MARE Researchers Find Widespread Presence of Microplastics in the Mondego and Vouga Rivers

A recent study led by Seena Sahadevan is among the first integrated ecological risk assessments of suspended microplastics in the Mondego and Vouga rivers. As two of the main river systems in the Centre of Portugal region, these findings have direct implications for the conservation of the country's freshwater ecosystems.

Published in the Journal of Hazardous Materials: Plastics, the study analysed suspended microplastics in the water column (between 5 and 15 cm depth) of both rivers, with records across all 14 sampling sites. The findings confirm that microplastic pollution is widespread even in inland freshwater ecosystems, a particularly concerning result given the limited number of studies on these ecosystems compared to marine ones.

The research also identified variations in contamination levels associated with different human pressures, such as urban activities, tourism, agriculture, and infrastructure.

The detected particles were smaller than one millimetre and were mostly composed of fibres. The most frequently found polymers were polyethylene and polypropylene, both widely used in single-use plastic packaging.

The study also conducted a risk assessment based on pollution indices, polymer hazard profiles, and ecological risk potential. The results revealed that several sampling sites fall within risk levels ranging from low to high, primarily due to the presence of small particles that are more easily ingested and transported by aquatic organisms.

This work is the result of a collaboration between the University of Coimbra and the Indian Institute for Science Education and Research Kolkata. The study was led by Seena Sahadevan, a researcher at MARE | ARNET and the Department of Life Sciences at the University of Coimbra, with Sarra Ben Tanfous as first author, alongside contributions from Abhishek Mandal, Juliana Barros, and Gopala Krishna Darbha.

Sahadevan highlights that "this work provides important baseline information on microplastic contamination in freshwater systems in Portugal and underlines the need for continuous monitoring and mitigation strategies".

Text: Patrícia Chaves

Photos: Universidade de Coimbra and Canva