First assessment of microplastic and artificial microfiber contamination in surface waters of the Amazon Continental Shelf.

The composition and distribution of microplastics (MPs) in the Brazilian Amazon Continental Shelf surface waters are described for the first time. The study was conducted during the 2018 rainy and dry seasons, using 57 water samples collected with aluminum buckets and filtered through a 64-μm mesh. The samples were vacuum-filtered in a still-air box, and the content of each filter was measured, counted, and classified. A total of 12,288 floating MPs were retrieved; particles were present at all 57 sampling points. The mean MP abundance was 3593 ± 2264 items·m, with significantly higher values during the rainy season (1500 to 12,967; 4772 ± 2761 items·m) than in the dry season (323 to 5733; 2672 ± 1167 items·m). Polyamides (PA), polyurethane (PU), and acrylonitrile butadiene styrene (ABS) were the most common polymers identified through Fourier Transform Infrared Spectroscopy (FTIR) analysis. Cellulose-based textile fibers were also abundant (~40%). Our results indicate that the Amazon Continental Shelf is contaminated with moderate to high levels of MPs; the highest abundances were recorded at stations near land-based sources such as river mouths and large coastal cities.