Microplastics contaminate Montana snow, rain, researcher finds

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BOZEMAN — Fibers of polyester and other pieces of microplastic have been found in dozens of snow samples taken over the past year from Big Sky Resort, Teton Pass and other Rocky Mountain sites.

Bekah Anderson, a Montana State University senior majoring in chemical engineering, used microscopes and other specialized laboratory tools in MSU’s Center for Biofilm Engineering to analyze the samples, which also reveal plant pollen and dust.

“All the pieces I’ve found so far have been small fibers that seem to be from fabrics like fleece,” Anderson said, noting that many kinds of outdoor clothing are made of finely spun plastic fibers. “We think that’s because they’re fine enough to get whisked up into the atmosphere.”

Previously, scientists have documented the presence of microplastic in streams and other water bodies, but the MSU study is among the first to examine the man-made particles directly in precipitation, according to the project’s leader, Christine Foreman, associate professor in the Department of Chemical and Biological Engineering in MSU’s Norm Asbjornson College of Engineering.

“It’s been exciting, but also saddening, to find so much microplastic in snow,” Foreman said. The team’s preliminary results are significant because they suggest the synthetic fibers are prevalent throughout the water cycle and not just in certain waterways.

Other studies have found microplastics in snow samples from the Arctic to the Alps. A June study estimated that Americans eat an estimated 39,000 to 52,000 microplastic particles, a number that climbs to 74,000 and 121,000 when inhalation is considered. 

Microplastics are “an emerging concern,” Foreman said. Not much is known about how they affect ecosystems, but it’s reasonable to suspect the petrochemical particles are being consumed by some aquatic organisms, she said. Scientists have warned that microplastics have a number of impacts on insects and fish, including clogging up digestion and disrupting hormones that regulate bodily functions.

Research into the effects of airborne microplastics on humans is still relatively new, but scientists are concerned that the fibers can also contain pollutants, dyes, additives and pigments that can harm human health when inhaled.  

In the lab, Anderson passed each sample of melted snow, as well as rain, through a fine filter that collects any particles. Then she applied a dye that binds to plastic. A certain kind of light applied under the microscope causes the dye to fluoresce, making any microplastic stand out. Using another technique called Raman spectroscopy, which measures how light interacts with a material’s molecular composition, Anderson can determine what kind of plastic each particle is made of.

“It’s important for us to understand the consequences of our plastic use,” said Anderson, who is from Golden, Colorado.

When she presented early results from the project last March at the Western Regional Honors Conference, which brought top students from across the western U.S. to MSU to present their research, Anderson won the award for the best poster presentation.

Anderson, whose work in Foreman’s lab is funded by MSU’s Undergraduate Scholars Program, also presented at the 2019 National Conference on Undergraduate Research in Kennesaw, Georgia. When MSU hosts the event on March 26-28, 2020, more than 4,000 students from around the world are expected to convene on the Bozeman campus to share their research.


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