Microplastic Pollution in the Soil Environment: Characteristics, Influencing Factors, and Risks

As plastic products are widely used in all walks of life, plastic waste is also accumulating in the environment. Today, microplastic pollution in the soil environment has become an environmental issue of global concern. Compared with the water environment, the research on microplastics in the soil environment is relatively lacking. Based on the above situation, this paper systematically reviews the distribution characteristics, influencing factors, and environmental and ecological risks of microplastics in the soil environment. The abundance, distribution characteristics, and impacts of microplastics in soils globally in recent years are reviewed in detail. Our review suggests that most scholars only focus on the surface soil, and the determination of the accumulation of microplastics in the soil as a whole is still lacking, and there is still no uniform standard for sampling techniques, extraction methods, analytical procedures, and even expression units for soil microplastics. The distribution of microplastics in soil is affected by human factors, natural factors, and the physical and chemical properties of the plastics themselves. We also focused on the analysis of the environmental risks arising from the accumulation of microplastics in soil interacting with metals and organic pollutants, and found that large research gaps exist in the interaction between microplastics and pollutants in the soil and the mechanism of compound pollution. The impact and ecological risks of microplastics on animals, microorganisms, and plants in the soil are explained. Moreover, key suggestions for future research are presented based on the current research status, and we call for more efforts focusing on the occurrence and fate of microplastics in the soil environment.