Microbial U Isotope Fractionation Depends on the U(VI) Reduction Rate.
Environ Sci Technol
; 54(4): 2295-2303, 2020 02 18.
Article
em En
| MEDLINE
| ID: mdl-31909614
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.
Texto completo:
1
Bases de dados:
MEDLINE
Assunto principal:
Cromo
/
Fracionamento Químico
Idioma:
En
Revista:
Environ Sci Technol
Ano de publicação:
2020
Tipo de documento:
Article
País de afiliação:
Reino Unido