skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Continental degassing of 4He by surficial discharge of deep groundwater

Abstract

Radiogenic He-4 is produced by the decay of uranium and thorium in the Earths mantle and crust. From here, it is degassed to the atmosphere(1-5) and eventually escapes to space(1,5,6). Assuming that all of the He-4 produced is degassed, about 70% of the total He-4 degassed from Earth comes from the continental crust(2,-5,7). However, the outgoing flux of crustal He-4 has not been directly measured at the Earths surface(2) and the migration pathways are poorly understood(2-4,7,8). Here we present measurements of helium isotopes and the long-lived cosmogenic radio-isotope Kr-81 in the deep, continental-scale Guarani aquifer in Brazil and show that crustal He-4 reaches the atmosphere primarily by the surficial discharge of deep groundwater. We estimate that He-4 in Guarani groundwater discharge accounts for about 20% of the assumed global flux from continental crust, and that other large aquifers may account for about 33%. Old groundwater ages suggest that He-4 in the Guarani aquifer accumulates over half- to one-million-year timescales. We conclude that He-4 degassing from the continents is regulated by groundwater discharge, rather than episodic tectonic events, and suggest that the assumed steady state between crustal production and degassing of He-4, and its resulting atmospheric residence time, should be re-examined

Authors:
; ; ; ; ; ; ; ; ; ; ;
Publication Date:
Research Org.:
Argonne National Lab. (ANL), Argonne, IL (United States)
Sponsoring Org.:
USDOE Office of Science - Office of Nuclear Physics
OSTI Identifier:
1412699
DOE Contract Number:  
AC02-06CH11357
Resource Type:
Journal Article
Journal Name:
Nature Geoscience
Additional Journal Information:
Journal Volume: 8; Journal Issue: 1; Journal ID: ISSN 1752-0894
Publisher:
Nature Publishing Group
Country of Publication:
United States
Language:
English
Subject:
54 ENVIRONMENTAL SCIENCES

Citation Formats

Aggarwal, Pradeep K., Matsumoto, Takuya, Sturchio, Neil C., Chang, Hung K., Gastmans, Didier, Araguas-Araguas, Luis J., Jiang, Wei, Lu, Zheng-Tian, Mueller, Peter, Yokochi, Reika, Purtschert, Roland, and Torgersen, Thomas. Continental degassing of 4He by surficial discharge of deep groundwater. United States: N. p., 2014. Web. doi:10.1038/ngeo2302.
Aggarwal, Pradeep K., Matsumoto, Takuya, Sturchio, Neil C., Chang, Hung K., Gastmans, Didier, Araguas-Araguas, Luis J., Jiang, Wei, Lu, Zheng-Tian, Mueller, Peter, Yokochi, Reika, Purtschert, Roland, & Torgersen, Thomas. Continental degassing of 4He by surficial discharge of deep groundwater. United States. doi:10.1038/ngeo2302.
Aggarwal, Pradeep K., Matsumoto, Takuya, Sturchio, Neil C., Chang, Hung K., Gastmans, Didier, Araguas-Araguas, Luis J., Jiang, Wei, Lu, Zheng-Tian, Mueller, Peter, Yokochi, Reika, Purtschert, Roland, and Torgersen, Thomas. Mon . "Continental degassing of 4He by surficial discharge of deep groundwater". United States. doi:10.1038/ngeo2302.
@article{osti_1412699,
title = {Continental degassing of 4He by surficial discharge of deep groundwater},
author = {Aggarwal, Pradeep K. and Matsumoto, Takuya and Sturchio, Neil C. and Chang, Hung K. and Gastmans, Didier and Araguas-Araguas, Luis J. and Jiang, Wei and Lu, Zheng-Tian and Mueller, Peter and Yokochi, Reika and Purtschert, Roland and Torgersen, Thomas},
abstractNote = {Radiogenic He-4 is produced by the decay of uranium and thorium in the Earths mantle and crust. From here, it is degassed to the atmosphere(1-5) and eventually escapes to space(1,5,6). Assuming that all of the He-4 produced is degassed, about 70% of the total He-4 degassed from Earth comes from the continental crust(2,-5,7). However, the outgoing flux of crustal He-4 has not been directly measured at the Earths surface(2) and the migration pathways are poorly understood(2-4,7,8). Here we present measurements of helium isotopes and the long-lived cosmogenic radio-isotope Kr-81 in the deep, continental-scale Guarani aquifer in Brazil and show that crustal He-4 reaches the atmosphere primarily by the surficial discharge of deep groundwater. We estimate that He-4 in Guarani groundwater discharge accounts for about 20% of the assumed global flux from continental crust, and that other large aquifers may account for about 33%. Old groundwater ages suggest that He-4 in the Guarani aquifer accumulates over half- to one-million-year timescales. We conclude that He-4 degassing from the continents is regulated by groundwater discharge, rather than episodic tectonic events, and suggest that the assumed steady state between crustal production and degassing of He-4, and its resulting atmospheric residence time, should be re-examined},
doi = {10.1038/ngeo2302},
journal = {Nature Geoscience},
issn = {1752-0894},
number = 1,
volume = 8,
place = {United States},
year = {2014},
month = {12}
}

Works referenced in this record:

Tracer applications of noble gas radionuclides in the geosciences
journal, November 2014


Prodigious degassing of a billion years of accumulated radiogenic helium at Yellowstone
journal, February 2014

  • Lowenstern, J. B.; Evans, W. C.; Bergfeld, D.
  • Nature, Vol. 506, Issue 7488
  • DOI: 10.1038/nature12992

Lower Groundwater 14 C Age by Atmospheric CO 2 Uptake During Sampling and Analysis : P.K. Aggarwal et al. Ground Water xx, no. x: xx-xx
journal, August 2013

  • Aggarwal, Pradeep K.; Araguas-Araguas, Luis; Choudhry, Manzoor
  • Groundwater, Vol. 52, Issue 1
  • DOI: 10.1111/gwat.12110

Tracing Fluid Origin, Transport and Interaction in the Crust
journal, January 2002

  • Ballentine, C. J.; Burgess, R.; Marty, B.
  • Reviews in Mineralogy and Geochemistry, Vol. 47, Issue 1
  • DOI: 10.2138/rmg.2002.47.13

A paleotemperature record derived from dissolved noble gases in groundwater of the Aquia Aquifer (Maryland, USA)
journal, March 2002


Heat and helium in the Earth
journal, December 1983

  • O'Nions, R. K.; Oxburgh, E. R.
  • Nature, Vol. 306, Issue 5942
  • DOI: 10.1038/306429a0