From Highlands to Tsukuba

Charles Bowers, Jordan Britt, Savannah Carter, Olivia Dail, Parker Edwards, Jonah Ettore, Odell Escorcia-Puente, Gray Hamby, Adriana Kirk, Stuart MacMillan, Laura Melton, Rachel Price, Yanira Rodríguez Mendez, Hannah Shepard, Yuguo Tan, David Utz, Lawrence Weindorf, Radmila Petric, Austin Gray, Olivia Swift, Katie Bower and Jason Love

Institute for the Environment, University of North Carolina at Chapel Hill; Highlands Biological Station, Western Carolina University; Department of Biological Sciences, Virginia Tech; Warnell School of Forestry and Natural Resources, University of Georgia; USDA Coweeta Hydrologic Laboratory

Global plastic production continues to increase by ~8% annually despite growing concerns about its environmental and human health impacts. Recent studies have demonstrated that forested headwater streams in the Southern Appalachian Mountains of western North Carolina contain some of the highest concentrations of microplastics (MPs) ever recorded in freshwater systems; however, concentrations of MPs in rivers within this region and across different years have not been examined. We used Golden Clams (Corbicula fluminea) as biological indicators to assess changes in MP concentrations from 2018 to 2025 at six sites in the Little Tennessee River basin in western North Carolina, USA. For a more complete understanding of MPs in the whole freshwater system, atmospheric deposition and stream water samples were also collected and analyzed. Overall, from 2018 to 2025, we found a 54.5% increase in the mean number of MPs in our clam samples and a 73.9% increase in the mean MPs per gram of clam tissue, although those results varied among the six sites. Consistent with 2018 observations, fibers were the most prevalent type of MP, accounting for >90% of particles found in atmospheric samples, stream water samples, and clams. Our findings on counts and concentrations of MPs in Golden Clams are among the highest ever recorded from bivalves. We also found that MP counts and concentrations were high even in remote sections of the Little Tennessee River, which is considered a biodiversity hotspot for rare fish and freshwater mussels. Our findings support the need for further research into the pervasive nature and effects of MPs on freshwater systems and their influence on biodiversity, as native bivalve populations have experienced enigmatic declines in recent decades.

DisclosureFunding sources: National Science Foundation award DEB-1637522 from the Long Term Ecological Research Program to the Coweeta LTER Program at the University of Georgia, Tennessee Valley Authority, Highlands Biological Foundation, North Carolina Sea Grant & Water Resources Research Institute, Collaborative Community Research Grant (grant number 22-CCRG04). Clams were collected under North Carolina Wildlife Resources Commission Scientific Fish Collecting Permit #SFC25000053.

Session1.07.P · Impact of Microplastics on Aquatic Organisms

Erin Flanagan, Annika Willis, Radmila Petric, Bruce Snyder, Austin Gray and Jason Love

Institute for the Environment, University of North Carolina at Chapel Hill; Department of Biological and Environmental Sciences, Georgia College and State University; Department of Biological Sciences, Virginia Tech; Highlands Biological Station, Western Carolina University

Microplastics (MPs, <5mm) are ubiquitous global contaminants, yet there is little information about their fate through terrestrial food webs. In the Southern Appalachian Forest of the United States of America, the atmosphere is a major source of MP pollution for the area. We provide the first assessment of MPs in wild shrews (Sorex cinereus, Sorex fumeus, Blarina brevicauda) and earthworms (a common shrew food source) collected. Following dissection, we harvested shrews heart, lungs, liver, kidneys, gut, and brain to examine MP presence and composition among organs, while earthworms were sampled as a whole organism. Thirty earthworm and organs of 19 shrews were digested with hydrogen peroxide, filtered, and examined microscopically to assess MP count, type, and color. A subset of samples was analyzed via Raman Spectroscopy to identify the type of plastic. We found that shrews had 55% higher MP concentrations per gram of tissue than earthworms. We also found differences in MP concentration across shrew organs, with the highest mean concentration in the lungs (48.8 MP/g) and heart (20.4 MP/g) and the lowest in the gut (4.1 MP/g). Fibers were the most common plastic morphology found in the samples. Our results suggest possible biomagnification or trophic transfer of MPs in this terrestrial food chain. Furthermore, differences in MP concentrations among tissues could be attributed to differences in cellular turnover rates. Our results demonstrate the ability for MPs to be accumulated and transferred up trophic levels in terrestrial ecosystems.

