Macro- and microplastics leachates: Characterization and impact on seed germination

Abstract

Although plastic mulch enhances crop yield, its removal and disposal present significant challenges, contributing to macro- and microplastic pollution in agricultural soils. The adverse effects of this pollution on soil and plant health are not fully understood but may stem from the plastic particles or the toxicity of leached chemical additives. This study assessed the impact of macro- and microplastics from nondegradable LDPE-based (LDPEb) and biodegradable PBAT-based (PBATb) mulch films, along with their leachates, on the germination of three plant species. After seven days of incubation, PBAT mulch leached compounds that significantly inhibited Arabidopsis germination, while cotton and tomato exhibited notable tolerance. Notably, PBATb mulch released a higher concentration of compounds, whereas LDPEb mulch exhibited a greater diversity of leached chemicals. Microplastic particles alone did not hinder seed germination, indicating that plastic toxicity primarily arises from the leachates. Many of these leached compounds lack global regulation and hazard information, underscoring the urgent need for further investigation into their environmental impacts and the development of appropriate regulatory frameworks to mitigate the potential toxicity of chemicals from conventional and biodegradable mulches. Plastic pollution is widely reported in the agricultural environment, with over 13,000 chemicals associated with distinct plastic applications. Understanding whether macro- or microplastics from mulch films or their leachates hamper seed germination is pivotal for developing strategies to tackle such environmental issues. Leachates from macro- and microplastics at different concentrations ( Table S1 ) were characterized. Here, we found that the leachates can impact seed germination and that most compounds leached from the tested mulch films are still unregulated worldwide, lacking hazard information. Therefore, more attention should be paid to the environmental hazards of macro- and microplastics and their respective leachates. • Chemical compounds are leached from conventional and biodegradable plastic mulch. • PBATb mulch released a higher concentration of leachates than LDPEb after one week. • High concentration of PBATb leachates reduced Arabidopsis seed germination. • Negligible microplastic particle effects imply seed harm is mainly from leachates. • Most leached compounds are unregulated worldwide and lack hazard information.

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