Habitat heterogeneity regulates PFAS behavior and ecological risks in estuarine and coastal wetlands.

Per- and polyfluoroalkyl substances (PFAS) are persistent contaminants with pronounced surface activity and partitioning between water and particles, and habitat heterogeneity regulates their transport, redistribution and biological exposure within estuarine and coastal wetlands. This review synthesizes multimodal evidence from field surveys of water, particles, sediments, and biota, together with mechanistic studies of PFAS partitioning, transport, and biological responses. The resulting habitat-based framework links habitat heterogeneity to PFAS partitioning, transport, biological exposure, and food-web transfer, and relates these processes to consequences for biogeochemical cycling, biodiversity, and ecosystem services. Focusing on mangroves, salt marshes, and tidal flats, the study compares how hydrodynamic and salinity gradients, together with particle and sediment properties including organic carbon, clay, and transparent exopolymer particles, mediate PFAS retention and shape spatial exposure baselines for benthic organisms. Bioengineering effects, nursery-ground dynamics, and species habitat use can modify trophic exposure pathways, while reported food-web outcomes vary among systems, with trophic magnification observed for some long-chain PFAS and apparent biodilution reported in others. Building on these findings, habitat specific guidance is proposed for integrated management and risk assessment, emphasizing source reduction, explicit inclusion of the sediment phase, and PFAS multi-media evaluation supported by passive and non-target screening and bioaccumulation metrics interpreted in the context of life history and habitat use.