Microplastics in bays: Transport processes and numerical models

Microplastics (100 nm < plastic particle size <5 mm) pose a significant threat to aquatic environments, impacting ecosystems, water quality, and sediment health. Coastal bays, with their semi-enclosed nature and unique hydrodynamic conditions, are particularly susceptible to microplastic accumulation. This review examines the various processes influencing the movement and distribution of microplastics in coastal bays. The study identifies dominant physical processes such as wind, currents, tides, and fronts that affect microplastic fate. Recent modelling efforts are reviewed, emphasizing the importance of accurate simulations for understanding microplastic distribution and testing mitigation strategies. Simulation models are crucial for identifying microplastic movement patterns, accumulation zones, and the effectiveness of mitigation measures. This review provides guidelines for selecting appropriate models to support effective management and intervention measures, ultimately contributing to the reduction of microplastic pollution in bays. Key research gaps and priorities are also discussed to guide future studies in these critical and vulnerable areas of our planet.