@article{743413ea7b27487d9d9d780af927978b,
title = "Microbial U Isotope Fractionation Depends on the U(VI) Reduction Rate",
abstract = "U isotope fractionation may serve as an accurate proxy for U(VI) reduction in both modern and ancient environments, if the systematic controls on the magnitude of fractionation (ϵ) are known. We model the effect of U(VI) reduction kinetics on U isotopic fractionation during U(VI) reduction by a novel Shewanella isolate, Shewanella sp. (NR), in batch incubations. The measured ϵ values range from 0.96 ± 0.16 to 0.36 ± 0.07‰ and are strongly dependent on the U(VI) reduction rate. The ϵ decreases with increasing reduction rate constants normalized by cell density and initial U(VI). Reactive transport simulations suggest that the rate dependence of ϵ is due to a two-step process, where diffusive transport of U(VI) from the bulk solution across a boundary layer is followed by enzymatic reduction. Our results imply that the spatial decoupling of bulk U(VI) solution and enzymatic reduction should be taken into account for interpreting U isotope data from the environment.",
author = "Anirban Basu and Christoph Wanner and Johnson, {Thomas M.} and Lundstrom, {Craig C.} and Sanford, {Robert A.} and Sonnenthal, {Eric L.} and Boyanov, {Maxim I.} and Kemner, {Kenneth M.}",
note = "Funding Information: This work was supported by the U.S. Department of Energy (USDOE), Office of Science within the Subsurface Biogeochemical Research (SBR) Program under grant DE-SC0001281. We thank the MRCAT/EnviroCAT beamline staff for assistance during XAFS data collection. The XAFS data collection at the Advanced Photon Source and analyses and effort of K.M.K. and M.I.B. were supported by the Argonne Wetlands Hydrobiogeochemistry Scientific Focus Area (SFA) at the Argonne National Laboratory funded by the SBR Program, Office of Biological and Environmental Research, Office of Science, USDOE, under contract DE-AC02-06CH11357. MRCAT/EnviroCAT operations are supported by DOE and the MRCAT/EnviroCAT member institutions. We thank the anonymous reviewers for their insightful comments. Funding Information: This work was supported by the U.S. Department of Energy (USDOE), Office of Science within the Subsurface Biogeochemical Research (SBR) Program under grant DE-SC0001281. We thank the MRCAT/EnviroCAT beamline staff for assistance during XAFS data collection. The XAFS data collection at the Advanced Photon Source and analyses and effort of K.M.K. and M.I.B. were supported by the Argonne Wetlands Hydrobiogeochemistry Scientific Focus Area (SFA) at the Argonne National Laboratory funded by the SBR Program, Office of Biological and Environmental Research Office of Science, USDOE, under contract DE-AC02-06CH11357. MRCAT/EnviroCAT operations are supported by DOE and the MRCAT/EnviroCAT member institutions. We thank the anonymous reviewers for their insightful comments. Publisher Copyright: {\textcopyright} 2020 American Chemical Society.",
year = "2020",
month = feb,
day = "18",
doi = "10.1021/acs.est.9b05935",
language = "English (US)",
volume = "54",
pages = "2295--2303",
journal = "Environmental Science and Technology",
issn = "0013-936X",
publisher = "American Chemical Society",
number = "4",
}