A new study reveals that concentrations of plastic found in freshwater environments are actually higher than those found in so-called “garbage patches” in the ocean.

Every year, 14 million tons of plastic make their way into the ocean. But that’s not the only source of water where plastic is a big problem.

Ted Harris, associate research professor for the Kansas Biological Survey & Center for Ecological Research at the University of Kansas, remarked, “We found microplastics in every lake we sampled.

“Some of these lakes you think of as clear, beautiful vacation spots. But we discovered such places to be perfect examples of the link between plastics and humans.”

Harris is one of 79 academics that make up the multinational Global Lake Ecological Observatory Network (GLEON), which studies freshwater processes and occurrences.

Their most recent study, published in Nature, demonstrates that freshwater habitats have larger quantities of plastic than do so-called “garbage patches” in the ocean.

Harris’s job was to test two Kansas lakes (Clinton and Perry) and the Cross Reservoir at the KU Field Station with Rebecca Kessler, one of his past students and a new KU graduate.

“That entailed us going out, tolling a net with tiny little holes in it, dragging it for about two minutes, then collecting those samples of microplastics and sending them off to (the lead researchers),” Kessler added.

Barbara Leoni and Veronica Nava of the University of Milano-Bicocca, Italy’s Inland Water Ecology and Management research group planned and oversaw the study’s execution. The researchers took surface water samples from 38 lakes and reservoirs that were spread out along gradients of limnological characteristics and geographic location. It found pieces of plastic in all of the lakes and ponds it looked at.

“This paper essentially shows the more humans, the more plastics,” Harris added. “Places like Clinton Lake are relatively low in microplastics because — while there are many animals and trees — there aren’t a lot of humans, relative to somewhere like Lake Tahoe where people are living all around it. Some of these lakes are seemingly pristine and beautiful, yet that’s where the microplastics come from.”

According to Harris, many of the plastics come from seemingly harmless items like T-shirts.

“The simple act of people getting in swimming and having clothing that has microplastic fibers in it leads to microplastics getting everywhere,” he added.

According to the GLEON research, lakes and reservoirs in highly inhabited and urbanized regions as well as those with higher deposition areas, lengthy water retention durations, and high levels of human impact are especially prone to plastic pollution.

“When we started the study, I didn’t know a lot about microplastics versus large plastics,” Harris added.

“When this paper says ‘concentrations as much or worse than the garbage patch,’ you always think of the big bottles and stuff, but you’re not thinking of all that smaller stuff. You don’t see a huge garbage patch in Lake Tahoe, yet it’s one of the most impacted lakes when it comes to microplastics. Those are plastics you can’t really see with the naked eye, and then you get underneath a scope at 40,000x, and you see these little jagged pieces and other particles that are the same size as algae or even smaller.”

The goal of this initiative was in part for Harris and Kessler to draw attention to a section of the United States that is often ignored.

“In this study, there’s one dot in the middle of the country, and that’s our sample,” he added. “In Iowa, Missouri and Colorado, there’s this huge swath of area that has water bodies, but we often don’t get them into those massive global studies. So it was really important for me to put Kansas on the map to see and contextualize what these differences are in our lakes.”

Since 2013, Harris has been employed at KU, where he does aquatic ecology-related research. Kessler earned a degree in ecological, evolutionary, and organismal biology from KU in 2022.

“The biggest takeaway from our study is that microplastics can be found in all lakes,” Kessler added. “Obviously, there are different concentrations. But they are literally everywhere. And the biggest contributing factor to these microplastics is human interaction with the lakes.”

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