Global aquifers dominated by fossil groundwaters but wells vulnerable to modern contamination

Scott Jasechko*, Debra Perrone, Kevin M. Befus, M. Bayani Cardenas, Grant Ferguson, Tom Gleeson, Elco Luijendijk, Jeffrey J. McDonnell, Richard G. Taylor, Yoshihide Wada, James W. Kirchner

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

103 Citations (Scopus)


The vulnerability of groundwater to contamination is closely related to its age. Groundwaters that infiltrated prior to the Holocene have been documented in many aquifers and are widely assumed to be unaffected by modern contamination. However, the global prevalence of these ‘fossil’ groundwaters and their vulnerability to modern-era pollutants remain unclear. Here we analyse groundwater carbon isotope data (12C, 13C, 14C) from 6,455 wells around the globe. We show that fossil groundwaters comprise a large share (42–85%) of total aquifer storage in the upper 1 km of the crust, and the majority of waters pumped from wells deeper than 250 m. However, half of the wells in our study that are dominated by fossil groundwater also contain detectable levels of tritium, indicating the presence of much younger, decadal-age waters and suggesting that contemporary contaminants may be able to reach deep wells that tap fossil aquifers. We conclude that water quality risk should be considered along with sustainable use when managing fossil groundwater resources.

Original languageEnglish
Pages (from-to)425-429
Number of pages5
JournalNature Geoscience
Early online date25 Apr 2017
Publication statusPublished - Jun 2017

ASJC Scopus subject areas

  • Earth and Planetary Sciences(all)


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