Earth and Planetary Sciences ETDs

Publication Date

Summer 7-29-2025

Abstract

In arid environments, maintaining water balance can be more critical for survival than obtaining food. As droughts intensify, understanding how animals manage body water is essential. Triple oxygen isotope analysis provides a novel way to trace water sources in animals, distinguishing contributions from free water, food-derived oxygen, and atmospheric O2. We developed an equilibration method using CO2–H2O oxygen exchange and measured δ’18O and Δ’17O values via tunable infrared laser direct spectroscopy (TILDAS). Validated against traditional fluorination methods, this technique enables streamlined analysis of whole blood and plant samples. Applied to desert-dwelling rodents (Heteromyidae), our method revealed seasonal shifts in water use, with free water inputs closely tracking precipitation, likely via seed rehydration or vapor uptake in burrows. Leaf water data exposed limitations in existing body water models, underscoring the need for ground truthing 17O-based body water models for paleoclimate reconstruction with modern systems.

Degree Name

Earth and Planetary Sciences

Level of Degree

Masters

Department Name

Department of Earth and Planetary Sciences

First Committee Member (Chair)

Zachary D. Sharp

Second Committee Member

Seth D. Newsome

Third Committee Member

Marisa N. Repasch

Keywords

triple oxygen isotopes, body water modeling, leaf water fractionation, Sevilleta Wildlife Refuge, tunable infrared laser direct spectroscopy

Document Type

Thesis

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