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There is no part of Western North Carolina untouched by microplastics. No river that flows without fibers. No rain that falls without microscopic debris.

Ģ������Ƶ researchers know this on principle. Studies published over the course of the last decade show that every corner of the earth, from the depths of the world’s oceans to the lakes on its tallest peaks, bears evidence of plastics contamination.

They’ve also performed the research to prove it here.

For the past few years, Jerry Miller, Whitmire Distinguished Professor of Environmental Sciences, has led a team of Ģ������Ƶstudents, local volunteers and professional researchers to study where particles of plastic less than five millimeters in size accumulate in the local watershed and, more recently, how they move about inside it.

The conditions created by Hurricane Helene offered Ģ������Ƶscientists the unique opportunity to study and compare the composition of these floodplain deposits in the wake of major flooding.

Their findings challenged their initial assumptions and begged new questions about the future of microplastics research.

In the Field

Miller first published a review on the subject of microplastics in rivers in 2019, highlighting them as a contaminant of emerging concern or CEC.

“These are essentially things you could be exposed to under chronic conditions, so at very low levels but almost constantly, and you don’t know how they affect either biota or individuals, and they usually occur in very low concentrations,” Miller said. “One of those was microplastics.”

Miller recognized the great disparity between the number of studies documenting microplastics in the world’s oceans versus the number of studies documenting microplastics in freshwater systems.

Given that lack, Miller was inspired to turn his lab’s attention to Western North Carolina’s waterways and was able to begin work with a grant from WCU’s provost's office in 2021.

Fortunately for Miller, another local academic, Jason Love, associate director of WCU’s Highlands Biological Station, was also studying microplastics in rainfall and local waterways with a small group of capstone students from the University of North Carolina, Chapel Hill.

After connecting, they were joined by volunteers from Tuscola High School and Haywood Waterways Association, who assisted with sample collection and, in time, received additional funding from the NC Sea Grant and the NC Water Resources Institute to continue their efforts.

Researchers and volunteers collected buckets of rainwater from Highlands and Waynesville, documented and removed 1,500 larger plastics at the banks of the Richland Creek watershed and gathered sediments at different sites along its course, from the 90% forested tributary Allen Creek through to several of the city’s public access points.

“One of the things we found was totally expected. As we go downstream through the town of Waynesville, concentrations of microplastics increase, suggesting that some of the plastics are coming in from runoff. So, as it rains, it comes off roads, comes through storm drains, those kinds of things are not too surprising,” Miller said.

“And one of the things that was surprising is that our control basin had relatively high concentrations, particularly given the fact that there was almost no development and no activities.

“If we compared it to global averages being reported in the literature today, we were in the upper 25%.”

They walked away from their findings with a new understanding of the correlation between human development, or anthropogenic activity, and microplastic pollution.

The concentration of microplastics and the overwhelming abundance of “fibers,” a particular shape of microplastics that abounds in the atmosphere, within that concentration, suggested to Miller and the researchers that atmospheric deposition was a significant factor.

Their rain bucket samples helped tell the story of how plastics ended up in these largely uninhabited areas.

“If you took a one square meter section, we get about 180 particles per square meter per day up at Highlands. We get about 100 particles down here in the Waynesville area, so it’s not trivial,” Miller said.

“Wet deposition during rainfall is significantly higher than dry, and we expect that, because you’re essentially washing those particles out of the atmosphere.”

Western North Carolina’s climate exacerbates the phenomenon, Miller explained. Small headwater streams also lack the ability to dilute themselves in the same manner as larger rivers with greater discharge.

Understanding this reality, Miller and his researchers began to ask new questions, namely focused on how those plastics moved through the water column and how they might impact the biota, the living organisms, within them.

These questions coincided with the arrival of Hurricane Helene.

In the Lab

Ģ������Ƶresearch assistant Nathaniel Barrett dons a neon green lab coat to enter Miller’s lab. The undergraduates he supervises there wear the same.

This fashion choice has nothing to do with style and everything to do with methods; it speaks to one of the technical difficulties of microplastic analysis.

Without a standard operating procedure defined by the global scientific community, WCU’s researchers have had to pioneer their own.

“Research can be very repetitive. We do the same thing over and over and over again, but it’s really exciting sometimes when we’re trying to develop new techniques,” Barrett said, 100 jars of dirt and whirring equipment behind him.

“We use density separation methods to pull plastics out of sediments … mixing them with some chemicals, pouring them through different glassware to separate the sediments from the microplastics.

“Once we’ve got the samples all filtered and processed, they’ll usually end up on a little microfiber filter paper that we will put in a petri dish and then examine under a dissection microscope.”

