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

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.