February 4, 2023

The impact of plastic pollution in lakes is less well researched than in the oceans.

Chemicals leaching from plastic waste cause bacteria to grow faster in European lakes, according to research published Tuesday that the authors said could be a natural way to remove plastic pollution from freshwater ecosystems.

Microplastics have been found in virtually every corner of the world – from the highest glaciers to the bottom of the deepest sea channel – but the impact of plastic pollution in lakes has been less well studied than in oceans.

When plastic materials such as carrier bags break down in water, simple carbon compounds are released that are slightly different from those produced when organic matter such as twigs and leaves decompose.

Researchers from the University of Cambridge wanted to see what effect these compounds had on bacterial populations in 29 lakes in Scandinavia.

They cut up plastic bags from four major British retail chains and mixed them with water until the carbon compounds were released.

They then filled glass bottles with water from each lake and mixed a small amount of the plastic water into half of these samples.

In the water containing plastic-derived compounds, the bacteria had doubled in mass within 72 hours and had already absorbed about half of the carbon in the samples.

Overall, they found that the bacteria in the plastic water samples grew almost twice as easily (1.72 times) as the bacteria in the lake without the addition of plastic water.

Andrew Tanentzap, of the Department of Plant Sciences at the University of Cambridge, said the study showed that the major impact of plastic pollution is likely on freshwater bodies where the waste is present.

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“It’s almost as if the plastic pollution is triggering the bacteria’s appetite,” he said.

“This suggests that plastic pollution drives the entire food web in lakes, because more bacteria means more food for the larger organisms such as ducks and fish.”

The study examined how bacteria respond to plastic carbon compounds in lakes of varying depths, locations, surface temperatures and organic matter content.

It showed that bacteria were better at removing plastic pollution in lakes with fewer unique natural carbon compounds because there were fewer natural food sources.

The results suggested that in some places specific types of bacteria could be used to break down plastic waste.

“But you would want to know more about the balance of the ecosystem before you do that,” study lead author Eleanor Sheridan told AFP.

She also warned against assuming that bacteria alone could solve the growing ecological disaster caused by plastic waste.

Plastics “not only harm ecosystems on a macro level, they also contain chemicals that leach out and last longer when a plastic bag is fished out of the water,” Sheridan said.

“I hope this raises awareness of the multitude of different effects that just one type of pollution can have on the environment.”

Natural cleanup: Bacteria can clear plastic pollution from lakes

More information:
Eleanor Sheridan, Plastic pollution promotes more microbial growth in lakes than natural organic matter, nature communication (2022). DOI: 10.1038/s41467-022-31691-9. www.nature.com/articles/s41467-022-31691-9

© 2022 AFP