Fe geochemistry (contact: Rasmus Jakobsen)
Iron oxides may oxidize both natural organic matter and organic pollutants. Because of their abundance, iron oxides form one of the most important electron acceptors in aquatic systems and control the release and retention of e.g. phosphate and arsenic. In sediments, iron oxides are present as a suite of different minerals with major differences in reactivity. The reduction of iron oxides in sediments is often mediated by bacteria. The Fe2+ produced may catalyze the abiotic transformation of the most reactive Fe-oxides to more stable Fe-oxides as we have shown in lab experiments, it is, however, still uncertain to what extent this occurs in natural systems. This and the peculiarity that Fe-oxides are solid electron acceptors posing specific challenges for the microorganisms are part of current investigations. Fe-oxides are also very important as sorbents in natural aquifer systems, we currently investigate the feasibility of using Fe-oxides for lowering leaching of chromium and arsenic from polluted soils.