EFFECT OF ALUMINUM SUBSTITUTION ON FERRI-REDUCING BACTERIAL-ACTIVITY AND DISSOLUTION OF GOETHITES

Goethites samples substituted (5 % and 33 %) by aluminium were synthes ized and characterized by X-ray diffraction. Their bacterial reductive dissolution was investigated and compared to that obtained with non-s ubstituted goethite. Bacterial fermentation and reduction processes ar e not significantly modified by the presence of Al; however, the disso lution rates of iron decreased with increasing Al substitution and Al released incongruently with Fe. The nature and the concentration of su bstituted metals are of fundamental interest in these microbial weathe ring processes. (C) Academie des sciences/Elsevier, Paris.