Degree
Doctor of Philosophy (PhD)
Department
Oceanography and Coastal Sciences
Document Type
Dissertation
Abstract
Coastal regions are uniquely vulnerable to a myriad of natural and anthropogenically caused stresses such as hurricane strikes and chronic microplastic pollution. Both hurricanes and microplastics have major negative effects on global coastlines and are forecast to become more damaging in the future. However, current model trends are based on limited modern data and may not provide an accurate or comprehensive view of the future. Therefore, this dissertation investigates coastal stratigraphic records to determine long-term past trends of these presses and pulses so that researchers, stakeholders, and policy makers can use them to enact strategies to mitigate damages from worsening impacts.
This dissertation includes an investigation of stratigraphic microplastic pollution in Louisiana, the first such study in North America. Importantly, this study confirmed that rates of microplastic pollution in the stratigraphy have increased commensurately with increased global plastic production. In addition to Louisiana, this dissertation utilizes sedimentary, geochemical, and anthropogenic proxies from sediment cores and surface samples from Puerto Rico to identify long-term trends in hurricane activity and microplastic deposition in the northern Caribbean. Sediment cores from southwestern Puerto Rico suggest that the region has been in an active hurricane period since the mid-20th century with a prior ~1000 year-long quiescent period, similar to findings from other regions in the Greater Antilles. Additionally, microplastic abundance in the stratigraphy across Puerto Rico increases similarly to the Louisiana stratigraphy. Notably, high concentrations of microplastics occurred within inferred hurricane deposits, suggesting a relationship between hurricane occurrence and microplastic deposition. This association implies that microplastic may be able to be used as a novel proxy for recent hurricane deposits in paleotempestology. Furthermore, stratigraphic and surface samples suggest that microplastic is sequestered in certain coastal substrates like mangrove forest muds and wrack lines. These substrates and the surrounding environment may act like a microplastic sink, permanently sequestering microplastic in deep sediments (those that are deeper than 6 cm). While impacts from hurricanes and microplastic pollution are forecast to worsen in the coming decades, this dissertation aims to provide data that can be used to identify the most vulnerable regions and hopefully mitigate some future damage.
Date
8-23-2024
Recommended Citation
Culligan, Nicholas T., "Coastal sedimentary records of extreme events and human activity: Examples from hurricanes and microplastics" (2024). LSU Doctoral Dissertations. 6589.
https://repository.lsu.edu/gradschool_dissertations/6589
Committee Chair
Liu, Kam-biu
Included in
Atmospheric Sciences Commons, Climate Commons, Environmental Health and Protection Commons, Geology Commons, Meteorology Commons, Oceanography Commons, Other Environmental Sciences Commons, Sedimentology Commons, Sustainability Commons