Simulation of the transport of marine microplastic particles in the Ionian Archipelago (NE Ionian Sea) using a Lagrangian model and the control mechanisms affecting their transport.

The Mediterranean Sea is among the most affected areas of our planet by microplastic (MP) pollution. However, some regions are still underrepresented in the current literature. This work studied the fate of microplastics (MPs) released from major populated areas within the NE Ionian Sea, an area that contains highly significant biodiversity. This was accomplished by incorporating oceanographic data into a Lagrangian particle-tracking numerical model that simulated the transport of MP particles for the interval of 27 months. The findings report a high possibility of beaching within the first weeks of the simulation for most locations, where 63 % of MPs were beached and 37 % were still floating at the end of the simulation. Seaward transport and eddy diffusivity are the controlling mechanisms of the MP transport, with diffusion being the primary force controlling the movement of MP particles in 1/3 of the simulated regions. This is highly significant, because in areas where diffusion is the main mechanism controlling MP transport, accumulation of floating MP particles is occurring, as reported in previous studies. The MPs' transport and beaching behavior, as well as the observed residence times, were used to determine the threat level that MPs pose to the biodiversity of specific areas.