Biogeochemical and mineralogical transformation of biogenic iron-rich minerals under environmental conditions

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Biogenic minerals are minerals that form in close association with microorganisms. In natural environments, iron-rich minerals are often associated with bacteria using the oxidation of iron as a source of energy, which leads to the precipitation of very small iron oxide particles. Given their small size and their inherent large surface area, biogenic iron oxides can sequester large quantities of soluble contaminants, which makes them efficient sorbents in natural remediation strategies where soluble metals are the main contaminants. However, the long term transformation of these minerals is poorly constrained. Do they remain amorphous? Do they transform into more crystalline oxides and re-lease their sorbed contaminants? Do they undergo reduction in anoxic environments? The present proposal is designed to answer these questions by investigating the long term biogeochemical and mineral transformation of various biogenic iron minerals under environmentally relevant conditions. Four graduate students (2 M.Sc. and 2 Ph.D.) will tackle the above questions by performing short and long term ageing experiments and using state-of-the-art characterization techniques, such as electron microscopy, micro X-ray diffraction and synchrotron-based analyses. It is expected that the results will provide valuable information for the potential use of biogenic iron minerals in remediation strategies.