Microplastic Research Should Embrace the Complexity of Secondary Particles
Walter R. Waldman, Matthias C. Rillig
Abstract
R esearch identifying the ubiquitous presence of micro- plastics in the environment has accelerated further research to investigate their environmental behavior and fate.Whether a primary microplastic (manufactured microbeads, fibers, pellets) or secondary microplastic (larger plastic debris breaking into smaller fragments), 1 their fate in the environment is influenced significantly by the extent and nature of chemical and physical alteration under environmental conditions.Investigating and quantifying the nature and extent of this chemical and physical change is fundamental to more accurately describe the ultimate environmental fate and behavior of microplastics in the environment.However, this is an area that is often overlooked in microplastics research, or it is approached in a nonstandardized way.For example, a Web of Science search of the term "microplastic*" in 2019 returned 291 papers from three journals publishing the highest number of microplastics papers.Of these 291 papers, 77 described experiments performed in the laboratory with microplastics produced, purchased, or collected by the authors, and only five papers (approximately 6.5%) compared degraded and nondegraded samples to assess the effect of weathering on experimental outcomes.