27 MARCH 2024.
JAPAN WOMEN'S UNIVERSITY
PUBLIC RELATIONS DIVISION,

PRESS RELEASEWorld's first demonstration that forests trap
airborne microplastics

A research group led by Japan Women’s University finds that airborne microplastics adsorb
to the epicuticular wax on the surface of forest canopy leaves, and that forests may act as
terrestrial sinks for airborne microplastics
Tokyo, Japan – Think of microplastics, and you might think of the ones accumulating in theworld’s oceans. However, they are also filling the sky and the air we breathe. Now, it has beendiscovered that forests might be acting as a sink for these airborne microplastics, offering
humanity yet another crucial service.

Polyethylene

Airborne microplastics

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cm-1

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記述

Polypropylene

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9590

Forest filter effect

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名前Forest
Canopy

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AMPs supplementation
mechanism by leaves
Ø Physical capture by trichomes
Ø Adsorption with epicuticular wax
Adaxial side

Epicuticular wax
Trichomes
Abaxial side

Dynamics of AMPs in the forestarea.

27 MARCH 2024.
JAPAN WOMEN'S UNIVERSITY
PUBLIC RELATIONS DIVISION,

PRESS RELEASE

In a recently published study, a multi-institutional research group led by Professor Miyazaki Akane
of Japan Women’s University has used a new technique to measure the levels of microplastics
adhering to the leaves of trees, revealing that forests are potentially acting as terrestrial sinks forthese particles.
Microplastics have come into public focus within the last decade because of their effects on theenvironment and human health. Airborne microplastics are tiny plastic particulates(less than 100 µm) that become suspended in the atmosphere and dispersed throughout theenvironment, but it has been unclear where they end up. Forests have been known to accumulate
airborne pollutants, but their ability to capture airborne microplastics has been poorly understood.
“We investigated airborne microplastics on konara oak tree leaves in a small forest in Tokyo,” says
lead author of the study, Natsu Sunaga. “We wanted to determine a reliable method for analyzing
levels of these microplastics on leaf surfaces, and how exactly airborne microplastics becometrapped by leaves.”
The team examined the leaves of Quercus serrata, a species of oak representative of Japanese
forests. To extract the plastics, the leaves were treated using three processes: washing withultrapure water, simultaneous treatment with ultrasonic waves and washing with ultrapure water,and treatment with an alkaline solution of 10% potassium hydroxide.
“We found that airborne microplastics strongly adsorb to the epicuticular wax on the leaf surface,”
explains Akane Miyazaki, senior author. “In other words, these particles accumulate when they
stick to the waxy surface coating of leaves.”
The team discovered that the first two treatments – rinsing with ultrapure water alone or in
combination with ultrasonic waves – were insufficient for accurately determining the levels ofairborne microplastics on forest canopy leaves. Treatment with alkaline potassium hydroxide,
however, removed both the epicuticular wax and the substances adhered to it, proving to be aneffective method for detecting airborne microplastics stuck to leaf surfaces. Crucially, previousstudies that used only the first two methods may have underestimated the number of plastics
adhering to leaf surfaces.
“Based on our findings, we estimate that the Quercus serrata forests of Japan (~32,500 km2) trap
approximately 420 trillion airborne microplastics per year in their canopies,” states Sunaga. “Thisindicates that forests may act as terrestrial sinks for airborne microplastics.”
How the accumulation of these microplastics will affect forest ecosystems, including ecosystem
functions and soil health, is unknown, and this will undoubtedly be an area of further research. For
now, we know that forests and even roadside canopies might reduce the amount of plastic entering
our lungs, and for that we have yet another reason to thank trees.
###27 MARCH 2024.
JAPAN WOMEN'S UNIVERSITY
PUBLIC RELATIONS DIVISION,

PRESS RELEASE

Reference
Title of original paper : “Alkaline extraction yields a higher number of microplastics in forest canopy
leaves: implication for microplastic storage”
DOI : 10.1007/s10311-024-01725-3
Journal : Environmental Chemistry Letters
Article Publication Date : 20 March 2024
Authors : Natsu Sunaga a, Hiroshi Okochi b, Yasuhiro Niida c, Akane Miyazaki a,＊a Graduate School of Chemical and Biological Sciences, Japan Women's Universityb Graduate School of Creative Science and Engineering, Waseda Universityc PerkinElmer Japan G.K.
＊Corresponding author. Akane Miyazaki

Japan Women's University was founded as Japan's first organized institution of higher education for women,and celebrates its 120th anniversary in 2021. It is the only private women's university with a Faculty ofscience, and is a women's comprehensive university with an educational environment that integrates thehumanities and sciences. The Faculty of Transcultural Studies opened last year, and new faculties arescheduled to open in 2024 (Faculty of Architecture and Design) and 2025 (Faculty of Food Science (tentativename, under planning)). Under the tagline of "I move, and the world opens up," we are fostering humanresources who can learn and act on their own initiative and create new value. For more information, please
visit https://www.jwu.ac.jp.

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