Tsunami - triggered dispersal and deposition of microplastics in marine environments and their use in dating recent turbidite deposits

Microplastics have become widely dispersed throughout the marine environment in and around Japan since the 1960s, which correspond to the onset of mass plastic production and use in this country. Our study documents a possible abrupt microplastics depositional event in continental shelf and deep-sea environments triggered by a tsunami. The sediment layers contaminated by microplastics correspond with sedimentary horizons where 137Cs signals were measured, indicating deposition after 1960s nuclear tests. The microplastics were observed in the 2011 Tohoku-Oki tsunami deposits. Tsunamis can thus contribute to the wide dispersal of microplastics from coastal to deep-sea areas, and these anthropogenic particles can be used to date very recent turbidite deposits.