Modeling Coastal and Offshore Marine Litter Accumulation in the Irish Seas

Concern about the problem of marine debris has grown in recent years, as it is now known to be a large-scale problem affecting everything from coastal environments to the open sea [1]. Therefore, understanding how these pollutants move and are transported is key to developing containment and prevention policies but also management strategies. Due to its specific location, Ireland poses a challenge in terms of transport, as it has complex circulation patterns that interact with multiple land inputs. That is why numerical modelling is a valuable tool for assessing the transport and fate of marine debris at different spatial scales.

In this study, a Lagrangian modeling approach is applied to the Irish Sea to estimate marine litter concentrations in both coastal areas and offshore waters. Rivers are assumed to be the main terrestrial sources of waste, with contributions from the main Irish rivers estimated and weighted according to demographic and socioeconomic factors, such as population size and a deprivation index associated with each river basin. The aim is to obtain a more realistic view of anthropogenic pressure on the marine environment.

Particle tracking simulations were performed using the Lagrangian MOHID model [2], a powerful tool for simulating the transport and dispersion of passive tracers in the marine environment. In this case, 3D simulations of the trajectories of virtual particles representing marine debris will be taken into account. This approach allows for the identification of both accumulation and barrier zones, providing solid support for empirical data-based marine debris management and mitigation strategies.

[1] Rangel-Buitrago, N., Williams, A., Costa, M. F., & de Jonge, V. (2020). Curbing the inexorable rising in marine litter: An overview. Ocean & Coastal Management, 188, 105133.

[2] Cloux, S., Allen-Perkins, S., de Pablo, H., Garaboa-Paz, D., Montero, P., & Muñuzuri, V. P. (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.