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Crustal Groundwater Volumes Greater than Previously Thought
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  • Grant Ferguson,
  • Jennifer McIntosh,
  • Oliver Warr,
  • Barbara Sherwood Lollar,
  • Chris J Ballentine,
  • James S. Famiglietti,
  • Ji-Hyun Kim,
  • Joseph Michalski,
  • John Mustard,
  • Jesse D Tarnas,
  • Jeffrey J. McDonnell
Grant Ferguson
University of Saskatchewan, University of Saskatchewan

Corresponding Author:[email protected]

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Jennifer McIntosh
University of Arizona, University of Arizona
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Oliver Warr
University of Toronto, University of Toronto
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Barbara Sherwood Lollar
University of Toronto, University of Toronto
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Chris J Ballentine
University of Oxford, University of Oxford
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James S. Famiglietti
University of Saskatchewan, University of Saskatchewan
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Ji-Hyun Kim
University of Arizona, University of Arizona
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Joseph Michalski
University of Hong Kong, University of Hong Kong
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John Mustard
Department of Earth, Environmental and Planetary Sciences, Department of Earth, Environmental and Planetary Sciences
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Jesse D Tarnas
Jet Propulsion Laboratory, Jet Propulsion Laboratory
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Jeffrey J. McDonnell
University of Saskatchewan, University of Saskatchewan
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Abstract

Global groundwater volumes in the upper 2 km of the Earth’s continental crust – critical for water security – are well estimated. Beyond these depths, a vast body of largely saline and non-potable groundwater exists down to at least 10 km —a volume that has not yet been quantified reliably at the global scale. Here, we estimate the amount of groundwater present in the upper 10 km of the Earth’s continental crust by examining the distribution of sedimentary and cratonic rocks with depth and applying porosity-depth relationships. We demonstrate that groundwater in the 2-10 km zone (what we call ‘deep groundwater’) has a volume comparable to that of groundwater in the upper 2 km of the Earth’s crust. These new estimates make groundwater the largest continental reservoir of water, ahead of ice sheets, provide a basis to quantify geochemical cycles, and constrain the potential for large-scale isolation of waste fluids.
28 Aug 2021Published in Geophysical Research Letters volume 48 issue 16. 10.1029/2021GL093549