Modeling the plastic dispersion and accumulation in the open ocean

Although the detection of plastic pollution at sea began a few decades ago within the different subtropical ocean gyres, regions far from any land, we now know that floating plastics and debris are ubiquitous in all ocean basins, ecosystems, habitats, and food webs, including in our food and sea salt. In addition to work for a better understanding of the contamination, the scope of investigation has broadened to include issues of sources, fate, and pathways in the physical and dynamic environment of the ocean, with a focus on answering a fundamental question: why does plastic accumulate in certain regions of the oceans? Several examples will be considered, based on global and regional ocean dynamics and down to the meso-scale eddies, to underline the need for a better monitoring and understanding of surface currents in order to tackle the marine pollution by debris and plastics. The general context is based on the holistic approach considering sources (land or sea scenario), dispersion by the ocean dynamics, and sinks (including the life cycle of the plastics themselves, as well as their interactions with biogeochemical cycles into the ocean). If the level of maturity for these different features is high some unknowns are still subject to important research efforts and would be discussed.