Microplastics increasingly found in Colorado’s snowpack
As the focus on the electron microscope resolved, Richard Reynolds found himself feeling more resigned than surprised.
The slide before him was a snowpack sample collected from pristine Colorado high country. The sample revealed, at intense magnification, the snowpack’s expected sprinkling of rock fragments and spikey grains of sand.
It also revealed what shouldn’t have been there at all: long, straight, human-made fibers of plastic.
The sight confirmed what Reynolds, a retired U.S. Geological Survey researcher, and his colleagues had suspected after seeing snowpack studies from far away places: An invisible layer of microplastic blankets the Rocky Mountains, polluting our snowpack and our water in yet undefined ways.
“It seems to be everywhere,” said Reynolds, coauthor of a new study of the microplastics detected throughout the Upper Colorado River Basin.
“And there’s a lot of it.”
Fragments of shredded truck tires blown in from nearby highways. Pieces of plastic bottles lifted from a Utah landfill by siroccos and dropped onto Loveland Pass. Detritus from the Pacific garbage patch catapulted by El Nino into the San Juan mountains. The microplastics on the slides are too tiny to offer identities like brand names or shapes. But those distant sources are the initial suspicions of the research team as they plan followup studies on more samples.
A host of wildlife and water quality researchers are likely to descend on the study results to gauge impacts of invisible plastic fibers riding snowmelt into every crevice of the high country. They’ll also be looking for any dangers for the cities downhill that rely on that water.
“Microplastics are very persistent. So where are they going to end up?” said Steven Fassnacht, professor of snow hydrology and a senior research scientist at Colorado State University. Fassnacht was not involved in the USGS microplastics study, but is familiar with the team’s work.
“I think we’re going to start seeing more and more microplastics in fish, and in our drinking water,” he said.
For now, the immediate news is bad enough: Much like the dark red dust that blows onto the snowpack from Colorado Plateau and Great Basin storms and creates rust-colored layer cakes above treeline, the microplastics may absorb sunshine and speed up snowmelt.
The previously known impurities in Colorado snow had already piled on the current 22-year drought and long-term climate change to threaten state water resources and outdoor recreation that rely on deep winters. Darker dust layers are an “accelerant” to early snow loss, researchers say. Drought in turn worsens the dust storms by stripping the moisture that binds soil together across the West.
“Climate change is showing its ugly head now,” said Jeff Derry, a coauthor of the microplastics study and executive director for the Center for Snow and Avalanche Studies which has sensors across the San Juan Mountains. “This year in southern Colorado we saw the snow melt essentially a month early.”
— New study adds layer of bad news
Reynolds and USGS researchers Harland Goldstein and Raymond Kokaly had been working with Derry’s center for years to investigate the samples he brought back from high country sites.
Until recently, they focused on identifying where the dust in the snow layers blew in from, and analyzed mineral content and the physical properties that speed up snowmelt by absorbing more solar energy than pure white snow. This is the “albedo,” with a scale that starts at 0 for so dark it absorbs everything, up to 1, a perfect reflection of the energy.
But the whole crew was also seeing more and more disturbing journal articles about human-made impurities showing up in samples around the world. So much plastic is produced each year, for everything from water bottles to clothing to industrial goods to packaging, and so little is recycled, that it bumps and shreds and chips and blows and drifts everywhere.
Plastics are fragmented, but never degraded, at least not in a timespan relevant to life on this planet.
“The world produced 348 million metric tons of plastic in 2017, and this number grows every year by about 5%,” begins a study by Utah researchers published in the journal Science in 2020. “A large proportion of this production accumulates as waste in the environment, and progressive fragmentation” sends the microplastics abroad on the wind, the study said.
The abstract title of their report is “Here, there, and everywhere.”
“Eleven billion metric tons of plastic are projected to accumulate in the environment by 2025,” they add.
The Colorado report’s authors point out that before they retrained more powerful microscopes on their past samples, researchers had found airborne microplastics elsewhere in the western United States, on Arctic ice floes, and high in the Pyrenees and Alps.
“Recently, microplastics have been identified in human blood and lung tissue,” the Colorado study adds, in scientific deadpan.
Standing atop Loveland Pass in mid-July, Reynolds said he had noticed straight lines and unnatural filament shapes on some slides in his first pass through some of Derry’s dust samples, but had dismissed them as microbes that can assume similar shapes. After reading enough microplastics studies from other continents, he realized he and others had missed something.
Derry at first wondered if they had accidentally contaminated the samples. Maybe the straight lines were stray, infinitesimal threads from one of his countless shell jackets or skiing gaiters.
But as the Colorado researchers went back through with more powerful tools, the plastics were unmistakable. And yet still shocking, at least to Derry, who lives for work-related backcountry ski runs around Silverton.
“There’s no place that’s safe from our influence and contamination of the Earth,” Derry said.
Possible contributors to the microplastics seem endless once you start thinking about how they got to 11,000 feet, Derry said. The snow and avalanche center has a Colorado Dust-on-Snow Program with sampling sites that sit on passes like Berthoud, Rabbit Ears, Hoosier, McClure and Wolf Creek.
