Microplastic Pollution in Water and Sediments in a Public Supply Reservoir in Presidente Prudente (SP), Brazil

Abstract Herein, we investigate the occurrence, distribution, polymer composition, and abundance of microplastics in water and sediment samples collected from the Sabesp reservoir in Presidente Prudente, São Paulo State, Brazil, a major source of public water supply. Sampling was conducted at six points during three distinct campaigns to assess seasonal and spatial variations. A total of 663 microplastic particles were identified (636 in water and 27 in sediment), predominantly fibers (78% in water and 48% in sediment). The main polymers identified by micro-Raman spectroscopy were PET, PP, PES, PE, and iPP, along with fibers showing spectral signatures of indigo dye. Higher microplastic concentrations were observed near the spillway, likely influenced by hydrological flow dynamics and proximity to urbanized areas, suggesting that untreated domestic and industrial effluents are the primary sources of contamination. Based on the reservoir volume and sample data, the total estimated microplastic load was approximately 15.7 million particles. The persistence of these materials, combined with their potential to adsorb other pollutants, poses significant environmental and human health risks. These findings underscore the need for continuous water-quality monitoring, improved waste management, and effective public policies aimed at reducing plastic inputs into aquatic environments, contributing to the global effort to mitigate microplastic pollution.