 |
| Titel |
Biological effect of Acidithiobacillus thiooxidans on some potentially toxic elements during alteration of SON 68 nuclear glass |
| VerfasserIn |
M. Bachelet, J. L. Crovisier, P. Stille, S. Vuilleumier, V. Geoffroy |
| Konferenz |
EGU General Assembly 2009
|
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 11 (2009) |
| Datensatznummer |
250024139
|
|
|
|
|
|
| Zusammenfassung |
| Although underground nuclear waste repositories are not expected to be favourable places for
microbial activity, one should not exclude localized action of extremophilic bacteria on some
materials involved in the storage concept. Among endogenous or accidentally introduced
acidophiles, some are susceptible to lead to a locally drastic decreased in pH, with potential
consequences on materials corrosion. Experiments were performed with Acidithiobacillus
thiooxidans on 100-125 μm french reference nuclear glass SON68 grains in a mineral
medium under static conditions during 60 days at 25degC. Growth medium was periodically
renewed and analyzed by ICP-AES and ICP-MS spectrometry for both major, trace and
ultra-trace elements. Biofilm formation was evidenced by confocal laser microscopy, staining
DNA with ethidium bromide and exopolysaccharides with calcofluor white. Biofilm
thickness around material grains exceeded 20 μm under the chosen experimental
conditions. It can be noticed that while numerous studies on biofilm formation
upon interaction between Acidithiobacillus ferrooxidans and materials are found
in the literature, evidence for biofilm formation is still scarce for the case of the
acidophilic bacterium A. thiooxidans. Presence of biofilm is a key parameter for
material alteration at the solid/solution interface in biotic systems. Indeed, various
constitutive elements of materials trapped in the polyanionic polymer of biofilm
may also influence the alteration process. In particular, biofilm may reduce the
alteration rate of materials by forming a protective barrier at their surface (Aouad et al.,
2008). In this study, glass alteration rates, determined using strontium as tracer,
showed that the progressive formation of a biofilm on the surface of glass has a
protective effect against its alteration. Uranium and rare earth elements (REE) are
efficiently trapped in the biogenic compartment of the system (exopolysaccharides +
bacterial cells). Besides, the ratio biotic/abiotic concentrations of REE and U in the
leachant decreases with increasing time which seems to indicate a good capacity
of EPS for long term trapping of potentially toxic elements. Aouad G., Crovisier
J.-L., Damidot D., Stille P., Hutchens E., Mutterer J., Meyer J.-M., and Geoffroy V.
A. (2008) Interactions between municipal solid waste incinerator bottom ash and
bacteria (Pseudomonas aeruginosa). Science of The Total Environment 393((2-3)),
385-393. |
|
|
|
|
|
|