A Regional Lagrangian Model for Assessing the Dispersion of Floating Macroplastics from Different Source Types over the Iberian Peninsula in the North Atlantic Ocean

Plastic debris in the oceans is a major environmental concern that knows no borders. This material, which is the result of poor waste management on land, is spread across the ocean over long distances and over long periods of time. When macroplastics (those larger than 5 mm) break down through mechanical and chemical processes, they become microplastics. It is difficult to estimate the extent and predict the behavior of these tiny pieces of plastic, but their presence in a variety of organisms, including mollusks and humans, has raised concerns about the potential consequences, which are not yet fully understood but are believed to be significant. To address this problem at a global scale, it is important to identify and quantify the sources of plastic waste that end up in the ocean. We use a validated Lagrangian model (Cloux et al., 2022) to track floating particles coming from potential sources. We studied three types of sources along the Atlantic coast of Spain: rivers, land-based points, and maritime traffic. Over a 7-year period, we analyzed the concentrations of these plastics in the open seas. Our results showed that a significant contribution comes from these sources, both at short and medium distances from the coast. If we consider the fact that some of the simulated particles get washed up on the shore, the concentration of particles near the coast is even higher in certain locations and the concentrations at medium distances are reduced.  Considering semi-enclosed areas, the influence of seasonality was studied for the Bay of Biscay, the Gulf of Cadiz and the Alboran Sea.  The presence of particles in each zone varies between warm and cold seasons, depending on the dynamics of the zone.  The results of this study are under review processes (Cloux et al., n.d.).   Cloux, S., Allen-Perkins, S., de Pablo, H., Garaboa-Paz, D., Montero, P., & Pérez-Muñuzuria, V. (2022). Validation of a Lagrangian model for large-scale macroplastic tracer transport using mussel-peg in NW Spain (Ría de Arousa). Science of The Total Environment, 822, 153338. https://doi.org/10.1016/j.scitotenv.2022.153338 Cloux, S., Pérez-Pérez, P., de Pablo, H., & Pérez-Muñuzuri, V. (n.d.). A Regional Lagrangian Model to Evaluate the Dispersion of Floating Macroplastics in the North Atlantic Ocean from Different Types of Sources in the Iberian Peninsula. Available at SSRN 4306128.