Date of Award

Fall 2020

Degree Type

Masters Thesis

Degree Name

Master of Science (MS)

School

Ocean Science and Engineering

Committee Chair

Alan Shiller

Committee Chair School

Ocean Science and Engineering

Committee Member 2

Christopher Hayes

Committee Member 2 School

Ocean Science and Engineering

Committee Member 3

Davin Wallace

Committee Member 3 School

Ocean Science and Engineering

Abstract

This thesis assesses the role of submarine groundwater discharge (SGD) in St. Louis Bay, Mississippi. Located along the northern Gulf of Mexico, St. Louis Bay (SLB) is a semi-enclosed bay that is important to the local area for recreation and tourism. SGD is the movement of any water into the water column across the sediment-water interface. In coastal environments, SGD can be a source of a variety of substances including nutrients and pollutants. In this study, a steady state mass balance approach was used to quantify SGD flux for SLB using 223Ra, 224Ra, and Ba. Using the water volume flux data calculated from the mass balances and groundwater endmembers for CH4, NO3, NO2, NH4, PO4, and SiO3, fluxes from SGD of these select substances were calculated. It was found that the average water volume flux of SGD was 5.3 · 105 m3 d-1 and delivers approximately 1300 mol d-1 during the sampling period. SGD was also found to be a significant source of NO3 (17-60 kmol d-1) and PO4 (12-42 kmol d-1) into the bay. Since nutrient loading is a concern in St. Louis Bay for eutrophication, understanding the role SGD plays is an important consideration for managing this environmental issue.

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