Relic Groundwater and Prolonged Drought Confound Interpretations of Water Sustainability and Lithium Extraction in Arid Lands

Demand for lithium for batteries is growing rapidly with the global push to decarbonize energy systems. The Salar de Atacama, Chile holds ∼42% of the planet's reserves in the form of brine hosted in massive evaporite aquifers. The mining of these brines and associated freshwater use has raised concerns over the environmental responsibility of lithium extraction, yet large uncertainties remain regarding fundamental aspects of governing hydrological processes in these environments. This incomplete understanding has led to the perpetuation of misconceptions about what constitutes sustainable or renewable water use and therefore what justifies responsible allocation. We present an integrated hydrological assessment using tritium and stable oxygen, and hydrogen isotopes paired with remotely sensed and terrestrial hydroclimate data to define unique sources of water distinguished by residence time, physical characteristics, and connectivity to modern climate. Our results describe the impacts of prolonged drought on surface and groundwaters and demonstrate that nearly all inflow to the basin is composed of water recharged >65 years ago. Still, modern precipitation is critical to sustaining important wetlands around the salar. Recent large rain events have increased surface water and vegetation extents and terrestrial water storage while mining-related water withdrawals have continued. As we show, poor conceptualizations of these complex hydrological systems have perpetuated the misallocation of water and the misattribution of impacts. These fundamental issues apply to arid regions globally. Our new framework for hydrological assessment in these basins moves beyond calculating gross inputs-outputs at a steady state to include all compartmentalized stores that constitute “modern” budgets.

Citation

Brendan J. Moran, Dr. David Boutt, Sarah V. McKnight, Jordan Jenckes, Lee Ann Munk, Daniel Corkran, and Alexander Kirshen. Relic Groundwater and Prolonged Drought Confound Interpretations of Water Sustainability and Lithium Extraction in Arid Lands,” Earth's Future, July 2022. DOI: https://doi.org/10.1029/2021EF002555.
© 2022 The Authors. Earth's Future published by Wiley Periodicals LLC on behalf of American Geophysical Union. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

Authors

Brendan J. Moran
Dr. David Boutt
Sarah V. McKnight
Jordan Jenckes
Lee Ann Munk
Daniel Corkran
Alexander Kirshen