25 Nov Microplastic Pollution Found in the Lenga and Tubul-Raqui Estuaries in Biobío
A study by the Millennium Institute SECOS reveals the first evidence of microplastics in estuarine sediments in southern Chile. Although concentrations are low compared to highly industrialized estuaries around the world, scientists interpret this as an “early warning” that calls for preventive action to protect these ecosystems, which are vital for biodiversity and the local economy.
Plastic pollution is one of the greatest global environmental challenges. Millions of tons of waste degrade in the ocean into microplastics—particles smaller than 5 millimeters—that invade every corner of the marine environment, from the water column to bottom sediments. A pioneering study in Chile, published in the journal Environments, confirmed the presence of these particles in sediments from two estuaries in the Biobío region: Lenga and Tubul-Raqui.
The research, led by the Millennium Institute for Coastal Socio-Ecology (SECOS) in collaboration with Universidad Adolfo Ibáñez (UAI) and the University of Concepción (UdeC), sought to fill a critical gap in local science.
According to Dr. Ricardo Barra, SECOS researcher and academic at UdeC’s Faculty of Environmental Sciences, the motivation was clear: “Microplastic research has largely overlooked estuaries—important ecosystems at the interface between land and sea. We wanted to determine whether the intensity of human intervention is reflected in contamination levels in sediments, which represent a longer-term record of pollution. This is the first report of microplastics in estuarine sediments in Chile.”
Two Realities, One Common Problem
The Lenga and Tubul-Raqui estuaries represent contrasting settings. Lenga, located in San Vicente Bay, is highly industrialized, while Tubul-Raqui is dominated by artisanal fisheries. Results reflected this difference: Lenga registered a significantly higher abundance (106.9 particles per kilogram of sediment) compared to Tubul-Raqui (49.3 particles).
The study identified fibers, fragments, foams, and films as the most common types of microplastics. Infrared spectroscopy (FTIR) analysis revealed the chemical “fingerprint” of these polymers, uncovering distinct profiles in each estuary.
Through FTIR spectroscopy, researchers identified the composition of the polymers present. In Lenga, polyamide (PA) predominated, representing 35% of the total, followed by polyester and polyurethane—materials commonly found in technical clothing, fishing nets, and industrial products. In Tubul-Raqui, the most abundant polymer was polyvinyl chloride (PVC), widely used in pipes, packaging, and construction materials.
Low Concentrations: Good News or Warning?
Although concentrations are dozens of times lower than those reported in estuaries in regions such as China, India, or France—where levels can exceed 1,000 particles per kilogram—these differences respond both to industrial development and to local factors such as sediment type, currents, rainfall, and waste management. In this context, researchers agree that this is not good news, but an early warning.
For Barra, who also directs the EULA-UdeC Center, “this represents an early warning. We need to investigate now what effects this contamination has on organisms living in the estuary. The call is to prevent and improve plastic waste management.”
Marco Lardies, academic at UAI and SECOS researcher, adds a layer of urgency: “Although the levels are lower, this study and others show that estuaries in south-central Chile act as reservoirs and seasonal sources of microplastics, with increases of up to 20-fold in winter. This indicates that contamination is still incipient, but there is growing risk if local mitigation measures are not implemented.” He adds that this type of pollution “can directly affect benthic and fishery species through ingestion or habitat alteration. These particles modify sediment structure and essential biogeochemical cycles. Polymers such as PVC and polyamides can release toxic additives and heavy metals, acting as vectors for contaminants throughout the food web.”
An Urgent Call for Prevention
Because microplastics largely originate from the fragmentation of larger plastics, their removal from the environment is practically impossible. For this reason, the authors emphasize the importance of preventing their entry, strengthening waste management, reducing single-use plastics, and promoting new public policies.
“Plastic pollution goes beyond waste management—it is a material with multiple applications, but one that must be designed for a better end-of-life,” says Barra. “We must move toward better use, eliminate non-essential applications, and improve recyclability through design. It is not impossible, but it requires technological and political will.”
Chile has made progress with laws restricting plastic bags and regulating single-use plastics, such as Law 21.368, in addition to the Extended Producer Responsibility (EPR) framework. However, the researchers argue that more specific measures are still needed for coastal ecosystems, where impacts can extend to biodiversity and human health.
“Even in low-industrialization areas like Tubul-Raqui, microplastics are already present and accumulating in sediments,” notes Lardies. “This demonstrates the need to expand environmental monitoring and enforcement, and to incorporate estuarine ecosystems into national waste management and coastal conservation plans, prioritizing prevention over remediation.”