Details
| Original language | English |
|---|---|
| Pages (from-to) | 6595-6604 |
| Number of pages | 10 |
| Journal | Environmental Science and Technology |
| Volume | 58 |
| Issue number | 15 |
| Early online date | 4 Apr 2024 |
| Publication status | Published - 16 Apr 2024 |
Abstract
Meaningful interpretation of U isotope measurements relies on unraveling the impact of reduction mechanisms on the isotopic fractionation. Here, the isotope fractionation of hexavalent U [U(VI)] was investigated during its reductive mineralization by magnetite to intermediate pentavalent U [U(V)] and ultimately tetravalent U [U(IV)]. As the reaction proceeded, the remaining aqueous phase U [containing U(VI) and U(V)] systematically carried light isotopes, whereas in the bicarbonate-extracted solution [containing U(VI) and U(V)], the δ238U values varied, especially when C/C0 approached 0. This variation was interpreted as reflecting the variable relative contribution of unreduced U(VI) (δ238U < 0‰) and bicarbonate-extractable U(V) (δ238U > 0‰). The solid remaining after bicarbonate extraction included unextractable U(V) and U(IV), for which the δ238U values consistently followed the same trend that started at 0.3-0.5‰ and decreased to ∼0‰. The impact of PIPES buffer on isotopic fractionation was attributed to the variable abundance of U(V) in the aqueous phase. A few extremely heavy bicarbonate-extracted δ238U values were due to mass-dependent fractionation resulting from several hypothesized mechanisms. The results suggest the preferential accumulation of the heavy isotope in the reduced species and the significant influence of U(V) on the overall isotopic fractionation, providing insight into the U isotope fractionation behavior during its abiotic reduction process.
Keywords
- isotope fractionation, pentavalent uranium, redox tracer, uranium remediation
ASJC Scopus subject areas
- Chemistry(all)
- Environmental Science(all)
- Environmental Chemistry
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In: Environmental Science and Technology, Vol. 58, No. 15, 16.04.2024, p. 6595-6604.
Research output: Contribution to journal › Article › Research › peer review
}
TY - JOUR
T1 - Pentavalent U Reactivity Impacts U Isotopic Fractionation during Reduction by Magnetite
AU - Pan, Zezhen
AU - Loreggian, Luca
AU - Roebbert, Yvonne
AU - Bartova, Barbora
AU - Hunault, Myrtille O.J.Y.
AU - Weyer, Stefan
AU - Bernier-Latmani, Rizlan
N1 - Funding Information: The work at Fudan received supports from the National Natural Science Foundation of China (42107228) and the Shanghai Pujiang Program (21PJ1401000), and the work at EPFL was supported by Swiss National Science Foundation Grant 200021E-164209 and European Research Council Consolidator Grant 725675 (UNEARTH).
PY - 2024/4/16
Y1 - 2024/4/16
N2 - Meaningful interpretation of U isotope measurements relies on unraveling the impact of reduction mechanisms on the isotopic fractionation. Here, the isotope fractionation of hexavalent U [U(VI)] was investigated during its reductive mineralization by magnetite to intermediate pentavalent U [U(V)] and ultimately tetravalent U [U(IV)]. As the reaction proceeded, the remaining aqueous phase U [containing U(VI) and U(V)] systematically carried light isotopes, whereas in the bicarbonate-extracted solution [containing U(VI) and U(V)], the δ238U values varied, especially when C/C0 approached 0. This variation was interpreted as reflecting the variable relative contribution of unreduced U(VI) (δ238U < 0‰) and bicarbonate-extractable U(V) (δ238U > 0‰). The solid remaining after bicarbonate extraction included unextractable U(V) and U(IV), for which the δ238U values consistently followed the same trend that started at 0.3-0.5‰ and decreased to ∼0‰. The impact of PIPES buffer on isotopic fractionation was attributed to the variable abundance of U(V) in the aqueous phase. A few extremely heavy bicarbonate-extracted δ238U values were due to mass-dependent fractionation resulting from several hypothesized mechanisms. The results suggest the preferential accumulation of the heavy isotope in the reduced species and the significant influence of U(V) on the overall isotopic fractionation, providing insight into the U isotope fractionation behavior during its abiotic reduction process.
AB - Meaningful interpretation of U isotope measurements relies on unraveling the impact of reduction mechanisms on the isotopic fractionation. Here, the isotope fractionation of hexavalent U [U(VI)] was investigated during its reductive mineralization by magnetite to intermediate pentavalent U [U(V)] and ultimately tetravalent U [U(IV)]. As the reaction proceeded, the remaining aqueous phase U [containing U(VI) and U(V)] systematically carried light isotopes, whereas in the bicarbonate-extracted solution [containing U(VI) and U(V)], the δ238U values varied, especially when C/C0 approached 0. This variation was interpreted as reflecting the variable relative contribution of unreduced U(VI) (δ238U < 0‰) and bicarbonate-extractable U(V) (δ238U > 0‰). The solid remaining after bicarbonate extraction included unextractable U(V) and U(IV), for which the δ238U values consistently followed the same trend that started at 0.3-0.5‰ and decreased to ∼0‰. The impact of PIPES buffer on isotopic fractionation was attributed to the variable abundance of U(V) in the aqueous phase. A few extremely heavy bicarbonate-extracted δ238U values were due to mass-dependent fractionation resulting from several hypothesized mechanisms. The results suggest the preferential accumulation of the heavy isotope in the reduced species and the significant influence of U(V) on the overall isotopic fractionation, providing insight into the U isotope fractionation behavior during its abiotic reduction process.
KW - isotope fractionation
KW - pentavalent uranium
KW - redox tracer
KW - uranium remediation
UR - http://www.scopus.com/inward/record.url?scp=85189910080&partnerID=8YFLogxK
U2 - 10.1021/acs.est.3c10324
DO - 10.1021/acs.est.3c10324
M3 - Article
C2 - 38573735
AN - SCOPUS:85189910080
VL - 58
SP - 6595
EP - 6604
JO - Environmental Science and Technology
JF - Environmental Science and Technology
SN - 0013-936X
IS - 15
ER -