Plastic is ubiquitous, and humans produce more than 8 billion tons of plastic, but less than 10 percent is recycled. Because plastic waste does not easily break down, it can exist in the environment for hundreds of years, getting smaller and smaller, and eventually end up in our food, our bodies, and the environment.
It’s still unclear exactly how harmful these small particles are to humans, but some of the chemicals found in plastic are thought to interfere with reproduction, stress responses, immune responses, and development. Microplastics in the ocean threaten marine life and birds, and although there are few studies on mammals, studies conducted on rats and mice point to serious harm.
However, the authors of the new study warn that the presence of microplastics in clouds could pose a whole new set of problems.
find plastic in the sky
Hiroshi Okochi, one of the study authors, said he was not surprised to find floating microplastics in the clouds above Mt.
“Early studies on atmospheric microplastics (AMP) found that they are present in atmospheric fallout, including rainwater,” Okochi said in an email. He and his colleagues hypothesized that if the tiny particles are in rainwater, they should also be in cloud water.
Studying this was not easy. The Mt. Fuji Research Station is located on the highest of Mt. Fuji’s eight peaks, next to an unobstructed cliff, allowing researchers to collect cloud water samples without interference from climbers or mountain huts. It’s done. They collected samples only during the summer at Mt. Fuji, which is about 3,800 meters or 12,400 feet above sea level. Researchers collect samples every few hours based on cloud density.
The research team analyzed whether cloud water contained plastic. Researchers discovered the material is used in many plastic products, including clear food wrap, shopping bags and detergent bottles. They then used a technique known as backward trajectory analysis to try to figure out where the plastic particles came from and how they became clouds in the first place.
“As a result of backward trajectory analysis, we found that the AMP in the cloud water collected at the summit of Mt. Fuji was mainly transported from Mt. Fuji.” [the] The sea,” Okochi wrote. Researchers believe that tiny marine microplastics are dispersed into the atmosphere by airborne waves.
The shape of plastic particles matters, and a new paper published this week in the journal Nature Geoscience says that shape plays a key role in how far they can travel through the atmosphere.
Scientists have long assumed, based on past models, that these particles are essentially spherical. Physicists even joke about how quickly they make such assumptions.
“We like to assume that everything is a sphere,” says Natalie Mahowald, a professor of atmospheric science at Cornell University and one of the study’s authors. However, this was inconsistent with the fact that spherical particles are known to fall to the ground faster.
A research group at Cornell University found that many of these particles may have a shape more like ribbons than balls. This flattened shape would explain why they are able to travel long distances and end up in all these remote locations.
Through modeling, the researchers confirmed that ribbon-shaped particles can stay in the atmosphere 450% longer, allowing them to travel much farther than spherical particles. The researchers also found that most of the microplastic particles they observed were flat.
“This paper uses some sophisticated theory to actually show why these microplastic fibers can be transported much further than you would think if you thought of them as spheres,” Mahowald said. said.
Microplastics and climate
Although the mechanism by which microplastics in clouds affect climate is still poorly understood, Okochi explained that when plastics break down, they can create surfaces for water to adhere to. This means clouds may form differently or disperse more quickly, which can affect temperatures and rainfall.
Another paper published last year in Nature Geoscience took a closer look at the potential impact of airborne microplastics on the climate.
“These particles are so small and light that they are carried to high altitudes. …Here, they may be involved in cloud formation,” said Zamin Kanji, one of the study authors. He teaches atmospheric experimental physics at the Institute of Atmospheric and Climate Sciences at the Swiss Federal Institute of Technology in Zurich.
Kanji said plastic particles in clouds can cause water to condense around them, forming water droplets and ice crystals in the atmosphere.
This could change the speed at which clouds turn into rain and the life cycle of clouds, which have an important role in reflecting sunlight from Earth.
Okochi also pointed out that strong ultraviolet light in the upper atmosphere could accelerate the deterioration of floating plastic particles, releasing greenhouse gases such as methane and carbon dioxide. “This has the effect of warming the planet,” he says.
Both Okochi and Kanji pointed out that the concentration of microplastics in clouds is currently too low to have a significant impact on temperature or rainfall.
“This may become an issue in a few decades,” Kanzi said. That means there’s still time to reduce the impact.
“We have a chance to stop this by taking action and not only cleaning up the existing environment, but also curbing continued pollution,” he said.