School of Environment, Hangzhou Institute for Advanced Study, UCAS, Hangzhou 310024, China.
State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, P.O. Box 2871, Beijing 100085, China.
Environ Sci Technol. 2022 Dec 20;56(24):17694-17701. doi: 10.1021/acs.est.2c05669. Epub 2022 Dec 8.
Nanoplastics (NPs) have been successively detected in different environmental matrixes and have aroused great concern worldwide. However, the fate of NPs in real environments such as seawater remains unclear, impeding their environmental risk assessment. Herein, multiple techniques were employed to monitor the particle number concentration, size, and morphology evolution of polystyrene NPs in seawater under simulated sunlight over a time course of 29 days. Aggregation was found to be a continuous process that occurred constantly and was markedly promoted by light irradiation. Moreover, the occurrence of NP swelling, fragmentation, and polymer leaching was evidenced by both transmission electron microscopy and scanning electron microscopy techniques. The statistical results of different transformation types suggested that swelling induces fragmentation and polymer leakage and that light irradiation plays a positive but not decisive role in this transformation. The observation of fragmentation and polymer leakage of poly(methyl methacrylate) and poly(vinyl chloride) NPs suggests that these transformation processes are general for NPs of different polymer types. Facilitated by the increase of surface functional groups, the ions in seawater could penetrate into NPs and then stretch the polymer structure, leading to the swelling phenomenon and other transformations.
纳米塑料（NPs）已在不同的环境基质中相继被检测到，引起了全球的高度关注。然而，纳米塑料在海水等真实环境中的命运仍不清楚，这阻碍了对其环境风险的评估。在此，采用多种技术在模拟太阳光下监测了聚苯乙烯 NPs 在海水中的颗粒数浓度、粒径和形态演变，历时 29 天。结果表明，聚集是一个连续的过程，不断发生，并明显受到光照射的促进。此外，通过透射电子显微镜和扫描电子显微镜技术证实了 NP 的肿胀、碎裂和聚合物浸出的发生。不同转化类型的统计结果表明，肿胀会导致碎裂和聚合物泄漏，而光照射在这种转化中起着积极但不是决定性的作用。聚甲基丙烯酸甲酯和聚氯乙烯 NPs 碎裂和聚合物泄漏的观察表明，这些转化过程对于不同聚合物类型的 NPs 是普遍存在的。受表面官能团增加的促进，海水中的离子可以渗透到 NPs 中，然后拉伸聚合物结构，导致肿胀现象和其他转化。
