A research group led by Japan Women's University has revealed that forests can capture airborne microplastics, potentially reducing human health risks. This groundbreaking discovery reaffirms the importance of forest conservation and management, providing a new perspective in environmental conservation and public health.
The study conducted by the research group centered at Japan Women's University has become a new milestone in the fields of environmental protection and public health. The research revealed that microplastics, tiny plastic particles floating in the air, are adsorbed by the waxy layer called epicuticular wax on the surface of tree leaves. This suggests that forests have the potential to purify the air around us and reduce the risk of human inhalation of microplastics.
What are Microplastics?
Microplastics are small plastic fragments less than 5 millimeters in diameter, with those smaller than 100 micrometers (μm) being particularly prone to becoming airborne. These particles are generated from various daily activities such as washing clothes, using cosmetics, and the degradation of plastic products. Once released into the environment, they spread into the oceans, land, and air, potentially harming ecosystems and human health.
Research Background
Previous studies primarily focused on the accumulation of microplastics in aquatic environments such as oceans and rivers. However, recent studies have pointed out that microplastics also exist in the air people breathe daily, which is one of the main routes of intake into the human body. This increased awareness of airborne microplastics and the need for their management, but little was known about the specific capture mechanisms and the role of nature in reducing them.
Research Content and Findings
This study focused on a forested area located on the Nishi-Ikuta campus of Japan Women's University, mainly collecting leaves from konara oak trees. The research team developed a new method to analyze the microplastics trapped on the leaf surfaces and investigated the extent to which microplastics are adsorbed by the epicuticular wax.
The results showed that microplastics strongly adhere to the epicuticular wax and cannot be sufficiently removed by conventional cleaning methods. This suggests that forests have the potential to function as effective sinks (absorption sources) for capturing airborne microplastics. It also revealed that through this mechanism, forests play a new and important role in reducing the risk of human inhalation of microplastics.
Social Significance and Future Challenges
This discovery suggests that forests in urban areas and their surroundings, as well as trees in streets and parks, can play an important role in measures against atmospheric microplastic pollution. It demonstrates that the approach of bioremediation, solving environmental problems using biological methods, can also be effective in tackling the microplastic issue.
However, it is also pointed out that the microplastics captured by forests may fall to the ground with fallen leaves, accumulate in soil and water systems, and ultimately destroy forest ecosystems. Therefore, it is necessary to develop a comprehensive strategy to better understand the impact of microplastics on the environment and manage them.
Microplastic Capture Capacity of Forests
This study showed that the ability of forests to capture airborne microplastics is due to the waxy layer called epicuticular wax on the surface of tree leaves. Epicuticular wax is a special structure developed by plants to protect themselves from the external environment, preventing excessive evaporation of moisture and blocking the invasion of harmful substances. The study revealed that epicuticular wax can physically adsorb microplastic particles and remove them from the air.
Microplastic Issues and Forest Conservation
The issue of microplastics has rapidly gained recognition as one of the global environmental problems in recent years. It has become known that microplastics spread not only in the oceans but also on land and in the air, raising concerns about their potential impact on health. The discovery that forests can capture airborne microplastics suggests that forest conservation is important not only for protecting biodiversity but also for safeguarding human health. Therefore, protecting and properly managing forests becomes an important strategy for both environmental conservation and public health.
During a recent visit to the forest for maintenance, I witnessed the beautiful scenery of cherry and pine trees, which can be considered the original landscape of Japan. Mie Prefecture has a forest area of approximately 65% of its total land area, making it one of the leading forest prefectures in Japan, nurturing a diverse ecosystem.
The mixed arrangement of coniferous and broad-leaved forests is particularly characteristic. There are diverse forests such as red pine forests, red pine-konara oak forests, and beech forests.
Each forest is home to unique living creatures. For example, the Japanese squirrel inhabits the red pine-konara oak forest. A rich ecosystem is being nurtured. The leaves of the forest also play a role in capturing microplastics drifting in the air, protecting our health.
As the importance of forest management further increases, appropriate thinning and undergrowth clearing to cultivate healthy forests will contribute to both biodiversity conservation and microplastic countermeasures.
Bioremediation through Forests
Another important aspect suggested by this research is the possibility of bioremediation using forests, that is, environmental purification using living organisms. Since forests in and around urban areas, as well as street trees and park trees, can function as natural purification systems for air pollutants, it is required to actively incorporate these natural purification systems into environmental protection policies and urban planning.
While this discovery has clarified the specific mechanism by which forests capture airborne microplastics, further research is needed. For example, comparing the capture efficiency of different tree species and under various environmental conditions, investigating the impact of captured microplastics on forest ecosystems, and developing safe methods for treating captured microplastics are mentioned. In addition to forests, the development of new microplastic capture systems such as urban green spaces and rooftop greening is also considered an important research field.
This research, which revealed the ability of forests to capture airborne microplastics, has very important implications from the perspective of environmental conservation and public health. It can be said that a new strategy for realizing a healthier and more sustainable environment through forest conservation and proper management has been shown. With further research and technological advancements, we can expect to deepen our coexistence with nature and find more effective solutions to global environmental problems.
Arne Naess stated, "Through deep ecological understanding, we can build a harmonious relationship with nature." This research teaches us once again the importance of understanding the wondrous power of nature and harnessing it for the welfare of humanity. Each of us thinking about what we can do for nature conservation and taking action will be the first step toward a better future.
References and Sources
The results of this study were published in the journal "Environmental Chemistry Letters." The title of the paper is "Alkaline extraction yields a higher number of microplastics in forest canopy leaves: implication for microplastic storage."
This research was conducted by a research group consisting of Professor Akane Miyazaki of the Graduate School of Science at Japan Women's University, Natsuki Sunaga, a master's student in the Graduate School of Science at the same university, Professor Hiroshi Okouchi of the Faculty of Science and Engineering at Waseda University, and Yasuhiro Niida of PerkinElmer Japan Co., Ltd.
Paper publication URL: https://doi.org/10.1007/s10311-024-01725-3