Implications of a New Test Facility for Fragmentation Investigations on Virgin (Micro)plastics

Littered plasticsare partly introduced into water bodies, ultimatelytransporting this waste to the shores and oceans. At the shore, ultraviolet(UV) radiation (also present in other environmental compartments)and wave breaking cause plastics to degrade and fragment into smallerparticles, called microplastics, if below 5 mm. Since these plastics'surfaces can act as vectors for hydrophobic (toxic) chemical substances(e.g., per- and polyfluoroalkyl substances (PFAS)) and leach (toxic)chemicals into the water, the increase in the surface area throughthe fragmentation of plastics becomes relevant. Studies investigatingdifferent effects on the fragmentation of plastics have mostly disregardeda sufficient mechanical component for fragmentation, focusing on degradationby UV radiation. Therefore, this study investigated the impact ofthe mechanical fragmentation drivers, wave impact, and sediment abrasionon the fragmentation of expanded polystyrene (EPS), high-density polyethylene(PE-HD), and polyethylene terephthalate (PET) particles. In a newlydesigned test facility called Slosh-Box, the mentioned impacts wereinvestigated concurrently. The results reveal that the mechanicalimpacts alone are sufficient for plastic fragmentation, and the testfacility is suitable for fragmentation investigations. Furthermore,the increase in surface area was determined via scanning electronmicroscopy. For EPS, the surface area increased more than 2370-fold,while for PE-HD and PET, surface areas increased between 1 and 8.6times. Concluding from the results, the new test facility is suitablefor plastic fragmentation studies. In addition, sediment was revealedto be a relevant fragmentation driver, which should be included inevery experiment investigating the fragmentation of plastic in a nearshoreenvironment independent of other drivers like UV radiation. Microplastic fragmentation is a scarcelyresearched topic.This study finds that virgin plastics can fragment solely by sediment-inducedabrasion in a newly developed test stand, increasing the surface areabetween 1 and 2370 fold.