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

Jasechko, S; Perrone, D; Befus, KM; Bayani Cardenas, M; Ferguson, G; Gleeson, T; Luijendijk, E; ... Kirchner, JW; + view all (2017) Global aquifers dominated by fossil groundwaters but wells vulnerable to modern contamination. Nature Geoscience , 10 pp. 425-429. 10.1038/ngeo2943. Green open access

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Abstract

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.

Type: Article
Title: Global aquifers dominated by fossil groundwaters but wells vulnerable to modern contamination
Open access status: An open access version is available from UCL Discovery
DOI: 10.1038/ngeo2943
Publisher version: http://dx.doi.org/10.1038/ngeo2943
Language: English
Additional information: This version is the author accepted manuscript. For information on re-use, please refer to the publisher’s terms and conditions.
Keywords: Geochemistry, Hydrogeology, Hydrology, Water resources
UCL classification: UCL
UCL > Provost and Vice Provost Offices > UCL SLASH
UCL > Provost and Vice Provost Offices > UCL SLASH > Faculty of S&HS
UCL > Provost and Vice Provost Offices > UCL SLASH > Faculty of S&HS > Dept of Geography
URI: https://discovery.ucl.ac.uk/id/eprint/1556316
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