Barrett and the undergraduate scientists in the lab then document the number and variety of microplastics they see. Their green lab coats ensure their own contaminant sheddings are visible and distinct from their sample plastics.

A lack of global consensus and the ease of lab contamination are, unfortunately, just two of the many difficulties surrounding the study of microplastics.

Another has to do with the differences in their compositions.

Though researchers can categorize plastics with size and shape designations, their mobility in waterways is not uniform.

“We can construct hydrological models and do a pretty good job of looking at how that stuff moves through a river. What you run into with plastics is that polymers are quite different between one polymer and another,” Miller said.

“For example, some have a density less than water, and they float. Others have a density greater than water; they would typically sink. So, there’s no reason to believe that within the water column that they’d be evenly distributed,” Miller said.

“On top of it, the plastic particles have a little electric charge on it that does two things. You can attach other contaminants to it. And then, in addition, they will bind with sediments themselves, clay minerals, those kinds of things, and so they’ll form a little aggregate, and they’ll move as an aggregate through the system.

“So just understanding the movement and how it moves and being able to quantify that is difficult. And that’s going to be, from a physical perspective, a challenge in the future.”

After Helene

For Madeleine Smith, a student researcher hired on to the project, the challenge arrived in real time with the very first samples from Hurricane Helene.

“The deposits were pretty huge, and we were in a lucky position where we could sample them before the deposits were put back, because there were giant sandbars in parking lots,” Smith said.

She echoed Miller when offering her insight into microplastics' concerning behavior.

“When it comes to these size plastics, we’re not so much looking at the shape, because they’re so small,” she said. “We’re more concerned with their binding to sediments and their movement within small stream sediments… It’s complex, and that’s what we’re finding, really. There’s no clear, groundbreaking ‘oh, they do this, or they react with this,’ because they’ve been seen to be more mobile than sediment itself.”

Another impressive finding came when Smith and her fellow researchers compared the microplastic quantity in their pre-flood deposits with those they collected in the wake of Helene.

“There were actually fewer microplastics in the post-Helene samples that we gathered,” Smith said.

“In our study, we talked about how the erosive power of Hurricane Helene eroded away channel banks in the upstream areas that contained sediments from prior to 1950 - those are called pre-colonial.

“Prior to 1960, we didn’t have any plastics, so then that sediment that was plastic-free came rushing down the river and deposited on the floodplains, intermingling with more modern plastic, and then we came up with less plastics overall being found.”

Miller, Barrett and Smith, along with students Charlotte Banker, Avery Leeb and Parker MacDowell, presented their findings at the Southeastern Environmental Toxicology and Chemistry Conference in Charleston, South Carolina in April.

In the Future

The latest efforts by Ģ������Ƶresearchers examine the larvae of caddisflies, a type of microvertebrate that live in sediment casings constructed on the underside of rocks.

Scientists hope that with time and a greater understanding of the mobility of microplastics, they can work toward assessing their impact on living organisms and model what we might expect for the future.

For Smith, the harm is obvious. Though the literature is lacking in some areas, what we do now is alarming enough to cause concern.

“Plastics, in and of themselves, aren't always toxic, but the coating is often made with harmful chemicals. The coating, the surface area, binds to other harmful chemicals, and then they collect through tributaries and eventually deposit into the ocean. In the ocean, they can form these bio-aggregates with other chemicals and heavy metals and then those can be consumed by fish,” Smith said.

“Plastics, for all intents and purposes, will never leave our environment. They’re non-biodegradable. They bio-accumulate very easily, so they'll be in fish, they’ll then be in humans. They’ve found that once they enter the human body, they can enter every organ.

“From 1960 until now, about 70 years, they have already made their way into every single environmental compartment on Earth. We found them everywhere in the Arctic or in the deep coral reefs, so it's just a question of ‘What are we going to do?’ There's not much we can do to tackle something so small and so big at the same time.”

Whether or not there is an issue to be tackled remains largely uncertain. Some researchers, like Barrett, are optimistic about their omniscience.

“We don’t know the impacts of plastics just yet. That’s something we are just trying to study. There’s a chance that they could have a strong negative impact on our ecosystem, but we don’t know that for sure,” Barrett said.

“The world’s forever evolving. I think there’s a chance that ecosystems could evolve to just put up with plastics. We don’t know that for sure, but also plastics are not all bad. We would not have the society that we have without plastics.”

While the full scope of microplastics’ impact may be past our current understanding, what is certain is that Ģ������Ƶresearchers will continue to contribute valuable insight from the front lines of the field.