(CN) — Scientists measured microplastics — tiny particles and fibers of plastic that can float in the air like dust — and found that over 1,000 tons a year are falling into wilderness areas and national parks in the western U.S.
Janice Brahney of Utah State University and her team identified samples of microplastics and other particulates collected over 14 months in 11 national parks and wilderness areas to create the study published Thursday in the journal Science.
Pieces of plastic less than 5 mm in length, or microplastics, occur in the environment as a consequence of plastic pollution. Microplastics are present in a variety of products, from cosmetics to synthetic clothing to plastic bags and bottles. Many of these products readily enter the environment in wastes.
Microplastics are divided into two types: primary and secondary. Primary microplastics are those manufactured to be tiny, such as microbeads found in personal care products, plastic pellets (or nurdles) used in industrial manufacturing, and plastic fibres used in synthetic textiles.
Secondary microplastics form from the breakdown of larger plastics; this typically happens when larger plastics undergo weathering, through exposure to wave action, wind abrasion, and ultraviolet radiation from sunlight.
The presence of microplastics in oceans and water supplies has been a matter of concern for some time, but the impact of airborne microplastics is a relatively new area of study. Though microplastics are found nearly everywhere on Earth, the sources and processes behind their ubiquitous distribution, or the “global plastic cycle,” remain vaguely understood.
Initially overlooked, recent studies have suggested that long-range atmospheric transport plays an important role in carrying microplastic pollution vast distances and to remote locations.
Using filters placed at field sites, researchers conducted visual counts of tiny microplastic beads, fibers and fragments deposited by wind and rain in the protected land areas.
What they found surprised even the research team.
“We were shocked at the estimated deposition rates and kept trying to figure out where our calculations went wrong," Brahney said. "We then confirmed through 32 different particle scans that roughly 4% of the atmospheric particles analyzed from these remote locations were synthetic polymers."
Examination of weekly wet and monthly dry samples from 11 sites allowed the authors to estimate that more than 1,000 tons of microplastics are deposited onto protected lands in the western U.S. each year, equivalent to more than 123 million plastic water bottles.
The ubiquity of microplastics in the atmosphere has unknown consequences for humans and animals, but the research team observed sizes of particles that were within the ranges that accumulate in lung tissue. Moreover, the accumulation of plastic in the wilderness areas and national parks could well influence the ecosystems in complicated ways.
“This ubiquity of microplastics in the atmosphere and the subsequent deposition to remote terrestrial and aquatic environments raise widespread ecological and societal concerns," Brahney said. "Identifying the key mechanisms of plastic emission to the atmosphere is a first step in developing global-scale solutions.”
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