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Isotopic Fractionation of U in Rocks Reflecting Redox Conditions around a Groundwater Flow Route

Published online by Cambridge University Press:  21 March 2011

Juhani Suksi  and
Kari Rasilainen
Juhani Suksi
Affiliation:
Laboratory of Radiochemistry, University of Helsinki, Finland
Kari Rasilainen
Affiliation:
VTT Energy, Espoo, Finland
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Abstract

Abstract; Low 234U/238U activity ratios observed in rock and mineral samples were scrutinized. U isotope fractionation leading to 234U depletion (234U/238U<1) in rocks appears to be linked to changes in redox conditions. The fractionation takes place as selective chemical release dominates over direct physical μ recoil. This preferential 234U release depends on the valence contrast between the U isotopes, 238U occurring in +4 form and ingrown 234U, due to oxidizing microenvironment, in +6 form. Observed U isotopic fractionation combined with other uranium series disequilibrium measurements provides a tool for locating redox fronts formed as a result low temperature rock-groundwater interaction.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 663: Symposium – Scientific Basis for Nuclear Waste management XXIV , 2000 , 961
Copyright
Copyright © Materials Research Society 2001

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References

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