SOURCE: The Guardian

DATE: June 11, 2020

SNIP: Microplastic particles equivalent to as many as 300m plastic water bottles are raining down on the Grand Canyon, Joshua Tree and other US national parks, researchers have found.

In a survey of 11 remote western locations, also including the Great Basin and Craters of the Moon national parks, researchers discovered more than 1,000 metric tons of microplastic particles that had traveled through the atmosphere like rain or water particles.

Most microplastics are fragments from larger pieces of plastic. Since plastics aren’t biodegradable, plastics that end up in waste piles or landfills break down into microparticles and make their way through the Earth’s atmosphere, soil and water systems.

Janice Brahney, lead researcher and professor of watershed sciences at Utah State University, calls this process “plastic spiraling” – and some microplastics have been traveling through natural systems for a long periods.

“Plastics could be deposited, readmitted to the atmosphere, transported for some time, deposited and maybe picked up again,” Brahney said. “And who knows how many times and who knows how far they’ve travelled?”

Brahney’s team found that so-called wet microplastics, named for the way they are transported via wet atmospheric conditions, had most likely been disturbed by a storm and swept up into the atmosphere, and originated in larger urban areas. Dry microplastics, by contrast, mimicked the dispersal patterns of dust patterns and traveled long distances, often across continents.

Brahney warned that new findings show an urgent need to reduce plastic pollution. Although their full effects on the human body are still unknown, scientists are starting to raise public health concerns over microplastic particles: they’re small enough to lodge into lung tissue, which causes lesions and, in some cases of routine exposure, asthma and cancer. A 2019 study found that in an urban Danish apartment, the average person inhaled about 11 microplastic particles per hour.

Scientists have also linked microplastic particles to fluctuations in soil thermal properties, leading to losses in plant life.