This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: Loose fibers from functional clothing, discarded PET bottles or abandoned packaging: When such plastic materials enter the environment, they often persist there for a long time. UV radiation, precipitation and ozone cause them to become brittle—and over time, mechanical forces break them down into increasingly smaller particles.
Swirled up by the wind, they are carried farther through the atmosphere. Until now, it was unclear how much microplastic ends up back in Swiss soil and water bodies through this process. Researchers at Empa, together with colleagues from Eawag and Agroscope, have now systematically documented this for the first time.
According to the study, which was supported by the Federal Office for the Environment (FOEN), approximately 219 metric tons of microplastics settle in Switzerland each year in areas below 2,000 meters (6,560 feet) in elevation. The research is published in the journal Atmospheric Chemistry and Physics. "Sensitive" areas are particularly relevant here: The researchers estimate that about 78 metric tons settle on agricultural land and about 10 metric tons settle directly into water bodies each year.
Measurements were taken over an entire year at five locations: Zurich, Dübendorf, Magadino, Payerne and Mount Chaumont in the Jura Mountains. Each month, the researchers collected samples of wet and dry deposition—that is, particles captured and washed out of the air by rain and snow, and those that settle due to gravity. The researchers analyzed microplastic particles with diameters ranging from 20 to 215 micrometers.
At the urban site in Zurich, they found an average deposition of 881 particles per square meter per day. At the other sites, the values—ranging from 249 to 331 particles per square meter per day—were significantly lower and relatively similar. It comes as little surprise that Zurich has more than twice the level of contamination.
Dense population, traffic and plastic products in outdoor spaces all contribute to this. What was more unexpected for the team led by Empa researcher Christoph Hüglin, however, was how similar the values were outside big cities. "The closer the location is to densely populated areas, the higher the levels we would have expected.
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