Progress on release and migration of plastic additives to ecological environment

塑料废弃物，尤其是粒径小于5 mm的微塑料造成的环境污染问题已引起全球的普遍关注。塑料制品在生产过程中常使用多种添加剂，以提高聚合物的性能并延长其使用寿命。然而，在废弃塑料制品的回收及自然老化过程中，这些添加剂会不断释放出来，对生态环境的安全与人类的健康产生威胁。综述了近年来国内外塑料添加剂的使用情况及其向生态环境释放与迁移等方面的研究进展，具体包括常用塑料添加剂的种类、废弃物塑料回收和塑料老化过程中添加剂向生态环境中的释放与迁移及机制等。未来需要更加关注绿色塑料添加剂的研发、废弃塑料回收工艺的改进以及关于塑料添加剂的释放、在各类环境介质中的迁移转化以及在生态系统各个圈层间的相互作用方面的系统性的研究，并构建相应的迁移模型评估塑料添加剂产生的生态风险。;The environmental issue caused by plastic waste, especially by micro-plastics with particle size less than 5 mm, has attracted the worldwide attention. During the production process of plastic products, many types of additives are often used to improve the performance of polymers and to extend the service life of plastic products. However, these additives may be released continuously during the usage, recycling and natural aging of plastic products, which will be a big threat to the ecological environment and human health. In this paper, research progress on the commonly used plastic additives and their release and migration to the ecological environment was reviewed, including the types and amount of additives commonly used in plastics, the release and migration of plastic additives to the environment media and organisms during the recycling process of plastic wastes and the aging of plastics, and the mechanisms involved. The functional additives commonly used in plastics include the antioxidants which are used to delay or inhibit the oxidative degradation of plastics due to light, heat, radiation and metal impurities, the flame retardants which are used to increase the flame resistance of polymers, the plasticizers which are used to improve the flexibility, durability and durability of polymer films, and to reduce crystallinity of polymer molecular chains, and the stabilizer which are used to slow or prevent thermal degradation and photodegradation of plastic polymer during processing or use. In the recycling process of waste plastics, a variety of organic and metal additives may be released to the atmospheric environment, soil and sediment and migrate to the organisms. During the process of plastic aging, additives will be released into the water and sediment, and migrate into organisms, causing toxicities. The migration mechanism of plastic additives proposed at present includes the following steps:diffusion of additives from the inside to the surface of plastics, desorption of additives from the surface of plastics, adsorption of additives on the surface of environmental media or organisms, and diffusion of additives in the environmental media or enrichment in organisms. In future, more attention should be paid to the development of green plastic additives, the improvement of technologies for plastic waste recycling, and systematic research on the release, migration and transformation of plastic additives in various environmental media as well as the interaction between various layers of the ecosystem. Besides, migration models are required to be established to assess the ecological risks of plastic additives in the natural environment.