Short-term buoyant microplastic transport patterns driven by wave evolution, breaking, and orbital motion in coast

Area of Science:

• Environmental Science
• Oceanography
• Coastal Engineering

Background:

• Growing concern over microplastic pollution in marine environments.
• Waves significantly impact coastal flow patterns and material transport, including microplastics.
• Understanding microplastic movement in the surf zone is crucial for effective management.

Purpose of the Study:

• To investigate the short-term movement of buoyant microplastics in coastal surf zones.
• To analyze the influence of wave transformation, breaking, and orbital motion on microplastic transport.
• To identify key factors affecting microplastic pathways in different coastal bathymetries.

Main Methods:

• Utilized a Lagrangian Particle Tracking Model (PTM).
• Coupled PTM with an Eulerian wave-current interaction model for coastal hydrodynamics.
• Simulated microplastic movement under various surf zone conditions.

Main Results:

• Lighter and larger buoyant microplastics were observed to reach beaches more readily on uniform coastlines.
• Wave breaking was identified as a critical factor for accurate microplastic transport prediction in the surf zone.
• Rip-currents in non-uniform bathymetry were shown to transport buoyant microplastics offshore, out of the surf zone.

Conclusions:

• Microplastic transport in surf zones is complex and influenced by particle properties and wave dynamics.
• Accurate modeling must incorporate wave breaking to predict microplastic fate.
• Coastal geomorphology, such as rip-currents, plays a significant role in redistributing microplastics offshore.