Date of Award

Spring 2026

Document Type

Open Access Thesis

Department

Marine Science

First Advisor

Tammi L. Richardson

Abstract

Microplastics (1 μm to 5 mm) accumulate in the bodies of marine organisms and negatively impact their health. Microplastics have also been linked to birth defects, endocrine disruption, and cancer in humans. This study quantified, characterized, and compared microplastics in a protected estuary (North Inlet Estuary, South Carolina) and an estuary impacted by anthropogenic activities (Winyah Bay, South Carolina). Water samples were taken from three sites in each estuary from February 2025 to December 2025. The samples were digested, filtered, then examined visually for microplastics. Plastic particles were extracted and analyzed by Raman microscopy to obtain polymer content. Results indicate a significant difference in plastic abundance between North Inlet and Winyah Bay (p=0.03) and in composition (p = 0.006). Fibers were the most abundant plastic type in both estuaries (p< 0.001). There was a significant interaction found between sampling month and site for microplastic type. A significant interaction was also found when analyzing polymer and season, with polyethylene, polyester, and polypropylene showing distinct seasonality (p< 0.05). My results show that microplastic types depends on seasonal use patterns of specific sites, and that overall polymer abundances shift seasonally. It is essential to investigate the presence of microplastics in estuaries to understand their impacts on both environmental and human health. This research will advance our understanding of microplastic contamination in South Carolina estuaries, characterizing how concentrations vary across temporal and spatial scales.

Rights

©2026, Emily Grace Contract

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