Continental degassing of He-4 by surficial discharge of deep groundwater

dc.contributorIAEA
dc.contributorUniv Delaware
dc.contributorUniversidade Estadual Paulista (Unesp)
dc.contributorArgonne Natl Lab
dc.contributorUniv Chicago
dc.contributorUniv Bern
dc.contributorNatl Sci Fdn
dc.creatorAggarwal, Pradeep K.
dc.creatorMatsumoto, Takuya
dc.creatorSturchio, Neil C.
dc.creatorChang, Hung K. [UNESP]
dc.creatorGastmans, Didier [UNESP]
dc.creatorAraguas-Araguas, Luis J.
dc.creatorJiang, Wei
dc.creatorLu, Zheng-Tian
dc.creatorMueller, Peter
dc.creatorYokochi, Reika
dc.creatorPurtschert, Roland
dc.creatorTorgersen, Thomas
dc.date2015-10-21T20:17:16Z
dc.date2015-10-21T20:17:16Z
dc.date2015-01-01
dc.date.accessioned2023-09-12T06:47:46Z
dc.date.available2023-09-12T06:47:46Z
dc.identifierhttp://www.nature.com/ngeo/journal/v8/n1/full/ngeo2302.html
dc.identifierNature Geoscience, v. 8, n. 1, p. 35-39, 2015.
dc.identifier1752-0894
dc.identifierhttp://hdl.handle.net/11449/129057
dc.identifier10.1038/NGEO2302
dc.identifierWOS:000346825000012
dc.identifier1989662459244838
dc.identifier.urihttps://repositorioslatinoamericanos.uchile.cl/handle/2250/8778398
dc.descriptionRadiogenic 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.
dc.descriptionDOE, Office of Nuclear Physics
dc.descriptionNSF
dc.descriptionIAEA, Isotope Hydrol Sect, A-1400 Vienna, Austria
dc.descriptionUniv Delaware, Dept Geol Sci, Newark, DE 19716 USA
dc.descriptionUniv Estadual Paulista, UNESP, CEA, BR-13506900 Rio Claro, SP, Brazil
dc.descriptionUniv Estadual Paulista, UNESP, LEBAC, BR-13506900 Rio Claro, SP, Brazil
dc.descriptionArgonne Natl Lab, Div Phys, Argonne, IL 60439 USA
dc.descriptionUniv Chicago, Dept Phys, Chicago, IL 60637 USA
dc.descriptionUniv Chicago, Enrico Fermi Inst, Chicago, IL 60637 USA
dc.descriptionUniv Chicago, Dept Geophys Sci, Chicago, IL 60637 USA
dc.descriptionUniv Bern, Inst Phys, CH-3012 Bern, Switzerland
dc.descriptionNatl Sci Fdn, Arlington, VA 22230 USA
dc.descriptionUniv Estadual Paulista, UNESP, CEA, BR-13506900 Rio Claro, SP, Brazil
dc.descriptionUniv Estadual Paulista, UNESP, LEBAC, BR-13506900 Rio Claro, SP, Brazil
dc.descriptionDOE, Office of Nuclear Physics: DE-AC02-06CH11357
dc.descriptionNSF: EAR-0651161
dc.format35-39
dc.languageeng
dc.publisherNature Publishing Group
dc.relationNature Geoscience
dc.relation14.391
dc.relation6,752
dc.rightsAcesso restrito
dc.sourceWeb of Science
dc.titleContinental degassing of He-4 by surficial discharge of deep groundwater
dc.typeArtigo


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