Assessing anthropogenic microfiber pollution in the southwestern Atlantic Ocean: a large-scale study on spatial distribution, concentration, and physical characterization.

This study presents the first large-scale assessment of anthropogenic microfiber (AMF) pollution in surface waters (~ 5-m depth) of the Southwestern Atlantic Ocean (SWAO), covering an extensive area of approximately 1.2 million km², spanning coastal, shelf, and shelf-break regions, in a latitudinal range from 34°S to 56°S. A total of 102 water samples were collected during seven fisheries and environmental research cruises, targeting key fishing grounds and Marine Protected Areas. AMFs were found to be ubiquitous throughout the region, with the highest concentrations detected in estuarine zones adjacent to major urban centers. Remarkably, additional hotspots were identified in offshore and remote shelf-break areas, indicating the role of long-range transport and oceanographic retention processes in their accumulation. Evidence of environmental weathering-such as discoloration, fraying, and biofouling-was more prevalent at offshore sites, supporting the hypothesis of prolonged residence and dispersal within the marine environment. AMFs displayed considerable variability in shape, color, and size, with many exhibiting morphological traits typical of textile-derived materials. Given the potential ecological risks, this study highlights the importance of addressing AMF pollution in ecologically productive marine areas, where interactions with marine organisms are more likely.