海洋发泡聚苯乙烯微塑料中六溴环十二烷的释放及生物富集

Marine microplastic pollution, as an important environmental problem, has rapidly caught much attention in recent years. Given the inadequate studies on the release and bioaccumulation of additive flame retardants, expanded polystyrene (EPS), which is widespread in seawater, and a brominated flame retardant, hexabromocyclododecane (HBCD), which is its characteristic flame retardant in EPS, are chosen to be the targets in this project. The release kinetics of EPS in seawater will be studied by combining water passive sampling with the liquid-liquid extraction, and the long-term release potential of HBCD in seawater will be revealed. Meanwhile release dynamics of HBCD in the simulated digestive juice will be explored, and a key scientific issue on EPS function as the source or sink of HBCD will be answered. By combination of settlement panels and depuration tests, the potential of EPS microplastics as a source and carrier of HBCD in marine ecosystem will be confirmed by field evidence. Using stable isotopic abundance of carbon and nitrogen, effect of selective bioaccumulation of HBCD isomers on marine organisms at different trophic levels will be elucidated. Upon completion, the project will be helpful for a better understanding of biogeochemical cycles of HBCD released from EPS marine microplastics, and is expected to provide a scientific basis for the accurate assessment of HBCD to marine environmental health and ecological risks.

海洋微塑料污染作为一个重要环境问题近年来迅速成为全球关注热点。针对微塑料中添加型阻燃剂的释放及生物富集方面的研究不足，本项目选择海水环境中广泛分布的发泡聚苯乙烯(EPS)微塑料及其特征阻燃剂六溴环十二烷(HBCD)为研究对象，通过水体被动采样结合液液萃取技术研究EPS微塑料中HBCD的海水释放动力学，揭示其在海水中长期释放HBCD的潜力；同时利用模拟消化液研究EPS微塑料中HBCD的体内释放动力学，解答EPS微塑料在消化液中是HBCD“源”还是“汇”的关键科学问题；再通过野外挂板和生物体清肠实验，用野外证据进一步判断EPS微塑料是否充当海洋生态系统中HBCD的污染源和载体；结合稳定碳氮同位素技术，阐明EPS微塑料对不同营养级生物选择性富集HBCD异构体的影响。项目研究将有助于增进对EPS微塑料中HBCD生物地球化学过程的认识，为准确评估HBCD对海洋环境健康和生态风险提供科学依据。

微塑料是一种全球广泛分布的新兴污染物，其污染问题越来越受到人们的高度关注。然而，关于微塑料中添加剂的释放及生物富集的研究仍存在大量空白。为此本项目选择海洋环境中分布广泛的发泡聚苯乙烯（EPS）微塑料及其添加型阻燃剂六溴环十二烷（HBCD）为研究对象，探究了微塑料中添加型阻燃剂的释放及生物富集。通过一系列的室内实验阐明了EPS微塑料中HBCD的释放动力学，并考察了影响HBCD释放过程的几种参数。结合野外实验研究了EPS浮标与阻燃剂HBCD之间的源汇关系，探究了EPS微塑料对HBCD生物富集的影响。研究发现，EPS微塑料中HBCD的释放会受到EPS粒径、周围环境条件（温度、盐度和pH）、消化液中共存食物的影响。然而，消化液成分（如胃蛋白酶、胆汁盐）对EPS微塑料中HBCD的释放几乎没有影响。EPS微塑料中HBCD释放最主要的限速步骤是基质内部扩散，其次是塑料-环境介质界面扩散。研究还发现EPS微塑料既可以是HBCD的源，也可以是HBCD的汇。野外实验发现EPS浮标上的附着生物可以富集更多的HBCD，表明EPS浮标是水环境中HBCD重要的源。EPS浮标上HBCD可以通过水相暴露和食物相暴露两种途径进入生物体，也可以通过摄食EPS微塑料直接进入生物体。项目执行期间，正式发表学术论文24篇，培养博士后1名，研究生7名。项目研究结果有助于增进人们对塑料添加剂的生物地球化学循环过程的认识，为准确评估EPS微塑料的环境健康和生态风险提供科学依据。