Insights into the shape-dependent effects of polyethylene microplastics on interactions with organisms, environmental aging, and adsorption properties

• Published in: Scientific reports Vol. 13; no. 1; p. 22147
• Main Authors: Rozman, Ula, Klun, Barbara, Kuljanin, Aleksandra, Skalar, Tina, Kalčíková, Gabriela
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 13-12-2023; Nature Publishing Group; Nature Portfolio
• Subjects: 704/172; 704/172/169; 704/172/4081; Adsorption; Aging; Aquatic plants; Biofilms; Chlorophyll; Extracellular polymers; Floating plants; Humanities and Social Sciences; Ingestion; Methylene blue; Microorganisms; Microplastics; multidisciplinary; Organic compounds; Plant biomass; Plastic pollution; Polyethylene; Science; Science (multidisciplinary)
• ISSN: 2045-2322; 2045-2322
• DOI: 10.1038/s41598-023-49175-1

The shape-dependent effects of microplastics have been studied in the context of ingestion but have not been considered in other environmental processes. Therefore, we investigated how the shape of polyethylene microplastics (spheres, fragments, and films) affects interactions with plants, aging, and their adsorption properties. The shape had no effect on the growth rate and chlorophyll content of duckweed
Lemna minor
, but the fragments strongly adhered to the plant biomass and reduced the root length. The adsorption process of the model organic compound (methylene blue dye) was described by the same kinetic model for all shapes—the experimental data best fit the pseudo-second order model. However, twice as much methylene blue was adsorbed on films as on fragments and spheres. During environmental aging, most biofilm developed on films. The biofilm on spheres contained significantly less photosynthetic microorganisms, but twice as much extracellular polymeric substances (EPS) as on fragments and films. This suggests that the attachment of microorganisms to spherical particles is limited and therefore more intensive production of EPS is required for stable biofilm formation. From the results of this study, it is evident that the shape of microplastics significantly affects not only ecotoxicity but also other environmentally relevant processes.