XAFS and x-ray and electron microscopy investigations of radionuclide transformations at the mineral-microbe interface.
The microenvironment at and adjacent to surfaces of actively metabolizing cells, whether in a planktonic state or adhered to mineral surfaces, can be significantly different from the bulk environment. Microbial polymers (polysaccharides, DNA, RNA, and proteins), whether attached to or released from the cell, can contribute to the development of steep chemical gradients over very short distances. It is currently difficult to predict the behavior of contaminant radionuclides and metals in such microenvironments, because the chemistry there has been difficult or impossible to define. The behavior of contaminants in such microenvironments can ultimately affect their macroscopic fates. We have successfully performed a series of U L{sub III} edge x-ray absorption fine structure (XAFS) spectroscopy, hard x-ray fluorescence (XRF) microprobe (150 nm resolution), and electron microscopy (EM) measurements on lepidocrocite thin films ({approx}1 micron thickness) deposited on kapton films that have been inoculated with the dissimilatory metal reducing bacterium Shewanella oneidensis MR-1 and exposed to 0.05 mM uranyl acetate under anoxic conditions. Similarly, we have performed a series of U L{sub III} edge EXAFS measurements on lepidocrocite powders exposed to 0.05 mM uranyl acetate and exopolymeric components harvested from S. oneidensis MR-1 grown under aerobic conditions. These results demonstrate the utility of combining bulk XAFS with x-ray and electron microscopies.
- Research Organization:
- Argonne National Lab. (ANL), Argonne, IL (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC)
- DOE Contract Number:
- DE-AC02-06CH11357
- OSTI ID:
- 973749
- Report Number(s):
- ANL/BIO/CP-119067; TRN: US201006%%1100
- Resource Relation:
- Conference: 13th International Conference on X-ray Absorption Fine Structure (XAFS13); Jul. 9, 2006 - Jul. 14, 2006; Stanford, CA
- Country of Publication:
- United States
- Language:
- ENGLISH
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Related Subjects
99 GENERAL AND MISCELLANEOUS//MATHEMATICS, COMPUTING, AND INFORMATION SCIENCE
ABSORPTION
ACETATES
AEROBIC CONDITIONS
CHEMISTRY
DNA
ELECTRON MICROSCOPY
ELECTRONS
FINE STRUCTURE
FLUORESCENCE
POLYMERS
POLYSACCHARIDES
PROTEINS
RADIOISOTOPES
RESOLUTION
RNA
SPECTROSCOPY
THICKNESS
THIN FILMS
TRANSFORMATIONS