Microplastics in Brazilian rivers: An overview and a study of floating particle accumulation on the coast of Santa Catarina state

Microplastics (MPs; < 5 mm) are a well-established environmental problem. Thus, this study aimed to address critical gaps related to MP in Brazilian rivers through a systematic review and mathematical modeling to assess the dispersion and accumulation zones of floating particles along the Santa Catarina state coast. 35 studies were reviewed, considering water, sediment, and biota. Sinos River, Rio Grande do Sul state, had the highest concentration of MPs in water (> 330 × 10 items/m). Most studies reported a variation between 1 and 100 items/m in water. In sediments, the Tietê River, São Paulo state, had the highest level (∼190 × 10 items/kg). Blue fibers and PE and PP polymers were the predominant characteristics. Fish were the most studied organisms, but freshwater shrimp and stingrays also had MPs internally. The application of Lagrangian tracers and hydrodynamic model, considering four river sources, revealed that floating MPs tend to accumulate in the central-north region of the Santa Catarina coast. Due to oceanographic conditions and river flow, the Itajaí-Açu River can influence the spatial distribution of MPs along the entire coast. Rivers can generate critical accumulation points near their mouths. Thus, these results offer important insights to be considered in combating MPs pollution, from river to marine environments.