The incredible amount of plastic that humanity produces and throws away is now moving through Earth’s oceans and atmosphere in a complex, eternal cycle. New research published in Proceedings of the National Academy of Sciences analyzed the abundance of microplastics in the atmosphere and their origins, showcasing the broad geographic reach of microplastics around the globe.
The study found that microplastics are not only found in the ocean and the soil, but in the air as well. Microplastics, which are pieces of plastic measuring five millimeters or smaller, are broken down through processes like wave action in the ocean or the movement of tires on roads. These microplastics can be eaten by fish and other animals, flow into bodies of water, and lifted up into the air by atmospheric winds.
The Origin of Legacy Plastics
Recent studies show that these bits of plastic are more prevalent than we realized. Those involved in this research found it to be next to impossible to determine the origin of much of the microplastics as they have become so homogenized in the environment. Atmospheric models were utilized in order to show the physical location of where the microplastics blew in from based on air circulation patterns and climate data.
Microplastics can become aerosols through a variety of processes, including wave action, the movement of tires across road surfaces, and via agriculture. These microplastic aerosols can travel for an hour or up to a week, carried by air currents like the jet stream.
Researchers found that these plastics were not new, but were ‘legacy’ plastic- that is, plastic that has been dumped into the environment over the course of decades. These microplastics were concentrated not in urban areas as assumed, but were found in areas like the rural American West, national parks, and other remote locations.
In the Western United States where the study was focused, the researchers found that 84% of microplastics taken from air samples came from road dust, 11% came from sea spray, and 5% were a result of agricultural soil dust. The microplastics that came from sea spray far exceeded researchers’ estimates; the study concludes that the ocean may be producing more microplastics as a result of decades of dumping than new plastic is being put into the marine environment.
Plastic in the Breeze
Approximately 1,100 tons of microplastics are thought to be floating in the air above the Western United States. Additional research is needed on other locations around the world to see if changes in climate, such as wetter environments, may reduce the amount of microplastic aerosols.
The presence of microplastics on the land, in the water, and in the air paints a dim picture of humanity’s impact on the Earth. This material is not easily broken down, and microplastics will continue to cycle through and impact our environment long after we are gone.
Brahney, J., Mahowald, N., Prank, M., Cornwell, G., Klimont, Z., Matsui, H., & Prather, K. A. (2021). Constraining the atmospheric limb of the plastic cycle. Proceedings of the National Academy of Sciences, 118(16). https://doi.org/10.1073/pnas.2020719118
Simon, Matt. Plastic is Falling From the Sky. But Where’s it Coming From? 13 April 2021. Retrieved from https://www.wired.com/story/plastic-is-falling-from-the-sky/
Neill, Pippa. Microplastics are contaminating our air, new research suggests. 13 April 2021. Retrieved from https://airqualitynews.com/2021/04/13/microplastics-are-contaminating-our-air-new-research-suggests/
Friedlander, Blaine. Atmospheric travel: Scientists find microplastics everywhere. Cornell Chronicle. 12 April 2021. Retrieved from https://news.cornell.edu/stories/2021/04/atmospheric-travel-scientists-find-microplastic-everywhere