Degradation of Microplastics in the Environment

Abstract

Microplastic debris in the environment degrades mechanically, chemically, and biologically. Degradation rates depend on polymer characteristics, such as structure, additives, and chemical composition, as well as environmental characteristics, such as temperature and humidity, depositional matrix (e.g., water, soil, sand, terrestrial versus aquatic), and depositional environment. The latter factor plays an integral role in determining whether microplastic particles are exposed to sunlight or buried beneath the water column or in the benthos, and in the amount of mechanical abrasion that occurs in settings such as beaches versus landfills. Although mechanical, chemical, and biological degradation can each break down microplastics into nanoplastics or oligomers and monomers, the combination of two or all three weathering processes normally interact to lead to microplastics degradation. In this chapter, the three types of degradation are summarized and examples are provided in which microplastics have been broken down in the environment and under simulated environmental conditions.