Abstract

Human activities have triggered microplastic pollution, and estuaries have emerged as critical yet understudied ecosystems in Chile. This study investigated sediment microplastic pollution in the Lenga (highly industrialized) and Tubul-Raqui (fisheries village) ecosystems, characterized by contrasting anthropogenic impacts, in the Biobío Region, Chile. Microplastic particles, including fibers, foam, fragments, and film, were detected in both estuaries. The Lenga estuary, heavily industrialized, exhibited a significantly higher total abundance of microplastics compared to the Tubul-Raqui estuary. However, the mean concentrations of microplastics in the studied estuaries are notably lower than those reported in other global studies, aligning more closely with levels found in less polluted estuaries around the world. FTIR analyses identified six types of polymers in Lenga, with polyamide (PA) being the most prevalent, constituting 35% of all polymers detected. Conversely, in Tubul-Raqui, polyvinyl chloride (PVC) emerged as the predominant polymer, comprising 25% of the total. Furthermore, significant correlations were observed with sediment physico-chemical parameters, such as organic matter and pH. These findings confirm the existence of microplastic pollution in both estuaries, highlighting the necessity of continued monitoring and assessment of potential environmental impacts in these ecologically valuable ecosystems. © 2025 by the authors.