Microbial mass-dependent fractionation of chromium isotopes
Geochimica et Cosmochimica Acta
By: E.R. Sikora, T. M. Johnson, and T.D. Bullen
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Abstract
Mass-dependent fractionation of Cr isotopes occurs during dissimilatory Cr(VI) reduction by Shewanella oneidensis strain MR-1. Cells suspended in a simple buffer solution, with various concentrations of lactate or formate added as electron donor, reduced 5 or 10 ??M Cr(VI) to Cr(III) over days to weeks. In all nine batch experiments, 53Cr/52Cr ratios of the unreacted Cr(VI) increased as reduction proceeded. In eight experiments covering a range of added donor concentrations up to 100 ??M, isotopic fractionation factors were nearly invariant, ranging from 1.0040 to 1.0045, with a mean value somewhat larger than that previously reported for abiotic Cr(VI) reduction (1.0034). One experiment containing much greater donor concentration (10 mM lactate) reduced Cr(VI) much faster and exhibited a lesser fractionation factor (1.0018). These results indicate that 53Cr/52Cr measurements should be effective as indicators of Cr(VI) reduction, either bacterial or abiotic. However, variability in the fractionation factor is poorly constrained and should be studied for a variety of microbial and abiotic reduction pathways. ?? 2008 Elsevier Ltd.
| Publication type | Article |
|---|---|
| Publication Subtype | Journal Article |
| Title | Microbial mass-dependent fractionation of chromium isotopes |
| Series title | Geochimica et Cosmochimica Acta |
| DOI | 10.1016/j.gca.2008.05.051 |
| Volume | 72 |
| Issue | 15 |
| Year Published | 2008 |
| Language | English |
| Larger Work Type | Article |
| Larger Work Subtype | Journal Article |
| Larger Work Title | Geochimica et Cosmochimica Acta |
| First page | 3631 |
| Last page | 3641 |
| Google Analytic Metrics | Metrics page |