Identificação química e quantificação de Microplásticos em sedimentos nas Microbacias da cidade de Manaus

Abstract

Microplastics (MPs) represent a global threat to aquatic ecosystems, with pronounced impacts in urbanized areas such as Manaus, where industrial activities and inadequate plastic waste management exacerbate contamination across environmental matrices. This study investigates the occurrence, morphological characterization, and quantification of MPs in sediments from urban micro-basins in Manaus and from the Negro, Solimões, and Amazon rivers, aiming to address key research gaps in Amazonian freshwater ecosystems. Sediment samples were collected using a Van Veen grab sampler, then dried at 65°C, sieved through a 5 mm mesh, subjected to density separation using ZnCl₂ (1.70 g/cm³), and treated for organic matter oxidation. MPs were morphologically classified into fibers, fragments, pellets, and films via optical microscopy. Estimated MP abundance ranged from 540 to 1,450 particles/kg. Fragment-shaped MPs, particularly white and black in color, were the most prevalent. Polymer composition was identified using FTIR-ATR spectroscopy, with polyethylene (PE) 28%, polypropylene (PP) 26%, and polystyrene (PS) 17% identified as the dominant polymer types. The data obtained in this research demonstrate that the sediments of the urban microbasins of Manaus act as significant reservoirs of microplastics, with a predominance of worn-down nuclei and polymers from everyday use. This confirms the persistence of these substances in the environment.