Different mulch films, consistent results: soil fauna responses to microplastic

Area of Science:

• Environmental Science
• Soil Ecology
• Ecotoxicology

Background:

• Agricultural plastic mulch films contribute to soil microplastic pollution.
• Limited data exists on the impact of microplastics, especially biodegradable types, on soil organisms.

Purpose of the Study:

• To investigate the effects of polyethylene (PE) and biodegradable (PLA/PBAT) microplastics on soil fauna reproduction and subcellular responses.
• To assess potential recovery from microplastic exposure.

Main Methods:

• Exposure of Folsomia candida (collembolan) and Eisenia fetida (earthworm) to PE and PLA/PBAT microplastics (up to 10 g/kg dw).
• OECD guidelines 232 and 222 were followed for reproduction tests.
• Subcellular responses (GST, CAT, AChE, ROS) in E. fetida were analyzed, including post-exposure recovery.

Main Results:

• No significant impact on E. fetida and F. candida reproduction observed at tested concentrations.
• Increased glutathione S-transferase (GST) activity in E. fetida with higher microplastic concentrations.
• No significant changes in catalase (CAT), acetylcholine esterase (AChE), or reactive oxygen species (ROS) levels.

Conclusions:

• Mulch film-derived microplastics did not significantly affect the reproduction of tested earthworm and collembolan species.
• A slight induction of the detoxification enzyme GST was noted, but overall stress levels remained unaffected.
• Further research may be needed to fully understand long-term ecological implications.