Plastic pollution is a major challenge of our time. Researchers have mostly studied plastic impacts in marine environments, leaving the role of freshwater ecosystems, like lakes and reservoirs, overlooked in global plastic pathways.
Veronica Nava, University of Milano-Bicocca, Milan, Italy, and colleagues have conducted a standardized cross-national survey to assesses the abundance and type of plastic debris in freshwater ecosystems. They collected surface water samples from 38 lakes and reservoirs, ensuring representation of various lake types based on size, depth, population density, and degree of sealing of the surrounding land. The researchers filtered an average of 140 m3 of lake water per site and focused on counting microplastic particles larger than 0.25 mm. As this study was a snapshot, it did not consider temporal and spatial variations in microplastic occurrence.
The team discovered plastic debris in all of the lakes and reservoirs they studied, indicating a significant role of these ecosystems in the plastic pollution cycle. The plastics identified were mainly polyester, polypropylene, and polyethylene. Plastic concentrations varied widely among the lakes, ranging from 0.01 to over 10 particles/m3. Of the lakes studied, 45 % had more than one particle/m3. Even remote areas, such as Lake Tahoe in the Sierra Nevada, USA, and mountain lakes, contained microplastics. Hence, no lake can be considered truly ‘pristine’ with regards to plastic pollution, even in areas far from direct human impact
In the most polluted lakes, concentrations matched or even exceeded those reported in subtropical oceanic gyres, which are marine areas known for collecting large amounts of debris. Among the lakes with the highest microplastic pollution are some used as sources of drinking water, such as Lake Maggiore (Italy), Lake Lugano (Switzerland-Italy), Lake Tahoe (USA), and Lake Neagh (UK).
The findings suggest that two types of lakes are particularly vulnerable to plastic contamination. The first includes lakes and reservoirs in densely populated and urbanized areas, while the second consists of large lakes and reservoirs with elevated deposition areas, long water-retention times, and high levels of human influence.
The findings add a new stressor to the lakes and the organisms living within them, which are already facing various pressures like climate change, salinization, increased nutrient deposition, and nearshore filamentous algal blooms, among others. These results demonstrate the global extent of plastic pollution and serve as a reminder of humanity’s lasting impact on lakes. They underscore the significance of including lakes and reservoirs in efforts to address and manage plastic pollution.
- Plastic debris in lakes and reservoirs,
Veronica Nava, Sudeep Chandra, Julian Aherne, María B. Alfonso, Ana M. Antão-Geraldes, Katrin Attermeyer, Roberto Bao, Mireia Bartrons, Stella A. Berger, Marcin Biernaczyk, Raphael Bissen, Justin D. Brookes, David Brown, Miguel Cañedo-Argüelles, Moisés Canle, Camilla Capelli, Rafael Carballeira, José Luis Cereijo, Sakonvan Chawchai, Søren T. Christensen, Kirsten S. Christoffersen, Elvira de Eyto, Jorge Delgado, Tyler N. Dornan, Jonathan P. Doubek, Julia Dusaucy, Oxana Erina, Zeynep Ersoy, Heidrun Feuchtmayr, Maria Luce Frezzotti, Silvia Galafassi, David Gateuille, Vitor Gonçalves, Hans-Peter Grossart, David P. Hamilton, Ted D. Harris, Külli Kangur, Gökben Başaran Kankılıç, Rebecca Kessler, Christine Kiel, Edward M. Krynak, Àngels Leiva-Presa, Fabio Lepori, Miguel G. Matias, Shin-ichiro S. Matsuzaki, Yvonne McElarney, Beata Messyasz, Mark Mitchell, Musa C. Mlambo, Samuel N. Motitsoe, Sarma Nandini, Valentina Orlandi, Caroline Owens, Deniz Özkundakci, Solvig Pinnow, Agnieszka Pociecha, Pedro Miguel Raposeiro, Eva-Ingrid Rõõm, Federica Rotta, Nico Salmaso, S. S. S. Sarma, Davide Sartirana, Facundo Scordo, Claver Sibomana, Daniel Siewert, Katarzyna Stepanowska, Ülkü Nihan Tavşanoğlu, Maria Tereshina, James Thompson, Monica Tolotti, Amanda Valois, Piet Verburg, Brittany Welsh, Brian Wesolek, Gesa A. Weyhenmeyer, Naicheng Wu, Edyta Zawisza, Lauren Zink, Barbara Leoni,
Nature 2023, 619, 317–322.