DisclosureFunding for this research was provided by the Institute for the Environment at the University of North Carolina at Chapel Hill, Highlands Biological Station and Western Carolina University.

Session1.06.P · Exposure and Effects of Micro- and Nanoplastics in the Environment and Implications for Ecological Risk Assessment

Rachel Price, Yuguo Tan, Lisa Gatens, Jason Love, Radmila Petric and Austin Gray

Institute for the Environment, University of North Carolina at Chapel Hill; North Carolina Museum of Natural Sciences; Highlands Biological Station, Western Carolina University; Department of Biological Sciences, Virginia Tech

Plastic production has increased since the 1950s due to its low cost and versatility, raising concerns about environmental and health impacts. As plastics degrade, they form microplastics (MPs) that can be ingested or inhaled and subsequently accumulate in animal tissues. While the effects of MPs on marine organisms are relatively well studied, exposure pathways and impacts in terrestrial systems remain poorly understood.

Eptesicus fuscus (big brown bats) are widespread North American insectivores that can serve as bioindicators of MP exposure through airborne, aquatic, and insect-mediated pathways. In this study, we evaluated 18 bats across six counties in North Carolina, USA. We assessed MP presence in the heart, lungs, liver, kidneys, and gastrointestinal tract and tested whether urbanization predicts MP burden. An urbanization index was developed using population density, impervious surface cover, and tree canopy metrics. Specimens were obtained opportunistically as a byproduct of the rabies testing.

We found MPs in every bat organ tested with the highest concentration of MPs in the gastrointestinal tract and lowest in the lungs. Total MP burden per individual bat was not correlated with urbanization levels; however, urbanization levels were positively correlated with MP counts within the gastrointestinal tract. These findings suggest that the primary mechanism of MP exposure in big brown bats is via ingestion. This study highlights the potential for widespread terrestrial exposure and underscores the need to better understand alternative pathways of microplastic uptake in insectivorous wildlife.

DisclosureUNC Institute for the Environment

Session1.06.A.T · Exposure and Effects of Micro- and Nanoplastics in the Environment and Implications for Ecological Risk Assessment

Nathaniel Barrett, Jason Love, Jerry Miller, Rada Petric, Robert Youker, Xinyue Huang, Hosein Foroutan and Austin Gray

Virginia Tech; Highlands Biological Station; Western Carolina University; University of North Carolina

Due to global warming, we can expect more intense hurricanes, leading to higher precipitation than previously observed. Historic storms, such as Hurricane Helene, that hit the southeastern United States in September 2024, deposited between 508 to 762 mm (20-30 in) of rainfall in rural, mountainous parts of Western North Carolina, causing catastrophic damage from flooding. Less known is the extent of microplastic (MP) deposition in these less-developed areas, as MP levels are largely influenced by development, population, and traffic. While there is insight into MP deposition due to typhoon events in the eastern parts of the world, in our assessment, we conducted the first-ever study assessing MP deposition in a severely affected region at multiple locations (Iron Duff, Coweeta Hydrologic Laboratory, and Highlands Biological Station (HBS) in the southeastern US, months before (January to September), during (September), and weeks post-storm (October to November). Our findings show that Hurricane Helene contributed to elevated MP deposition at all sites, where total storm MP deposition was 1,280, 2,179, and 10,243 MP/m² at Iron Duff, Coweeta, and HBS, respectively. This historic storm accounted for 4.2%, 4.6%, and 18.8% of the annual MP deposition at Iron Duff, Coweeta, and HBS, respectively. Using backward trajectory analysis, we found that air masses reaching our sampling locations differed between the Helene and pre- and post-Helene periods. Our regression model estimated that the total anomalous deposition over the area affected by Hurricane Helene (3,798,756.55 km²) was 3.85 × 10¹⁵ MPs (385 quadrillion MPs). Polyamide, polystyrene, polyethylene terephthalate, polypropylene, and polyethylene were the main polymers detected before and during Helene. Our findings underscore how extreme storms can produce short-term spikes in MP deposition above ambient levels in a region and highlight how abundant MPs are in the atmosphere.

Session2.08.B.T · Innovations in Understanding the Chemical Fate and Exposure of Plastics in the Environment