LAUSR

Abstract Microplastic (MP) pollution has raised public concerns in recent decades globally due to its wide global spreading and potential toxicity. Most of existing studies have focused on MP pollution in marine, freshwater, and sediment systems. However, much less research attention has been paid to soil, which is a major sink of MPs. Furthermore, research interest in MPs in groundwater is even lower than that in soils. There is a critical need to digest and summarize the existing knowledge and the latest advancements to promote research on MP pollution in soils and groundwater. As the first of its kind, this work provides a systematical review of the newest knowledge on occurrences, sources, analytical methods, and impacts of MPs in both soils and groundwater. It first outlines the characteristics (global occurrences, sources, and pathways) of MP pollution in soils and groundwater. Commonly used analytical methods including sample collection (sites, tools, depth, points, and quantity), sample preparation (drying and sieving), extraction (separation, digestion, etc.), identification (visual sorting, chromatography, and vibration spectroscopy), and quality assurance/quality control are then systematically reviewed. Furthermore, the risks and impacts of MPs on soil properties, plants, animals, and antibiotic resistance genes (ARGs) between microorganisms and humans are discussed. At the end, this review also identifies the knowledge gaps and points out potential directions for future research.