Féderation de recherche Fabri de Peiresc

A laboratory model for plastic fragmentation in the turbulent ocean

Orateur : Christophe Brouzet

Abstract : While marine plastic pollution is ubiquitous and represents a global environmental threat, fundamental questions related to the fate of plastic debris in oceans remain poorly understood. Indeed, several studies have recently noticed a tremendous and unexpected lack of floating microplastic debris smaller than 1 mm, compared to what is expected from the current knowledge of plastic fragmentation. However, the description of the fragmentation process of marine plastic debris remains evasive. Here, I will present a physical model for the fragmentation of plastic debris in the turbulent upper layer of the ocean. Using laboratory experiments on the fragmentation of brittle fibres in a turbulent flow complemented by numerical simulations and theoretical analyses, our results demonstrate that the fragmentation process is limited at small scales by a physical cut-off length, independent of the brittleness of the fibres and originating from the fluid-structure interactions between the debris and the surrounding turbulent flow field. Such mechanism of the process at small scales can explain the observed lack of small fragments in the ocean and therefore paves the way for a thorough understanding of marine plastic fragmentation.

Date et lieu : Séminaire en ligne sur Zoom, le mercredi 25 novembre à 11h00