College of Natural Resources and Environment, Northwest A&F University, Yangling, Shaanxi 712100, China; Key Laboratory of Plant Nutrition and the Agri-Environment in Northwest China, Ministry of Agriculture, Yangling, Shaanxi 712100, China; State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing 210093, China.
State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing 210093, China.
Sci Total Environ. 2021 May 10;768:144969. doi: 10.1016/j.scitotenv.2021.144969. Epub 2021 Jan 30.
After being discarded into the environment, the microplastics (MPs) will undergo weathering effects. However, the low degradation rate of MPs in natural processes greatly limits the understanding of long-term aging behavior. By critically reviewing 82 articles in Web of Science from 2015 to 2020, the paper summarized different laboratory technologies including light irradiation, chemical oxidation, heat treatment and γ-ray irradiation to simulate and accelerate the aging of MPs, and evaluated the feasibility by comparison with natural processes. The advantages of laboratory technologies are that aging conditions can be artificially controlled and that the labor and time costs can be saved, whereas the laboratory system is too simple to simulate complex aging processes in the environment. We further reviewed the potential impacts of aging process on the risks of MPs (i.e. physical injury, combined toxicity with external pollutants and chemical risk of additives and low-molecular products). The overall risks are seemingly enhanced by aging process due to the high ingestion by organisms, the strong interaction with pollutants and the release of MP-derived organic compounds. Further studies on the aging behavior of MPs should be focused on the laboratory techniques that can simulate multiple processes of natural aging, the long-term fragmentation behavior of MPs, the effect of aging on growth rate of biofilm in MPs and ingestion property by organisms, and the relationship between aging property of MPs and release rate of chemicals in leachates.
废弃到环境中后，微塑料（MPs）将经历风化作用。然而，MPs 在自然过程中的低降解率极大地限制了对其长期老化行为的理解。本文通过批判性地回顾了 2015 年至 2020 年在 Web of Science 上的 82 篇文章，总结了不同的实验室技术，包括光辐照、化学氧化、热处理和γ射线辐照，以模拟和加速 MPs 的老化，并通过与自然过程进行比较来评估其可行性。实验室技术的优点是可以人为控制老化条件，并且可以节省劳动力和时间成本，而实验室系统过于简单，无法模拟环境中复杂的老化过程。我们进一步综述了老化过程对 MPs 风险（即物理损伤、与外部污染物的联合毒性以及添加剂和低分子量产物的化学风险）的潜在影响。由于生物体的高摄取率、与污染物的强烈相互作用以及 MP 衍生的有机化合物的释放，老化过程似乎会整体增加风险。进一步研究 MPs 的老化行为应集中在可以模拟自然老化多个过程的实验室技术上， MPs 的长期碎片化行为，老化对 MPs 中生物膜生长速率和生物体摄取特性的影响，以及 MPs 的老化特性与浸出液中化学物质释放率之间的关系。
