环境条件下微塑料对多氯联苯在斑马鱼体内富集的影响

One of the potential risks of microplastics are that they can carry and transfer hydrophobic organic contaminants to organisms. Laboratory experiments have demonstrated that microplastics usually can enhance hydrophobic organic contaminants bioaccumulation in organisms significantly; however, modelling analysis showed that the carrier function of microplastics is very limited. This project is aimed to carry out studies under environmental conditions and combine laboratory exposure and modelling analysis together. Firstly, typical contaminants polychlorinated biphenyls (PCBs) will be used as model pollutants. We will study the sorption-desorption kinetics and equilibrium characteristics of PCBs on environmentalized microplastics, such as fibers, beads and fragments, under different water temperature or with the influence of dissolved organic matter and foodborne particles. Secondly, zebrafish will be chosen as the model animal. We will study the microplastics effects on PCBs transfer to and accumulation in zebrafish at "equilibrated" and "unequilibrated" states and different environmental conditions. Finally, we will apply contaminant partitioning and biokinetics models on the basis of laboratory experiments to illustrate the role of microplastics in bioaccumulation of hydrophobic organic contaminants. This project can increase our understanding about the microplastic carrier function and provide scientific basis for its ecological risk assessment.

微塑料能负载疏水性有机污染物并将其转运至生物体内被认为是其潜在风险之一。已有室内暴露实验表明微塑料往往可显著促进有机污染物在生物体内的累积，然而，模型分析结果却显示微塑料对污染物的载体作用十分有限。本项目拟在考虑环境条件的前提下，将室内暴露与模型分析相结合，首先以典型疏水性有机污染物多氯联苯（PCBs）为代表化合物，研究纤维、粒子和碎片等具有环境特征的微塑料在不同水溶液温度等条件下对PCBs的吸附-释放的动力学过程和平衡特征，以及溶解性有机质和食源性颗粒等对PCBs分配行为的影响；然后，以斑马鱼为模式生物，研究在“已平衡”和“未平衡”两种状态和上述各种环境条件下微塑料对PCBs向斑马鱼的迁移和累积作用；最后，在室内实验基础上，运用污染物平衡分配和生物动力学模型，揭示环境条件下微塑料对疏水性有机污染物生物富集的影响机制。本研究将增进人们对微塑料载体作用的认识，为其生态风险评估提供科学依据。

水体环境中的微塑料污染已经逐渐受到研究者们的广泛关注。但是除了微塑料自身的生物效应之外，微塑料对共存疏水性有机污染物的负载机制、生物累积和毒性效应的影响也亟需得到阐释。通过本项目的开展，我们实现了微塑料在水生生物体内的原位可视化观测，归纳了微塑料在不同营养级生物上的富集规律，并且发现在不同暴露方式下（水相和食物相），斑马鱼体内的微塑料累积特征和毒性效应差异显著。我们还选择了典型有机污染物多氯联苯（PCBs）作为模式化合物，重点研究了微塑料对共存有机污染物的载体效应和作用机制。我们明确了微塑料可以促进以添加态存在的共存污染物在生物体内的累积，并能够改变这些污染物对水生生物的毒性效应。因此，通过本项目的研究我们厘清了微塑料对共存的疏水性有机污染物的吸附和释放机制，揭示了环境条件下微塑料对这些污染物的生物累积和毒性效应的影响。我们认识到微塑料上共存的添加态污染物的释放可能会带来潜在的生态和健康风险，后续的研究中我们将尝试形成塑料添加剂设计—环境风险评估的互反馈模块，从而促进绿色化塑料的生产和使用。综上，本研究增进了人们对微塑料载体作用的认识，并为其生态风险评估提供了有力的科学依据。