微塑料对全氟辛烷磺酸类物质在海洋双壳贝类体内生物富集和毒性效应的影响机制研究

The pollution of microplastics in marine environment received extensive attention in recent years. Due to their unique physiochemical properties different from large plastics, microplastics tend to combine with organic pollutants in water, which would alter the bioconcentration, bioavailability and toxicity of pollutants. Perfluorooctane sulphonate (PFOS) is a kind of emerging persistent organic pollutant, showing various toxic effects to aquatic organisms. In the present study, controlled experiments simulating marine ecological environment will be conducted with PFOS as the target pollutant. Fluorescently-labeled microscale and nanoscale polystyrene, polyethylene, polypropylene and polyvinyl chloride particles are obtained as representative microplastics. Filter feeding bivalve molluscs, including mussel and oyster, are ideal model organisms. The distribution of PFOS among the multi-phase system containing seawater, marine sediment, bivalves and microplastics will be investigated together with their interrelations, to reveal the mechanism for the effects of microplastics on the bioconcentration of PFOS in bivalves. The toxic effects of combined microplastics and PFOS will be evaluated through the measurement of toxicological endpoints including endocrine disruption and oxidative damage. Based on the analyses of DNA strand breaks and proteomics, the toxicological mechanisms for the combined toxic effects of microplastics and PFOS on bivalves will be explored on both cellular and molecular levels. The results would provide important scientific evidence for the water quality assessment and risk management of emerging pollutants in marine environment.

近年来，海洋环境中的微塑料污染受到广泛关注。不同于大型塑料的特殊理化性质使微塑料容易与水体中的有机污染物结合，改变污染物的生物富集量、生物可利用性和毒性效应。全氟辛烷磺酰类物质（PFOS）是一种新型持久性有机污染物，对水生生物具有多器官毒性。本研究以PFOS为目标污染物，以荧光标记的微米级和纳米级聚苯乙烯、聚乙烯、聚丙烯、聚氯乙烯颗粒为代表性微塑料，以滤食性双壳贝类贻贝和牡蛎为模式生物，通过模拟海洋生态环境的实验研究，揭示PFOS在海水-沉积物-贝类-微塑料多相体系中的分布规律和耦合关系，分析微塑料对PFOS在贝类体内生物富集的影响及机理。测定贝类体内雌激素效应和氧化损伤等毒理学指标，考察微塑料与PFOS复合污染对贝类的毒性效应。借助DNA损伤、蛋白质组学等分析手段，从细胞和分子水平上揭示微塑料与PFOS联合毒性效应的毒理学机制。研究结果可为海洋水质评价及新型污染物风险控制提供科学依据。

全氟及多氟烷基化合物（PFAS）是备受关注的新型有机污染物，海洋中的微塑料（MPs）污染及其生态效应是日益突出的环境问题，然而MPs如何影响PFAS类物质在水生生物特别是底栖双壳贝类体内的生物富集和毒性效应还缺乏系统的实验研究。本项目通过建立海水-全氟辛烷磺酸（PFOS）-MPs-翡翠贻贝（Perna viridis）水生态微域体系以及淡水- PFAS-MPs-河蚬（Corbicula fluminea）水生态微域体系，研究了聚苯乙烯（PS）、聚乙烯（PE）和聚氯乙烯（PVC）等不同类型的微塑料对PFOS及其替代品铬雾抑制剂氯代多氟烷基醚磺酸盐（F-53B）在底栖双壳贝类体内生物富集的影响，并多角度揭示了微塑料与PFAS复合污染对贝类的毒性效应。结果表明，无论PFOS单独暴露还是与微塑料共暴露，PFOS在翡翠贻贝体内的生物富集都呈现明显的剂量效应关系，微塑料通过影响贻贝中PFOS的生物富集而影响贻贝内脏团的氧化应激响应；PFAS的生物富集量影响其对河蚬的毒性效应，因此PFOS对河蚬的影响大于F-53B；由于PE和PVC微塑料的粒径、密度的差别，导致PE微塑料对河蚬内脏团的组织损伤和转录组变化影响更大；PFAS和MPs联合暴露通过激活河蚬体内的粘着斑、吞噬体和核苷酸结合寡聚结构域（NOD）样受体信号通路，诱导氧化应激，致使鳃、消化腺、肠道和性腺出现严重的组织损伤，同时使肠道菌群紊乱甚至产生致病菌，最终导致河蚬的天然免疫响应。综上所述，PFAS和MPs的联合暴露通过影响PFAS的生物富集从而加剧对河蚬在氧化应激、组织损伤和免疫响应等方面的毒性作用。本研究为海洋环境和内陆河流的水质评价、新污染物水质基准的建立以及微塑料和全氟及多氟烷基化合物的风险控制提供了重要的科学依据。