Field Application of 238U/235U Measurements to Detect Reoxidation and Mobilization of U(IV)

Noah E. Jemison, Alyssa E. Shiel, Thomas Martin Johnson, Craig Campbell Lundstrom, Philip E. Long, Kenneth H. Williams

Research output: Contribution to journalArticle

Abstract

Biostimulation to induce reduction of soluble U(VI) to relatively immobile U(IV) is an effective strategy for decreasing aqueous U(VI) concentrations in contaminated groundwater systems. If oxidation of U(IV) occurs following the biostimulation phase, U(VI) concentrations increase, challenging the long-term effectiveness of this technique. However, detecting U(IV) oxidation through dissolved U concentrations alone can prove difficult in locations with few groundwater wells to track the addition of U to a mass of groundwater. We propose the 238U/235U ratio of aqueous U as an independent, reliable tracer of U(IV) remobilization via oxidation or mobilization of colloids. Reduction of U(VI) produces 238U-enriched U(IV), whereas remobilization of solid U(IV) should not induce isotopic fractionation. The incorporation of remobilized U(IV) with a high 238U/235U ratio into the aqueous U(VI) pool produces an increase in 238U/235U of aqueous U(VI). During several injections of nitrate to induce U(IV) oxidation, 238U/235U consistently increased, suggesting 238U/235U is broadly applicable for detecting mobilization of U(IV).

Original languageEnglish (US)
Pages (from-to)3422-3430
Number of pages9
JournalEnvironmental Science and Technology
Volume52
Issue number6
DOIs
StatePublished - Mar 20 2018

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mobilization
Groundwater
oxidation
Oxidation
remobilization
groundwater
isotopic fractionation
Colloids
Fractionation
colloid
Nitrates
tracer
nitrate
well

ASJC Scopus subject areas

  • Chemistry(all)
  • Environmental Chemistry

Cite this

Field Application of 238U/235U Measurements to Detect Reoxidation and Mobilization of U(IV). / Jemison, Noah E.; Shiel, Alyssa E.; Johnson, Thomas Martin; Lundstrom, Craig Campbell; Long, Philip E.; Williams, Kenneth H.

In: Environmental Science and Technology, Vol. 52, No. 6, 20.03.2018, p. 3422-3430.

Research output: Contribution to journalArticle

Jemison, Noah E. ; Shiel, Alyssa E. ; Johnson, Thomas Martin ; Lundstrom, Craig Campbell ; Long, Philip E. ; Williams, Kenneth H. / Field Application of 238U/235U Measurements to Detect Reoxidation and Mobilization of U(IV). In: Environmental Science and Technology. 2018 ; Vol. 52, No. 6. pp. 3422-3430.
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