Antecedent Hydrologic Conditions Reflected in Stream Lithium Isotope Ratios During Storms

Jon K. Golla, Julien Bouchez, Jennifer L. Druhan

Research output: Contribution to journalArticlepeer-review

Abstract

Antecedent hydrological conditions are recorded through the evolution of dissolved lithium isotope signatures ((Formula presented.) Li) by juxtaposing two storm events in an upland watershed subject to a Mediterranean climate. Discharge and (Formula presented.) Li are negatively correlated in both events, but mean (Formula presented.) Li ratios and associated ranges of variation are distinct between them. We apply a previously developed reactive transport model (RTM) for the site to these event-scale flow perturbations, but observed shifts in stream (Formula presented.) Li are not reproduced. To reconcile the stability of the subsurface solute weathering profile with our observations of dynamic stream (Formula presented.) Li signatures, we couple the RTM to a distribution of fluid transit times that evolve based on storm hydrographs. The approach guides appropriate flux-weighting of fluid from the RTM over a range of flow path lengths, or equivalently fluid residence times. This flux-weighted RTM approach accurately reproduces dynamic storm (Formula presented.) Li-discharge patterns distinguished by the antecedent conditions of the watershed.

Original languageEnglish (US)
Article numbere2024GL109624
JournalGeophysical Research Letters
Volume51
Issue number17
DOIs
StatePublished - Sep 16 2024

Keywords

  • critical zone
  • geochemistry
  • hydrology
  • lithium isotopes
  • solute export
  • storms

ASJC Scopus subject areas

  • Geophysics
  • General Earth and Planetary Sciences

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