[Research Progress for the Toxic Effects of Microplastics on Soil Animals and Plants]

Terrestrial ecosystems represent the most direct and principal reservoirs of plastic contamination on Earth. The toxic effects of microplastic exposure on terrestrial plants have been analyzed from the perspectives of direct toxicity, indirect toxicity, and combined toxicity with other pollutants. By investigating the impacts on the growth, behavior, and oxidative stress responses of soil animals, the toxicological patterns of microplastics have been elucidated. Moreover, the primary factors influencing the toxicity of microplastics on both fauna and flora have been discussed based on current research. The results indicated that for the majority of terrestrial plants, microplastics could inhibit seed germination, adhere to root surfaces, enter the plant body and induce oxidative stress, inhibit photosynthesis, and cause cellular and genetic toxicity. Soil animals could ingest and accumulate microplastics to varying extents, resulting in toxic effects such as aberrant gene expression, oxidative stress, intestinal toxicity, and alterations of growth and behavior on the genetic, cellular, tissue, and individual levels. Furthermore, these effects were also linked to microplastic additives and the adsorbed pollutants. The impact of microplastics on terrestrial plants and animals at environmentally relevant concentrations cannot be overlooked, with particle size emerging as a critical factor influencing toxic effects. The findings provide a basis for assessing the ecological risks of microplastics in soil environments and offer insights into future research directions.