previous research indicated that DP exposure inhibited the growth of macroalgae, and the fsyn value decreased in algae, showing that the syn-isomer is less bioaccumulative than that in anti-isomer. But the bioaccumulative process and its mechanism are behooved to know. In this project, Ulva pertusa, a worldwide marine green macroalgae was chosen to study 1) the process of stereo-selective enrichment in DP isomers by algae via laboratory exposure experiments and its bioaccumulative mechanism which can be analyzed by calculating and fitting with the two-phase model, in which the key bioaccumulation parameters such as uptake and deputation rate and half-lives in algae were expected to obtain; 2) the algal response with DP exposure by analyzing the changes of their photosynthesis, the oxidative damage and the cell membrane integrity to understand the eco-toxicological effects of DP in marine environment. It is expected to deeply understand the key questions of marine environmental fate and behaviors of DP, which may provide reference for future study on effects of similar marine organic contaminant.

人工合成的氯代阻燃剂得克隆（DP），是一种使用量大且在环境中广泛存在的新型有机污染物，具有顺、反两种异构体，在商品中以一定比例混合。在环境中两种异构体的比例发生了分异，被生物体选择性富集。但目前对于DP选择性富集的过程和机制还不清楚，DP在海洋环境所引发的生态效应研究还很匮乏。在前期工作中，我们发现DP可抑制藻类的生长并选择性的富集反式DP。本项目拟在前期工作的基础上，选择广泛分布的潮间带绿藻孔石莼作为模式材料，利用毒物代谢动力学方法研究孔石莼对DP异构体的选择性生物富集过程；通过数学模型对生物富集机制进行分析；同时从光合生理、氧化应激和细胞膜完整性等角度探讨DP富集所引起的生物学效应，确定DP的毒性剂量阈值，进而剖析DP对潮间带区域的生态毒理学效应。本项目的实施将有助于明确DP在海洋生态系统中选择性富集的关键问题，为今后开展其它有机污染物对海洋生态环境影响的相关研究提供参考。

近年来氯代阻燃剂得克隆（DP）的选择性生物富集及毒性效应研究得到了广泛关注。本项目以海洋绿藻孔石莼为研究对象，通过室内静态暴露实验，分别对孔石莼成体及幼体对DP的吸收、清除动力学过程进行了分析；构建双箱数学模型获得了相关的动力学参数并在此基础上讨论了毒物剂量及发育阶段对DP异构体选择性生物富集的影响。同时从繁殖发育、个体生长、生理生化等层面研究了DP对孔石莼在个体、种群水平上的影响，并对DP对潮间带绿藻的生态风险进行了预测。结果表明，在1ug/L和100ug/L的暴露浓度下，孔石莼的成体和幼体均选择性富集anti-DP。而在低浓度暴露下（78ng/L）没有明显的选择性富集现象。发育阶段对孔石莼的选择性富集无明显影响，但二者的动力学参数存在差异。双箱模型在高浓度暴露下的拟合度高于低浓度暴露。10E-6 - 10E-8 mol/L DP暴露在多个层面引起了海藻的生物学效应。包括繁殖细胞转化及早期发育的抑制，光合效能的降低及氧化损伤等。虽然DP对海洋生物的急性毒性较低，仍可通过长期低剂量的暴露在个体、种群乃至群落水平产生影响。因此，DP的海洋生态毒性效应值得引起关注。