Research Progress on Occurrence Patterns, Source Apportionment and Environmental Risk Assessment for Microplastics in Soil

Plastic waste degradation in the environment generates microplastics(< 5 mm), posing potential risks to soil physicochemical properties, terrestrial ecosystems, and human health. However, current research on the occurrence patterns, source apportionment methods, and environmental risk assessment of soil microplastics remains limited. To support soil microplastic pollution management and remediation, this review synthesizes the occurrence patterns of microplastics from various perspectives including abundance, polymer types, particle size, color and shape. Source apportionment methods, including pollution characteristic analysis, emission inventory, multivariate statistical modeling, and co-pollutant assisted identification are systematically introduced. Furthermore, this review evaluates the advantages and limitations of various risk assessment frameworks for soil microplastics, identifies the main challenges therein, and proposes future research directions. Firstly, there is need to accelerate the establishment of standardized analytical protocols for soil microplastics to provide multidimensional and accurate information for source identification and risk assessment; Secondly, strengthening fundamental research on source apportionment and establishing a robust source information database for soil microplastics is paramount; Thirdly, enhancing the research on risk assessment methods by developing a comprehensive toxicological database, quantifying the synergistic effects of composite pollution and clarifying the influence of factors on environmental risks, such as particle size, shape, color, and aging degree is necessary. These efforts will provide a scientific basis for the effective prevention and control of soil microplastic pollution risks.