Fig. 7. Distribution of Fe in aquifer solids after 21 d of incubation with glucose at 200, 2000, and 20 000 mg C L^–1 and acetate at 2000 mg C L^–1 compared with aquifer solids before incubation. Columns with the same letter within extraction type are not significantly different by the Bonferroni–Dunn procedure. There was no measurable Fe(II) in the solution phase or extracted with HCl for the original aquifer solids before treatment.