Occurrences and impacts of microplastics in soils and groundwater

Microplastic (MP) pollution has raised public concerns in recent decades globally due to its slow degradation and potential toxicity. Most studies have focused on MP contamination in marine, freshwater, and sediment systems. However, much less research attention has been paid to the terrestrial environment, which is a major sink of MPs. This chapter summarizes global occurrences and sources of MPs in soils and groundwater. Commonly used analytical methods including sample collection (sites, tools, depth, approaches, and quantity), sample preparation (drying and sieving), extraction (separation, digestion, and filtration), and identification and quantification (visual sorting, chromatography, and vibration spectroscopy) are reviewed. Furthermore, the risks and impacts of MPs on soil structure and properties, plants, animals, microbiota, and human beings are discussed. Case studies of MP contamination in groundwater and research perspectives of MPs in soils and groundwater are also provided.