微塑料对多环芳烃的吸附解吸行为及其生物可给性影响

In recent years, microplastic pollutions have been major global environmental issues, the environmental behavior and ecological effects of microplastics have gradually become the focus of researchers. Microplastics are highly hydrophobic, which can concentrate various persistent organic pollutants. Hence, microplastics have the potential to be harm for environment and human health. The hypothesis whether the sorbed contaminants can be transferred from ingested plastics to marine organisms need further studied. The objectives of this study were investigated for the adsorption and desorption behavior of PAHs on microplastics and the impacts of microplastics on PAHs bioaccessibility. Microcosmic characterization, adsorption-desorption experiments and in vitro simulated digestion experiments are adopted. The investigation aims to (1) reveal the impacts of microplastics structural characteristics, PAHs physicochemical properties, aging and digestive fluid composition on PAHs adsorption-desorption and PAHs bioaccessibility; (2) address the underlying mechanisms for microplastics adsorption and desorption; (3) reveal the relationship between the critical structural characteristics of microplastics and PAHs bioaccessibility. The results will promote thoroughly understanding of interface behavior between microplstics and hydrophobic organic compounds, and better assessment of microplstics ecological risks.

近年来微塑料污染迅速发展成为全球性的重大环境问题，其环境行为与生态效应已成为当前环境科学领域研究的热点。微塑料具有很强的疏水性，能富集多种持久性有机污染物，对环境安全与人类健康构成巨大危害。然而对于微塑料携带的污染物能否有效地转移到生物体内仍缺乏深入研究。本项目将围绕微塑料与多环芳烃(PAHs)的吸附-解吸行为及对PAHs生物可给性的影响展开深入研究。拟采取微观表征、宏观吸附-解吸及体外消化模拟相结合的方式，探讨微塑料结构特征、PAHs理化性质、老化效应及消化液成分对微塑料吸附-解吸附PAHs及其生物可给性的影响，最终阐明微塑料对PAHs的吸附-解吸机制，揭示微塑料结构特性与微塑料中PAHs生物可利用度的相关规律。本项目的完成，将为深入认识微塑料与疏水性有机物的界面行为及客观评价微塑料的潜在生态风险提供理论依据。

本项目围绕微塑料污染现状及其与有机污染物相互作用机制开展了以下研究：(1) 比较研究了聚己二酸对苯二甲酸丁二酯、聚乙烯和聚苯乙烯微塑料对多环芳烃中菲的吸附/解吸行为，发现聚己二酸对苯二甲酸丁二酯微塑料的吸附和解吸能力高于聚乙烯和聚苯乙烯微塑料，且高于环境中的一般天然碳质吸附剂(干酪根、生物炭和炭黑)。对吸附/解吸等温线的比表面积归一化结果发现微塑料的吸附/解吸程度与其橡胶态含量呈正相关关系。盐度、溶解有机质和铜离子这三种水化学因子对微塑料的吸附呈现出相同的影响趋势，但影响程度有所不同，主要取决于微塑料的橡胶态含量。研究说明微塑料的结晶特征对微塑料与疏水性有机污染物的相互作用具有重要影响。（2）针对珠江口三块红树林湿地沉积物中微塑料污染状况开展调查，研究结果发现，与国内外近岸海域沉积物相比，珠江口红树林湿地沉积物中微塑料丰度(100–7900个∙kg-1 dw)处于较高水平。深圳红树林湿地沉积物中微塑料丰度显著高于广州和珠海，当地人口密度及国内生产总值与该地微塑料丰度成显著正相关。红树林沉积物中以尺寸<500 μm的微塑料为主，占所有微塑料样品的比例为69.4%。聚乙烯/聚丙烯共聚物、绿色/黑色、纤维/碎片分别是所有微塑料样品中最主要的类型、颜色和形状。卤系阻燃剂与微塑料丰度的相关性表明，多溴二苯醚、十溴二苯乙烷、1,2-双(2,4,6-三溴苯氧基)乙烷和六溴环十二烷可能与微塑料具有相同的污染源。