We know that microplastic pollution is a growing issue around the world, but how widespread is the problem? Janice Brahney, a researcher at the Department of Watershed Sciences, Utah State University in Logan, Utah, along with researchers at Salt Lake Community College, conducted a study of accumulate microplastic particles from remote areas of the western United States published in Science Magazine.
The study found significant rates of microplastic depositions from sources such as microbeads from paints and personal care products, and microfibers from clothing and industrial applications. These materials were found in both wet- and dry-deposited sample sources, concluding, “deposition rates averaged 132 plastics per square meter per day, which amounts to >1000 metric tons of plastic deposition to western U.S. protected lands annually.”
While certain microplastics in the study could be visually identified and counted by color, identifying many microplastics required the help of scientific instrumentation. Fourier-transform infrared (FTIR) spectroscopy is a fingerprinting analytical technique that compares collected samples with a database of known chemical compounds and is ideal for classifying polymeric materials.
The Utah research team turned to Suja Sukumaran, a spectroscopy scientist here at Thermo Fisher, to assist identifying polymer compositions of microplastics in dust particles collected on filters. They found that using an FTIR particle mapping technique, “2.5 to 5% (on average 4%) of the identifiable dust particles were synthetic polymers.”
An important part of the study was to determine the source, transport and distribution of these polymers. They found that microplastics deposited in wet conditions were larger in size, but less frequent, and were distributed from regional sources. “This observation reflects the role of regional storms in the entrainment and subsequent rainout of microplastics, as these storms often pass through urban centers or over erodible soils,” the authors noted.
In comparison, dry deposited plastics were smaller and accounted for over 75 percent of the accumulated plastic mass, representing distribution from broad-scale atmospheric patterns. “This suggests that dry deposited plastics are subject to large-scale, global dispersion,” the report states.
The report concludes that while urban centers are the initial source of microplastic pollution, they accumulate over time and transport over long distances, including remote areas of the western United States. “Identifying the key mechanisms underpinning plastic emissions to the atmosphere is the first step in developing scalable solutions.”
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