Microplastics Beach Pollution: Composition, Quantification and Distribution on the Southern Coast of Brazil

Environmental contamination by plastics poses a significant threat to both fauna and flora, manifesting in lethal and sub-lethal effects. Plastics can enter coastal and marine environments through wind and rain, with microplastics (< 5 mm; MPs) arising from the degradation of larger plastics or being manufactured for commercial use. Despite Brazil's extensive coastline, data on microplastic contamination is scarce. This study aimed to assess microplastic pollution on a beach in Rio Grande do Sul, Brazil. Samples were collected from 30 points along the high tide line, with beach sand processed through density separation and filtration. Microplastics were quantified using Nile Red stain under fluorescence microscopy and chemically identified via the µRaman technique. Results showed an average concentration of 650 MPs/kg of sediment, with higher concentrations near the Mampituba River, indicating a greater transport of plastic contaminants by the river to the coastline. The smallest particles (50–100 µm) were most abundant, and the predominant types of plastics identified were polyethylene (PE), polypropylene (PP), and polyamide (PA). This study provides the first quantification of microplastic pollution in this region, indicating that the concentration and types of microplastics are consistent with findings elsewhere in Brazil and globally. These results highlight the widespread nature of microplastic pollution and underscore the need for coordinated environmental remediation efforts.