Fate of neptunium in an anaerobic, methanogenic microcosm

J. E. Banaszak, S. M. Webb, Bruce Rittmann, J. F. Gaillard, D. T. Reed

Research output: Chapter in Book/Report/Conference proceedingConference contribution

5 Scopus citations

Abstract

Neptunium is found predominantly as Np(IV) in reducing environments, but as Np(V) in aerobic environments. Currently, it is not known how the interplay between biotic and abiotic processes affects Np redox speciation in the environment. To evaluate the effect of anaerobic microbial activity on the fate of Np in natural systems, Np(V) was added to a microcosm inoculated with anaerobic sediments from a metal-contaminated freshwater lake. The consortium included metal-reducing, sulfate-reducing, and methanogenic microorganisms, and acetate was supplied as the only exogenous substrate. Addition of more than 10 -5 M Np did not inhibit methane production. Total Np solubility in the active microcosm, as well as in sterilized control samples, decreased by nearly two orders of magnitude. A combination of analytical techniques, including VIS-NIR absorption spectroscopy and XANES, identified Np(IV) as the oxidation state associated with the sediments. The similar results from the active microcosm and the abiotic controls suggest that microbially produced Mn(II/III) and Fe(II) may serve as electron donors for Np reduction.

Original languageEnglish (US)
Title of host publicationMaterials Research Society Symposium - Proceedings
PublisherMaterials Research Society
Pages1141-1149
Number of pages9
Volume556
StatePublished - 1999
Externally publishedYes
EventProceedings of the 1998 MRS Fall Meeting - Symposium 'Scientific Basis for Nuclear Waste Management XXII' - Boston, MA, USA
Duration: Nov 30 1998Dec 4 1998

Other

OtherProceedings of the 1998 MRS Fall Meeting - Symposium 'Scientific Basis for Nuclear Waste Management XXII'
CityBoston, MA, USA
Period11/30/9812/4/98

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials

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