水环境中含氯有机磷酸脂的生物转化与累积特征研究

Organophosphate esters (OPEs), as the replacements for traditional brominated flame retardants, their output and consumption are increasing year by year. Previous research showed that they have been widespread in water environment, and they might have neurotoxicity, reproductive toxicity, etc. Thus, they might pose potential ecological risk. However, their biotransformation and bioaccumulation mechanism are still unclear. In order to evaluate the ecological risk of OPEs scientifically, the project intends to carry out their toxicity mechanism research in aquatic organisms. The chlorinated OPEs, which have high contents and are more persistent in water environment, are selected as the research object. Throughout the whole project, the indoor simulation, exposure experiment and field investigation would be combined using the high precision UPLC-MS/MS analysis, fluorescence quantitative PCR, proteomics technology, etc. Finally, the biotransformation and bioaccumulation process of several chlorinated OPEs would be revealed. The juvenile rainbow trout would be used as a fish model in laboratory simulation exposure experiment, and the metabolic metabolism of several chlorinated OPEs in rainbow trout would be elaborated. Meanwhile, the different biological indicators and the possible metabolites would also be analyzed to explore the biomarker. By means of field investigation method, the content distribution characteristics of OPEs in different trophic level organisms and the bioaccumulation characteristics would be illuminated. The results of the present project will provide the scientific basis for the risk assessment and environment supervision of emerging organophosphate flame retardants.

有机磷酸酯作为传统溴代阻燃剂的替代品，其产量和使用量逐年增加。已有研究表明：其在水环境介质中已广泛存在，而且具有神经、生殖等多种毒性，存在生态风险。但是，目前其生物转化机制与累积特征仍不清楚。为了更科学地评价有机磷酸酯的生态风险，项目拟开展其在水生生物中的毒性机理研究。选择我国典型湖泊中含量较高、且持久性较强的含氯有机磷酸酯为研究对象，采用室内模拟、暴露实验与野外调查相结合的方式，运用高精度液相色谱串联质谱、荧光定量PCR、蛋白质组学等技术，揭示水环境中几种含氯有机磷酸酯的生物转化和累积过程。室内模拟暴露实验以虹鳟幼鱼为模式生物，阐述含氯有机磷酸酯在虹鳟体内的代谢转化机理，分析不同生物指标的变化和代谢产物，探明其生物标志物。野外研究不同营养级生物中有机磷酸酯的含量分布，揭示其生物累积特征。研究成果可以为新型有机磷阻燃剂的风险评估和环境监管提供依据。

有机磷阻燃剂是一种以物理方式添加于材料的新型阻燃剂，被广泛用于家具、纺织品和电子产品等多种产品中。近些年有机磷酸酯（OPEs）作为有机磷阻燃剂的主要化学品，在阻燃剂市场上应用广泛，环境中的检出量也越来越高，对生物的毒性和生态风险逐渐显露出来。然而，关于OPEs对生物的毒性作用机制和生物转化行为等尚不明确。本项目选取3种OPEs作为目标污染物，开展对水生生物的毒性效应机理和生物转化行为研究。主要研究成果如下：1)系统分析了OPEs的毒性效应机制，构建了其在水生生物（斑马鱼、稀有鮈鲫和日本青鳉鱼）中引起的不同毒性效应的有害结局路径框架。通过分子起始事件、关键事件和有害结局，AOP可很好地将现有的OPEs毒性效应机制和毒性终点有机串联起来，也为后续OPEs的健康危害和生态风险评价提供理论基础；2)选取一种典型的OPEs，在鲫鱼肝微粒体中开展体外代谢动力学实验,结果发现其代谢动力学过程符合Michaelis-Menten模型，由此计算出对应的代谢速率Vmax 为12700 ± 2120 pmol/min/mg protein，体外肝清除率CLint 为12.3 μL/min/mg protein，Michaelis-Menten常数Km 为1030 ± 212 μmol/L。CDP与同为芳香基的磷酸三苯酯的Vmax和CLint值均大于烷基和氯代OPEs，这可能与芳香基OPEs较高的logKow和生物富集系数相关；3）对斑马鱼进行28d暴露后进行生物学指标分析和分子对接模拟实验，结果发现：OPEs可与甲状腺素结合球蛋白和转甲状腺素蛋白结合后在体内运输，并在TTR的作用下，将OPEs运输到大脑，从而引起甲状腺激素受体结合过程、甲状腺发育过程、甲状腺激素跨膜运输活性、细胞分化、神经配体-受体相互作用和MAPK信号通路等多个信号通路紊乱，最终抑制斑马鱼的生长发育。本项目的研究成果可以为这类新型有机磷阻燃剂的水质基准标准制修订、生态风险评估和环境监管提供依据。