Date of Award

7-31-2018

Document Type

Thesis

Degree Name

Master of Science in Coastal Marine and Wetland Studies

Department

Coastal and Marine Systems Science

First Advisor

Till J.J. Hanebuth

Second Advisor

Shaowu Bao

Third Advisor

Stefanie Whitmire

Additional Advisors

Zhixiong Shen

Abstract

Although there is much concern globally regarding microplastic contamination in aquatic environments, there is little documentation on microplastic contamination concentrations within South Carolina inland waters and coastal areas. Specifically, Winyah Bay, SC should be of high priority for microplastic contamination evaluations as it is the third largest drainage basin (47,060 km2) and the second largest (157 km2) estuarine system on the east coast of the United States. Today, the general influencing physical factors on microplastic transport are mostly known by the scientific community, however, transport and deposition patterns of microplastics heavily vary by location depending on various physical, chemical, and ecological factors. We tested several different microplastic extraction techniques for Winyah Bay’s sample type and we advanced the methodology to be more efficient. Bottle and grab samples were taken from surface waters and surface sediment, respectively, within Winyah Bay and its associated rivers. Microplastics were extracted from water samples through plankton nets and sieves with hydrogen peroxide for organic matter digestion as needed. We found that filtering water samples through a sieve reduced processing contamination in comparison to filtering through a plankton net. Additionally, we found that extracting microplastics from muddy, thus strongly cohesive sediment samples, was more easily and efficiently accomplished using highly volatile kerosene instead of the commonly used canola oil of higher viscosity. The methodological development of extracting microplastics from these cohesive sediments was so time consuming, such that, no microplastic abundance data from sediments were produced from this study. The average (1.64 particles/L for 2016a, 6.24 particles/L for 2016b, and 0.31 particles/L for 2017; >63 µm, 28-50% particle recovery rate) is comparable to other microplastic abundances across the surface waters (~0.3 m) of the coastal eastern United States (i.e., Georgia: 2 particles/L and some Florida sites: 1-5 particles/L). Oppositely, the average is not as comparable to other sites of the coastal eastern United States (i.e., other Florida sites: 6-20 particles/L and Chesapeake Bay: 1-560 g/km2). Additionally, microplastic fibers made up 90% of the total microplastics collected from surface water samples in this study which is comparable to the domination of fibers also found in Georgia and Florida studies. This study adds to the demonstration that there is a consistent challenge in microplastic literature to compare between studies as each study uses different methods. Our data suggests that microplastic abundances in Winyah Bay, SC are influenced by precipitation (r = .411, p = .030) and tides (i.e., salinity (r = .402, p = .034), density (r = .422, p = .025), and tidal range (.400, p = .035)).

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