Electronic Theses and Dissertations

Date

2024

Document Type

Thesis

Degree Name

Master of Science

Department

Earth Sciences

Committee Chair

Daniel Larsen

Committee Member

Scott Schoefernacker

Committee Member

Deborah Leslie

Committee Member

Brian Waldron

Abstract

Geochemical data from 2009-2023 for production wells in Shelby County, Tennessee, were analyzed to determine the origin of discrepancies in sulfur hexafluoride (SF6) results in relationship to other tracers and hydrogeologic characteristics of sampled wells. This study proposes three potential origins for the discrepancies: modern SF6 contamination introduced during sampling, contributions of terrigenic SF6 formation, and groundwater re-equilibration with modern air in the unsaturated zone. The results suggest contamination with modern air during sampling is significant in some settings. An airtight sampling method was developed and shown to be successful in reducing introduction of modern air during sampling. The results suggest that terrigenic SF6 may affect samples from wells in proximity to faults and unconfined conditions in wells may introduce modern air due to water re-equilibration. SF6 sample results from urban areas should be carefully analyzed with respect to well conditions, proximity to faults, and proximity to local SF6 sources.

Comments

Data is provided by the student.

Library Comment

Dissertation or thesis originally submitted to ProQuest.

Notes

Open Access

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