For the first time plastics have been assessed in lakes across the world in a new study published in Nature, with some worse impacted than oceans.
The study shows that plastic fragments and fibres from washing clothes and packaging residues in freshwater lakes and reservoirs are higher than those in plastic islands in the ocean - the so-called plastic 'Garbage patches'.
"Plastics and microplastics affect lakes and reservoirs on a global scale, including the most remote lakes", said co-author Professor David Hamilton, Director of Griffith University's Australian Rivers Institute.
"In addition to negatively impacting drinking water, plastics pollution has harmful effects on aquatic organisms and ecosystem function. Plastics don't break down, they mostly break up into smaller and smaller particles, with increasing potential to be absorbed by living organisms, including humans."
The research was coordinated through the Global Lake Ecological Observatory Network (GLEON), an international consortium of researchers known for investigating global scale processes and phenomena occurring in freshwater environments, of which Professor Hamilton was one of the founding members.
The research used plankton nets to sample the plastic debris in 38 lakes located in 23 different countries. The samples were analysed at the University of Milan-Bicocca, using Raman micro-spectroscopy to accurately determine the polymeric composition of microplastics.
Lakes with the highest contamination of plastic debris are some of the main sources of drinking water for local populations, and included Lakes Maggiore (Italy), Lugano (Switzerland/Italy), Tahoe (US) and Neagh (UK). Lakes in Australia showed moderate levels of plastics contamination.
"Lakes act as 'pollution sentinels', because they integrate and accumulate microplastics arising from the atmosphere and land," said Professor Hamilton
"Plastics that accumulate on the surface of aquatic systems can promote the release of methane and other greenhouse gases," explains Veronica Nava, a research fellow at the University of Milan-Bicocca's Department of Earth and Environmental Sciences, under the supervision of Professor Barbara Leoni, coordinator of the Inland Water Ecology and Management research group.
"Plastics can reach beyond the hydrosphere and interact with the atmosphere, biosphere and lithosphere, potentially affecting biogeochemical cycles."
"Additionally, these environments can retain, modify, and transport plastic debris across watersheds to the oceans," Ms Nava concludes.
"These results demonstrate the global scale of plastic pollution. No lake, not even those furthest from anthropogenic activity, can be considered truly pristine. This should prompt us to review pollution reduction strategies and waste management processes."
