Date of Award
8-2026
Document Type
Thesis
Degree Name
Master of Science (MS)
Department
Environmental Engineering and Earth Science
Committee Chair/Advisor
Dr. Kelly Best Lazar
Committee Member
Dr. Elizabeth Carraway
Committee Member
Dr. Alexander Pullen
Committee Member
Dr. Jeffrey Wilcox
Abstract
Microplastics are contaminants of emerging concern whose ubiquity across natural environments results in their involvement in many kinds of natural processes, including transportation and deposition in natural systems. The purpose of this thesis is to characterize microplastics and determine the mechanisms that affect their distribution, transport, and sequestration within known Hurricane Helene flood deposits in fluvial and Southern Appalachian wetland environments after Hurricane Helene in Asheville, North Carolina. Four fluvial and four Southern Appalachian wetland environments were sampled after Hurricane Helene. Samples collected in fluvial environments were taken as grab samples from surficial sandy flood deposits left behind by flooding during Hurricane Helene, and samples collected in Southern Appalachian wetlands were taken in the form of sediment cores. Both fluvial surficial and wetland core samples were digested in hydrogen peroxide to decrease organic material, density separated in a sodium chloride solution to isolate microplastics, sieved to isolate particles by size, and examined for microplastics using laser direct infrared spectroscopy (LDIR). Surficial samples were also examined using light microscopy, and core samples were further examined for microplastics using flow imaging microscopy (FIM). LDIR analysis revealed that microplastics were present in all samples, both surficial and core. Microplastics found were composed of acrylonitrile butadiene styrene, synthetic polyamides, polyethylene, polyethylene terephthalate, polylactic acid, polyoxymethylene, polytetrafluoroethylene, polyurethane, polyvinyl chloride, polymethyl methacrylate, polypropylene, and rubber, while natural particles were composed of cellulosic materials, chitin, naturally occurring polyamides, and sand. Wetland core samples generally contained more particles, both microplastic and natural, than surficial samples. Microplastic morphologies also differed between sites, with surficial samples dominated by fibers while core samples were dominated by fragments and beads. Results demonstrate that fluvial and wetland environments in Western North Carolina are experiencing microplastic contamination after flooding caused by Hurricane Helene, and that differences in hydrodynamic mechanisms, depositional processes, and microplastic properties determine the distribution, transport, and sequestration of microplastics in these two types of depositional environments during and after extreme flooding. Flooding mechanisms, sediment grain size, and microplastic properties affect microplastic distribution, transport, and sequestration in fluvial environments, and flooding mechanisms, soil characteristics, hydrogeologic processes, sediment deposition patterns, and microplastic properties determine microplastic distribution, transport, and sequestration in Southern Appalachian wetlands. Ultimately, this thesis adds to the body of existing microplastics research and contributes to investigation into the lasting impacts of Hurricane Helene.
Recommended Citation
Sgan, Abigail, "Characterizing Microplastics in Flood Sediments After Hurricane Helene in Asheville, North Carolina" (2026). All Theses. 4817.
https://open.clemson.edu/all_theses/4817