Plastic pollution interception by vegetation: A mechanistic review across diverse habitats

Plastic pollution is intensifying across freshwater-coastal continua and impacts terrestrial, freshwater, and marine habitats. While vegetated areas are vital sinks, they are approaching a critical tipping point at which accumulation transforms these habitats from natural filters into toxic hotspots. This review synthesizes data from nearly 199 peer-reviewed studies to understand how vegetation traps macro- and microplastics in ecosystems such as mangroves, salt marshes, seagrass meadows, coastal dunes, and riparian zones, and explains the implications for exposure, fate, and risk management. We examine how the main factors affecting retention, such as plastic physicochemical properties (size, shape, density, weathering), vegetation structural characteristics (root and stem complexity, canopy architecture), and environmental conditions (water flow, geomorphology, climate), jointly influence retention dynamics. Results show vegetated ecosystems capture ∼2.05-2.82 times more microplastics than non-vegetated areas. Plastic retention occurs mainly through two pathways: (1) physical interception and flow reduction at large scales, and (2) micro-scale adhesion via eco-corona formation, and subsequent biofilm/EPS development that promote particle sticking and persistence and limit resuspension. However, significant uncertainties remain about nanoplastic-plant interactions, long-term accumulation and remobilization, and climate impacts on exposure and fate, particularly under shifting hydrodynamic and geomorphic regimes. A crucial sink-hazard paradox exists: although vegetation effectively traps plastics, this accumulation transforms sediments into dangerous hotspots by concentrating toxic additives (e.g., flame retardants), co-transporting persistent organic pollutants, and promoting potentially harmful biofilms. We recommend a research roadmap that includes standardized protocols and reporting units, advanced process-based modeling frameworks, climate-resilience scenarios, and nature-based solutions for shifting vegetation from passive pollution sinks to active, managed mitigation tools. Implementing these recommendations is crucial for developing effective, evidence-based strategies that balance pollution control with hazard containment in vegetated ecosystems.