State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing, 210093, China.
Shandong Province Metallurgical Engineering Co. Ltd., Jinan, 250101, China.
J Hazard Mater. 2020 Jun 15;392:122346. doi: 10.1016/j.jhazmat.2020.122346. Epub 2020 Feb 19.
Microplastics (MPs) in the environment usually undergo extensive weathering and can transport pollutants to organisms once being ingested. However, the transportation mechanism and effect of aging process are poorly understood. This study systematically investigated the desorption mechanisms of pharmaceuticals from pristine and aged polystyrene (PS) MPs under simulated gastric and intestinal conditions of marine organisms. Results showed that the increased desorption in stomach mainly depended on the solubilization of pepsin to pharmaceuticals and the competition for sorption sites on MPs via π-π and hydrophobic interactions. However, high desorption in gut relied on the solubilization of intestinal components (i.e. bovine serum albumin (BSA) and bile salts (NaT)) and the competitive sorption of NaT since the enhanced solubility increased the partition of pharmaceuticals in aqueous phase. Aging process suppressed the desorption of pharmaceuticals because aging decreased hydrophobic and π-π interactions but increased electrostatic interaction between aged MPs and pharmaceuticals, which became less affected by gastrointestinal components. Risk assessment indicated that the MP-associated pharmaceuticals posed low risks to organisms, and warm-blooded organisms suffered relatively higher risks than cold-blooded ones. This study reveals important information to understand the ecological risks of co-existed MPs and pollutants in the environment.
环境中的微塑料（MPs）通常会经历广泛的风化作用，一旦被摄入，就可以将污染物运输到生物体中。然而，老化过程的运输机制和影响还了解甚少。本研究系统地研究了在模拟海洋生物的胃和肠条件下，原始和老化聚苯乙烯（PS） MPs 中药物的解吸机制。结果表明，胃中解吸的增加主要取决于胃蛋白酶对药物的溶解作用，以及通过π-π和疏水相互作用在 MPs 上竞争吸附位点。然而，肠道中的高解吸依赖于肠道成分（即牛血清白蛋白（BSA）和胆汁盐（NaT））的溶解作用以及 NaT 的竞争吸附作用，因为增强的溶解度增加了药物在水相中的分配。老化过程抑制了药物的解吸，因为老化降低了疏水和π-π相互作用，但增加了老化 MPs 和药物之间的静电相互作用，从而使它们受胃肠道成分的影响较小。风险评估表明，与 MPs 相关的药物对生物体的风险较低，而温血生物比冷血生物遭受的风险更高。本研究揭示了理解环境中共存的 MPs 和污染物的生态风险的重要信息。
