Faster growth may help bacteria remove plastic waste from lake: study

Published on:

Paris (AFP)- Chemicals leaching from plastic waste are accelerating the growth of bacteria in European lakes, according to a study published on Tuesday which the authors believe could provide a natural way to remove plastic pollution from freshwater ecosystems.

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

When plastics such as carrier bags break down in water, they release simple carbon compounds that are slightly different from those produced when organic materials such as twigs and leaves break down.

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

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

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

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

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

Andrew Tanentzap, from the University of Cambridge’s Department of Plant Science, said the study showed the profound impact of plastic pollution on freshwater bodies where litter is present.

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

“This suggests that plastic pollution stimulates the entire food chain in lakes, as more bacteria means more food for larger organisms like ducks and fish.”

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

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

The results suggest that in some places, specific types of bacteria could be harnessed to help break down plastic waste.

“But you would want to know more about the balance of the ecosystem before you commit to it,” Eleanor Sheridan, first author of the study, told AFP.

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

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

“I hope this will increase awareness of the multitude of different effects that a single type of pollution can have on the environment.”

Bryce K. Locke