[M-IS17] Ocean Plastics, an earth science perspective

[MIS17-P05] An effect of beach fragmentation process on sorting of ocean mesoplastics and microplastics

*Koki Nakajima¹, Atsuhiko Isobe² (1.Kyushu University, 2.Research Institute for Applied Mechanics, Kyushu University)

Keywords:microplastics, selective transport, fragmentation

We examined the effect of beach fragmentation process on inshore-offshore distribution of ocean mesoplastics(MeP) and microplastics(MiP) by using numerical model. In accordance with a previous study (Isobe et al., 2014) based on both observations and numerical model approach, MePs areis transported toward the shore, while MiPs spread widely by “sorting” due to buoyancy and Stokes Drift. However, their model did not incorporate a breaking process of MeP to MiP, and so the sorting process should be further validated. In this study, we confirmed sorting of plastics particles by numerical model incorporating fragmentation from MeP to MiP on shore. In addition, we examined dependence of plastics distribution on timescale of landing/fragmentation/redrift with shore.