Abstract
The influence of bacteria and vegetation on glass alteration and trace metal mobility has rarely been considered in-depth by geochemists and, therefore, the exact role of microorganisms in these alteration processes remains unclear and has still to be clarified by convincing experiments. We compared the stability of natural basaltic and artificial waste glasses in solutions with and without bacteria. 40 to 50% more REE have been leached out of waste glasses under bacteria-free sterile conditions than under biotic conditions. This suggests that bacteria slow down alteration processes due to the development of a protecting biofilm at the surface of the glass grains
