| 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. |
| Genre: | Article |
| ProdID: | 70000285 |
| Citation Author: | Sikora, E. R.; Johnson, T. M.; Bullen, T. D. |
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| Citation End Page: | 3641 |
| Citation Issue: | 15 |
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| Citation Language: | English |
| Citation Larger Work Title: | Geochimica et Cosmochimica Acta |
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| Citation Search Results Text: | Microbial mass-dependent fractionation of chromium isotopes; 2008; Article; Journal; Geochimica et Cosmochimica Acta; Sikora, E. R.; Johnson, T. M.; Bullen, T. D. |
| Citation Start Page: | 3631 |
| Citation Volume: | 72 |
| Citation Year: | 2008 |
| Type: | citation/reference |
| Text: | Microbial mass-dependent fractionation of chromium isotopes; 2008; Article; Journal; Geochimica et Cosmochimica Acta; Sikora, E. R.; Johnson, T. M.; Bullen, T. D. |
| URL (THUMBNAIL): | http://pubs.er.usgs.gov/thumbnails/outside_thumb.jpg |
| URL (DIGITAL OBJECT IDENTIFIER): | http://dx.doi.org/10.1016/j.gca.2008.05.051 |
| Date Other: | Tue, 28 Sep 2010 23:09 -0500 |
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