Microplastics formation based on degradation characteristics of beached plastic bags

Highlights: • Pollution from plastic bags is a significant issue in the global environment. • An interdisciplinary approach is employed to examine beached plastic bags. • For oxodegradable plastic bags only starch degradation is observed. • Plastic bags can break into microplastics before major chemical degradation. • Chemical degradation of plastic bag surface also leads to fragmentation. Environmental pollution from plastic bags is a significant issue in the global environment. Plastic bags can be transferred by the wind and ocean currents everywhere in the three dimensions and be fragmented into small particles, termed film-shaped microplastics. The purpose of this study is to provide insights on the degradation of beached plastic bags. Monitoring and sampling were performed to determine plastic bag fragmentation and the possible mechanisms. On selected samples, various spectroscopic techniques and microscopy were used. Before the imposition of the ^green plastic bag fee in Greece, field monitoring suggested that the majority of the coastal plastic bags were fragmented whereas after the ^green fee, less fragmented bags were observed. Evidence of three degradation mechanisms were observed in this study. For oxodegradable plastic bags, degradation takes place for the starch additives and the polymer part stays in the environment as microplastic particles. For thin light density polyethylene plastic bags, mechanical fragmentation takes place in the environment creating microplastics before significant chemical alterations in functional groups were observed and once chemical alteration (oxidation) is observed, fragmentation (of HC or CC bonds) is also taking place. Thus, regulating thin plastic bags usage removes problems related to plastic bags but also to film-shaped microplastics.