plastic

We constantly hear and read about microplastics and the dangers they pose to our health. However, we have primarily associated them with the seas and oceans where they accumulate in huge quantities. We forget, however, that the microplastic particles that come from the breakdown of the multitude of plastic products that overwhelm our lives also “fly” into the air we breathe – with all that this implies for the health of our respiratory system and beyond.

Microplastics of… adhesion

Now a new Japanese study shows that we have another very good reason to thank forests for their services: because, as this study published in the journal Environmental Chemistry Letters has shown, forests they act as “collectors” of microplastics as the dangerous microparticles cling to the leaves of the trees.

The new technique

The researchers of different Japanese academic centers, led by Prof Akane Miyazaki from Japan Women’s University, used a new technique to measure the levels of microplastics attached to tree leaves. It is noted that microplastics found in the air are plastic particles (less than 100 μm in diameter) that are released into the atmosphere and dispersed in the environment. However, until today it was unclear where they end up. It is known that forests accumulate gaseous pollutants, but also no one knew until now if they have the ability to “collect” suspended microplastics by cleaning the air.

The Japanese oak in the forest of Tokyo

The research team studied the possible presence of microplastics in the leaves of an oak species representative of Japanese forests (Quercus serrata). The research was conducted on trees in a small forest in Tokyo. “We wanted to find a reliable method of analyzing the levels of microplastics on the surface of tree leaves and determine exactly how suspended microplastics are trapped in the leaves,” explained the first author of the new study, Natsu Sunaga.

The three processes of… cleaning

To isolate the microplastics from the leaves, three different procedures were followed by the researchers: washing with distilled water, simultaneous use of ultrasonic waves and washing with distilled water, and finally treatment with an alkaline solution containing 10% potassium hydroxide.

Accumulation on leaves

“We discovered that suspended microplastics are absorbed by the waxy surface of tree leaves,” explained Dr. Miyazaki, who was the lead author of the study, adding that “in other words, these particles accumulate in the leaves.”

Green “trap” of trillions of microplastics

The researchers found that of the three ways of treating the leaves, only the use of potassium hydroxide managed to remove both the wax from the surface of the trees and the substances that had been absorbed by it. “Based on our findings, we estimate that Japan’s Quercus serrata forests (covering an area of ​​about 32,500 km2) trap about 420 trillion airborne microplastics annually,” said Dr. Sunaga. “This shows that forests act as terrestrial collectors of airborne microplastics.”

The unknown future of forest ecosystems

How, of course, the accumulation of microplastics will affect forest ecosystems remains unknown and must be the subject of further research, the researchers stressed. For now, however, we now know from the new study that forests, even roadside kennels, reduce the amount of microplastics that reach our lungs and from there throughout our bodies, giving us another reason to we say a big… green thank you to them.