Global surface dispersion of marine debris under simple scenario

Christophe Maes

IFREMER  

ABSTRACT

Marine litter and plastic debris are ubiquitous nowadays in our global oceans and represent a potential health issue. However, the open question on the amount of plastic floating at the sea surface remains, and more generally, basic information and knowledge about the origins, where it is accumulating, and its transport pathways are still uncertain. From a positive point of view, the litter problem forces numerical modelers to identify the near-surface ocean dynamics required to tackle problems such as the distribution and transport pathways at the global ocean scales. In a recent study on the five regions of surface convergence at the scale of each oceanic basin, using a Lagrangian analysis, a convergent pathway connecting the South Indian subtropical region with the convergence zone of the South Pacific through the Great Australian Bight, the Tasman Sea and the southwest Pacific Ocean has been identified. This “super-convergent” dynamical pathway at the ocean surface is robust and permanent over a distance longer than 8000 km, and quite unique in the Southern Hemisphere. How this particular circulation affects the marine plastic litter under different scenarios reflecting inputs into the open ocean is the focus of the present study. The objective is to underline the importance of ocean dynamics in order to assess implications and consequences on the complex problem of marine litter.

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