He suspects tires wearing away constantly on mountain highways, and even drifting clouds of industrial and consumer microplastics swept into the atmosphere from municipal wastewater biosolids spread on Eastern Plains farms.
The samples in the new Colorado study went through 2016, and the researchers are now seeking samples from more recent snow surveys and new regions. Perhaps the only really useful function of work conferences, Reynolds said, is that after presenting a new paper, everybody in the audience sends you samples.
The Colorado researchers said they saw samples over enough years to make them suspect the microplastics problem is getting worse, though they can’t be conclusive yet on this point.
Dozens of samples from water years 2015 and 2016 — water years begin in October to better track one winter’s snowpack and melt — found the frequency of microplastics at the 11 Upper Colorado River Basin sites were greater than in 2013 and 2014.
That doesn’t mean the researchers are ready to conclude the tiny plastic fragments are torching snow banks like a hot black battery pack. They know impurities are bad, but they need to study more about plastics’ absorption or reflection of light, they said.
“Whether or not our observations indicate an increasing influence of microplastics on snow-surface albedo remains an open question,” they conclude.
— After the deluge
But it all has to go somewhere, right? The snow melts. Faster than ever, according to the original research that led to the microplastics discoveries. So what happens to all those microscopic shreds of petroleum-based fibers?
And of course they’re not just getting deposited up high during winter snow and wind storms. Any spring or summer storm is dropping more microplastic straight onto the plants and dirt.
Scientists from any number of fields are now sorting through microplastics studies from the high country and plotting followup research, CSU’s Fassnacht said.
The microplastics wash downhill and end up in mountain streams for wildlife to drink, or swim and breed in. What happens inside animal bodies, if anything? Is more microplastic worse?
Upstream in the food chain, do tundra plants and streamside plants take up the microplastics through their roots? How does it impact their growth? What happens when animals eat them?
And then, of course, there’s the downstream questions. Front Range cities pride themselves on basing their drinking water supplies on snowmelt from the Colorado, Arkansas and South Platte river basins. How much of the microplastic ends up at the intake valves for a city water supply? And does water treatment take it all out?
“We rely on that water, and these are impurities that we don’t really know much about,” Fassnacht said. “We are just starting to evaluate and measure how much is there.”
There are likely to be a series of long-term studies coming out of the microplastics revelations, he said. A model could be the decadeslong measuring of atmospheric pollution at Loch Vale, in the heart of Rocky Mountain National Park, where researchers have measured excess nitrogen deposited from industrial, automobile and agricultural pollution on the Front Range.
“We need to look at this as a system, and how does it move through the system,” Fassnacht said. “Because we may be taking most of it out of the drinking water. But if we’re eating the fish in the rivers …”
Research on the potential toxicity of microplastics in water appears to be in its infancy. A 2019 World Health Organization metastudy found the tiny shards and fibers everywhere in water supplies and wastewater effluent. But the report also said “routine monitoring of microplastics in drinking-water is not recommended at this time, as there is no evidence to indicate a human health concern.” Water treatment agencies should never take their eye off the ball of the constant and quantifiable dangers of dangerous microbes, the WHO said.
Besides, the WHO concluded, “it is likely humans have ingested plastic particles for decades as a result of widespread contact with plastics in household objects including cutting boards, food packaging and direct contamination in air and food.” The WHO recommended far more research into both the quantity and the potential impacts of microplastics in the water supply.
“Even if you aren’t surprised to hear it, it’s still depressing,” Derry said, of reading through international reports.
California, as it is wont to do, is regulating first, and asking questions later.
High Country News detailed California’s 2021 moves to require drinking water measurements, but noted the microplastics field “is still in its infancy. No one knows how widespread microplastics in California’s drinking water really are. There isn’t even a standardized method to test for them. And no one knows what dose may be ‘safe’ to consume, since the human health effects are largely unknown.”
Count Aurora Water in the too-early-to-say category. Spokesman Greg Baker said Aurora is not testing for microplastics in its high country water sources around Leadville and in the Arkansas River basin.
Denver Water said it is closely following what it calls an “emerging issue” with microplastics in runoff. Agency officials said they would add monitoring, watershed management and treatment if needed to ensure “Denver’s tap water always meets or goes above and beyond” strict federal water quality standards.
— Try not to think about what’s underfoot
Geologists live to learn what they are stepping on.
On hikes and other outings, Reynolds brings a magnetic susceptibility meter the size of a wallet, to hover over snow dust layers or trailside rocks. With a click, Reynolds sees the level of iron oxide arrayed before him, and can make an educated guess on how deep into Utah a given dusty layer came from.
After Reynolds and Derry met on Loveland Pass in mid-July to talk microplastics, Reynolds put the meter in his pocket, slung on a backpack, and hiked straight up the ridge toward Mount Sniktau. He spent most of the hike thinking about oxygen, or lack thereof, at 11,990 feet. But the persistent microplastics questions returned when he was back in his car.
How much of the potentially toxic shred is out there? Will Derry find much more in the samples he’s taken since 2017?
Will scientists zero in on where all the plastic is coming from, and will that lead to ways to stop it?
How toxic might the fibers and shards prove to plants, to wildlife, to humans?
In microplastics, as in all of science, Reynolds said, “I am continuously humbled by what I don’t know.”
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