Critical zone (bio)geochemical reactivity and hydrologic transport recorded by the stable lithium isotope ratios of fluids draining upland watersheds
Golla, Jon Kenneth Kabigting
This item is only available for download by members of the University of Illinois community. Students, faculty, and staff at the U of I may log in with your NetID and password to view the item. If you are trying to access an Illinois-restricted dissertation or thesis, you can request a copy through your library's Inter-Library Loan office or purchase a copy directly from ProQuest.
Permalink
https://hdl.handle.net/2142/121342
Description
Title
Critical zone (bio)geochemical reactivity and hydrologic transport recorded by the stable lithium isotope ratios of fluids draining upland watersheds
Author(s)
Golla, Jon Kenneth Kabigting
Issue Date
2023-07-11
Director of Research (if dissertation) or Advisor (if thesis)
Druhan, Jennifer L
Doctoral Committee Chair(s)
Druhan, Jennifer L
Committee Member(s)
Conroy, Jessica L
Johnson, Thomas M
Bouchez, Julien
Department of Study
Earth Sci & Environmental Chng
Discipline
Geology
Degree Granting Institution
University of Illinois at Urbana-Champaign
Degree Name
Ph.D.
Degree Level
Dissertation
Keyword(s)
Critical Zone
hydrology
biogeochemistry
weathering
isotopes
Abstract
The interaction between water and silicate minerals regulates landscape functioning (e.g., soil formation, nutrient export, CO2 drawdown), shaping the Critical Zone or the region of the Earth surface between the top of trees and the base of aquifers. Such biogeochemical processes that sustain this near-surface environment are typically inferred from streamflow chemistry. However, the extent to which this stream signal can represent the pathways fluid transits and the fluid-rock reactions that occur during flow remains unresolved. I address this knowledge gap by (1) establishing an understanding of how fluid-rock reactivity initiates and spatially propagates in the Critical Zone followed by (2) an investigation of transient perturbations that reveal the coupling between hydrologic transport and reactivity during storms. This stepwise approach is applied to two small, pristine upland catchments using reactive transport modeling and lithium (Li) as a tracer given the sensitivity of its isotopes (7Li and 6Li) to fluid-rock reactivity. Using the highly-instrumented Elder Creek catchment in northern California, I first demonstrate that subsurface fluid contributing to streamflow can be distinguished by lithium isotope signatures that resemble unique compartments of a weathering profile (i.e., soil, weathered bedrock, and fresh bedrock). Then, I show that streamflow Li during storms records shifts in flow rates and the expansion of the footprint of subsurface fluid-rock reactivity as a result of a rise in the groundwater table. The conceptual framework established by this work is then translated to the relatively less characterized Sapine Creek catchment in Mont-Lozère, southern France. Here, I simulate the development of the weathering profile to reveal that the reactivity underlying unique streamflow Li signatures are due to high retention of weathering byproducts and significant input of exogenous dust. Finally, I leverage a novel set of streamflow Li observations from two storm events that are preceded by unique background hydrological conditions (i.e., dry vs. wet) to show how reactive fluids are routed in the Critical Zone during infiltration and discharge. These findings contribute to a greater understanding of landscape and ecosystem biogeochemical response during periods of transient hydrological disturbance, which is critical given that the occurrence of such extreme events is predicted to intensify in the future.
Use this login method if you
don't
have an
@illinois.edu
email address.
(Oops, I do have one)
IDEALS migrated to a new platform on June 23, 2022. If you created
your account prior to this date, you will have to reset your password
using the forgot-password link below.
