Microplastic Pollution in Freshwater Sediments: Spatial–Temporal Patterns

Purpose of review: Although research on microplastic (MP) pollution in freshwater has increased, much remains unknown about the fate and distribution of this pollutant in sediments. This review provides a global perspective on how research efforts and data collection are distributed, also exploring recent studies on factors that play a key role in MPs transport and influence MP distribution in freshwater sediments worldwide. Recent findings: The role of human activities, precipitation and stormwater run-off, water flow, sediment grain size, and land use on the spatial and temporal distribution of MPs in sediments has been demonstrated, highlighting the complex interactions between these factors and MP pollution. MPs have been found in sediments of rivers, tributaries, and lakes, from urbanized to remote areas, with variations across regions, ecosystems, and temporal scales. To date, most studies are concentrated in Asia, with limited representativeness of other continents. In addition, limitations remain, as data variations between studies may result from different scales or analytical methods. Summary: This review provides an overview of the spatiotemporal variation of MP pollution in freshwater sediments, highlighting knowledge gaps and challenges. Future research should aim to more geographically balanced studies, addressing both temporal and spatial aspects to better assess the long-term environmental and ecological impacts of MPs in freshwater systems.