An extensive characterization of various environmentally relevant microplastics - Material properties, leaching and ecotoxicity testing

Microplastics in the environment occur in different sizes and shapes and are made of various polymers. There-fore, they also considerably differ in their properties and ecotoxicity. However, the majority of microplastics research uses pre-made spherical microplastics, which practically do not exist in the environment. Our work focused on a comprehensive study of six different types of microplastic that were prepared to simulate common microplastics found in the environment. All types of microplastics where chemically and physically characterized using Fourier-transform infrared spectroscopy, thermal analysis, field-emission scanning electron microscopy, optical microscopy and laser diffraction analysis. The specific surface area was determined using the BET method. Furthermore, effects of microplastics and microplastic leachates on a common duckweed (Lemna minor) were evaluated. All tested microplastics did not affect specific growth rate and chlorophyll a content in duckweed, while microplastics with a rough surface and sharp edges caused a significant reduction of duckweed root length. Microplastics made of Bakelite also showed an intensive leaching, which increased their ecotoxicity potential. Natural particles used as a control did not have any negative effect on duckweed. Overall, microplastic particles have significantly different ecotoxicity profiles depending on their physico-chemical properties. Therefore, the testing of environmentally relevant particles and their proper characterization, as well as the testing of microplastic leaching properties, is crucial for understanding of microplastics ecotoxicological potential. (C) 2021 The Author(s). Published by Elsevier B.V.

Automated summary

Different types of microplastics have varying effects on duckweed, with rough-surfaced and sharp-edged microplastics significantly reducing root length, while Bakelite-made microplastics exhibit high leaching and ecotoxicity potential. In contrast, natural particles have no negative impact on duckweed, indicating that the ecotoxicity of microplastics is influenced by their physico-chemical properties.