Microplastics in sediment samples from the mouth of the Amazon River

In Brazil, there are few studies about the presence of microplastics (MPs) in continental aquatic environments, with a notable gap in water and sediment samples from the mouth of the Amazon River. A previous study conducted in the North Equatorial Current indicated that the highest concentration of certain plastic additives is precisely in the Amazon plume zone in the North Atlantic. Therefore, our objective was to detect and characterize the MPs in sediment samples from the mouth of the Amazon River. Ten samples (seven in the North Channel and three in the South Channel) were collected in October/2021. The MPs were characterized according to their morphometric (size, volume, specific surface area, color, and shape) and chemical properties (µFTIR and µRaman). Sample processing and analysis followed the methods recommended in the literature and quality control protocols. The quantity of MPs varied from 99 ± 28 to 894 ± 147 particles/100 g dry weight (dw) sediment, with considerable differences in terms of their morphological dimensions and chemical composition. Considering the samples from each channel together, the average volumes of MPs in the North and South Channel were, respectively, 0.159 ± 0.082 and 0.229 ± 0.190 mm³/100 g dw sediment. The average specific surface areas were 33.8 ± 19.8 and 50.4 ± 23.3 mm²/100 g dw sediment in the North and South Channel, respectively. About 84 Also see: https://micro2024.sciencesconf.org/558324/document