Per- and polyfluoroalkyl substances in aquatic sediments: Global distribution, partitioning behavior, and ecological...

Per- and polyfluoroalkyl substances (PFAS) are persistent organic pollutants that accumulate across aquatic compartments, which include sediments, pore water, surface water (including microlayers), suspended particulate matter (SPM), fish, and other biota, causing long-term ecological impacts. This review analyzes the global distribution of PFAS in aquatic sediments, partitioning behavior across aquatic compartments, and ecological consequences of PFAS on sediment-dwelling organisms. PFAS in sediments are widespread globally, with the highest mean concentration (274.1 ng/g) found in the African continent, in addition to localized hotspots showing increased average levels in other continents. SPM consistently retains higher PFAS levels than sediments, while porewater concentrations exceed those of surface water (SPM > sediment, porewater > surface water), revealing overlooked exposure pathways. Sediment-bound PFAS exposes benthic organisms through dermal contact, ingestion, and trophic transfer, with bioaccumulation influenced by organism traits, sediment properties, and environmental factors. Although ecological risk quotient (RQ) values are generally low (RQ < 0.1), localized hotspots and species-specific sensitivities highlight the need for site-specific monitoring. Regulatory frameworks in the EU and United States remain focused on drinking and surface waters, lacking sediment-specific standards and leaving a critical policy gap. Thus, this review suggests sediments as an important yet underexplored reservoir of PFAS, indicating the importance of incorporating sediment compartments into monitoring, ecological risk assessment, and regulatory frameworks.