Assessment of plastic material dispersion along the coastal region adjacent to Rio de Janeiro - RJ

The increasing global production and improper disposal of plastic waste, particularly microplastics, have raised significant environmental concerns, especially in marine and estuarine ecosystems. The coastal region of the city of Rio de Janeiro, Brazil, is exposed to high levels of microplastic contamination from both terrestrial and marine sources, in addition to other types of pollutants. This study represents the first scientific paper to apply numerical modeling to assess microplastic dispersion in the coastal region adjacent to Rio de Janeiro - RJ. By means of the modeling SisBaHiA - Environmental Hydrodynamics Base System, hydrodynamic and lagrangian transport models were applied, considering typical summer and winter scenarios. The results indicate that, during the modeled periods, coastal currents predominantly flow westward, suggesting longer periods of fair-weather conditions. Lightweight microplastics are strongly influenced by wind forcing, resulting in greater dispersion, whereas neutral and dense microplastics are mainly transported by mid-water and near-bottom currents, respectively, exhibiting moderate and low dispersion patterns, mostly towards the west.