Physical Beaching Process of Microplastic Particles from Regular Waves

Microplastic pollution is a significant problem around the globe. However, the transport dynamics of these particles are not well understood, specifically with how microplastics accumulate in coastal and beach environments. We consider the physical beaching process for microplastic particles due to incident waves through laboratory wave flume experimentation. With buoyant plastic rods and disks starting near the still water line on an impermeable beach, the particle responses are observed during incident regular waves. Previous experiments have shown that for flow driven by solitary waves, the proximity of the particle starting location to the still water line influences the particle fate with respect to beaching. We implement surface particle image velocimetry (PIV) to measure the flow field velocity in the swash zone. We combine PIV data with particle tracking measurements of the plastic rods and disks to calculate the slip velocity of the flow on the particles. We aim to observe the dynamics dictating the fate of non-spherical nearshore plastic particles and quantify the statistics of plastic particle beaching based upon the parameters of incident waves and the particle Stokes number.