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| Titel |
Cr isotope fractionation in metal-mineral-microbe interactions |
| VerfasserIn |
Qiong Zhang, Don Porcelli, Ian Thompson, Ken Amor, Stephen Galer |
| Konferenz |
EGU General Assembly 2016
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| Medientyp |
Artikel
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| Sprache |
en
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 18 (2016) |
| Datensatznummer |
250136496
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| Publikation (Nr.) |
 EGU/EGU2016-17545.pdf |
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| Zusammenfassung |
| Microbes interact with metals and minerals in the environments, altering their physical and
chemical state whilst in turn the metals and minerals affect microbial growth, activity and
survival. The interactions between Cr, Fe minerals and bacteria were investigated in this
study. Cr(VI) reduction experiments by two iron-reducing bacteria, Pseudomonas fluorescens
LB 300 and Shewanella oneidensis MR 1, in the presence of two iron oxide minerals,
goethite and hematite, were conducted. Both minerals were found to inhibit the Cr(VI)
reduction rate by Pseudomonas fluorescens LB 300 but accelerated Shewanella
oneidensis MR 1. The Cr isotopic fractionation factor generated by both bacteria
was mostly independent of the presence of the minerals, except for hematite with
Pseudomonas fluorescens LB 300, where the ɛ was much higher. Aqueous Fe(III) in the
solution did not have any detectable impact on either bacterial Cr reduction rates or
the isotopic fractionation factors, indicating that the reduction of Cr(VI) occurred
prior to that of Fe(III). The presence of aqueous Fe(II) induced a very fast abiotic
reduction of Cr, but had little impact on the bacterial Cr reduction rates or its isotope
fractionations. The evidence suggests that the different impact that Fe minerals
had on the bacteria were related to the way they attached to the minerals and the
difference in the reduction mechanism. SEM images confirmed that the attachment of
Pseudomonas fluorescens LB 300 on the mineral surfaces were much more tightly packed
than that of Shewanella oneidensis MR 1, so reducing mineral-metal interactions. |
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