Relating Physical Chemistry Parameters in Hypersaline Brines From Western Australia, The Antarctic Dry Valleys and a Southern California Saltern

Author

• Thomas J. Bornholdt, Louisiana State University and Agricultural and Mechanical CollegeFollow

Semester of Graduation

Spring 2026

Degree

Master of Science (MS)

Department

Geology and Geophysics

Document Type

Thesis

Abstract

The physical and chemical properties of seawater are well constrained and are readily measurable in bodies of freshwater and even sea water, but their behavior in hypersaline brines is less well quantified. The lakes of western Australia are mostly dominated by NaCl salts except for Lake Gounter, which is MgCl₂ dominant. Similarly, the lakes in the McMurdo Dry Valleys are also NaCl dominated except for Don Juan Pond, which is CaCl₂ dominant. South Bay Salt Works ponds are either NaCl or MgCl₂ brines. Ca(ClO₄)₂ is one of the major salts found in Martian regolith and can deliquesce to create supersaturated brines. How physical-chemical properties and measurement differ between different brines of varying composition remains understudied. In this study, pure laboratory brines of NaCl, MgCl₂, CaCl_2, and Ca(ClO₄)₂ were generated across a 30-point serial dilution from saturation to dilute conditions.  Dissolved oxygen, density, Total Dissolved Solids (TDS), pH, water activity, conductivity, refractive index, and ORP were measured and compared to natural hypersaline brines from Western Australia, the McMurdo Dry Valleys in Antarctica, and South Bay Salt Works in southern California. PhreeQC modeling was used to evaluate theoretical behavior in NaCl, MgCl₂, CaCl₂ systems. Results demonstrate that conductivity exhibits composition-dependent and nonlinear behavior at higher ionic strength, limiting its reliability in estimating TDS in hypersaline systems. In contrast, the strong relationship between density and TDS is independent of salt type. Water activity changes with the varying salinity and salt type, indicating that TDS does not imply equivalent thermodynamic water availability or biological potential. Dissolved oxygen solubility varies moderately among salts at 25°C but exhibits greater divergence at 0°C. The relationship between various properties in brines is explored in this study and implications considered for eventual in situ measurements on extraterrestrial bodies in our Solar System where brines may exist.

Date

3-9-2026

Recommended Citation

Bornholdt, Thomas J., "Relating Physical Chemistry Parameters in Hypersaline Brines From Western Australia, The Antarctic Dry Valleys and a Southern California Saltern" (2026). LSU Master's Theses. 6285.
https://repository.lsu.edu/gradschool_theses/6285

Committee Chair

Doran, Peter T.

LSU Acknowledgement

1

LSU Accessibility Acknowledgment

1