The pollution caused by the dumping of plastics, as well as the accumulation of small particles of these products manufactured by humans, has been studied for years in practically all seas and oceans. Unfortunately, microplastics are also spreading through lakes and reservoirs all over the planet, as evidenced by one of the first global studies carried out on this matter, the results of which have now been published in the journal Nature.
“We have found microplastics in all the lakes we have analyzed,” concludes Ted Harris, one of the study authors and an associate research professor at the Kansas Biological Survey.
"Some of the lakes studied are considered clean and beautiful places to spend a vacation, but we found that these places are perfect examples of the link between plastics and humans."
Ted Harris is one of 79 researchers belonging to the Global Lake Ecological Observatories International Network (GLEON), which examines the processes and phenomena that occur in freshwater environments. The now-published paper, titled "Plastic Debris in Lakes and Reservoirs," reveals that concentrations of plastic found in freshwater environments are actually higher than those found in so-called garbage patches or islands of plastics in seas and oceans.
Ted Harris and his collaborator Rebecca Kessler looked specifically at two Kansas lakes (Clinton and Perry) and Cross Reservoir. “Our job consisted of navigating and taking samples with the help of a net with small holes, which we dragged for about two minutes to collect possible residues and deliver them to the researchers specialized in the analysis”, explains Kessler.
The research project was designed and coordinated by the Inland Water Ecology and Management research group at the University of Milano-Bicocca, Italy (led by Barbara Leoni and Veronica Nava). The team sampled the surface waters of 38 lakes and reservoirs, distributed along gradients of geographic position and various limnological attributes. The main conclusion is that significant amounts of plastic debris were detected in all the lakes and reservoirs studied.
“This paper essentially shows that the more humans, the more plastics,” Harris said. “Places like Clinton Lake have relatively low amounts of microplastics because while there are lots of animals and trees, there aren't many humans, compared to a place like the famous Lake Tahoe, which is heavily populated in its immediate vicinity. Some of these lakes appear pristine and beautiful, but microplastic pollution stems from human presence.”
Pollution is due in many cases to plastic spills that fragment and remain in the water, but more scattered phenomena also occur that end up leaving microfibers in the water. "The simple fact that people submerge themselves in water with clothes that have microplastic fibers causes microplastics to reach everywhere," says this co-author of the study in statements released by his university.
The GLEON study cites two types of studied water bodies that are particularly vulnerable to plastic pollution: lakes and reservoirs in densely populated and urbanized areas; and those with elevated deposition areas, long water retention times, and high levels of anthropogenic influence.
“When this paper says 'concentrations as great as or worse than ocean garbage patches or islands,' you always think of the big bottles and stuff, but you're not thinking of all those smaller things. You don't see a huge trash patch in Lake Tahoe, but it is one of the hardest hit lakes when it comes to microplastics. Those are plastics that you can't really see with the naked eye but with a microscope you see these little irregular pieces and other particles that are the same size as algae or even smaller."
“The most important takeaway from our study is that microplastics can be found in all lakes,” Kessler highlights. “Obviously, there are different concentrations. But they are literally everywhere. And the biggest contributing factor to these microplastics is human interaction with the lakes.”
