Retention capacity of bio-films formed on the surface of nuclear and basaltic glasses

Available in abstract form only. Full text of publication follows: The role of the bacteria in the various compartments of a repository site was still not extensively studied. It is likely that most known bacteria cannot develop on the surface of radioactive materials but one must consider that 10% only of the bacteria species are known. As an example, a research group has recently discovered an isolated community of bacteria nearly two miles underground that derives all of its energy from the decay of radioactive rocks (LIN et al., 2006). It is generally accepted that alterations of rocks and anthropogenic products are not exclusively driven by the interaction with water or mineral aqueous solutions. Organic compounds as well as microorganisms are important in mineral degradation processes, and secondary mineralization. However, the exact role of bio-films in these processes remains unclear. The study of (AOUAD, 2006) will be presented as an example. Two materials were tested: the reference French nuclear glass SON68 17 LIDC2A2Z1 and a tholeiitic basaltic glass (natural analogue). Experiments were carried out for 19 weeks at 25 deg. C. A specific growth medium were developed which allows both the growth of Pseudomonas bacterium and a precise measurement, using ICP-MS, of trace elements solubilized from both glasses (AOUAD et al., 2005) The thickness of bio-films, analyzed by confocal laser microscopy was 40 μm for both materials. These bio-films are able to efficiently trap most of the glass constituents. They also form a protective barrier at the solid/solution interface. (authors)