Influence of Solid Phase Fe(II) on Fe(III) Bioavailability in Aquifer Sediment

Abstract

The availability of Fe(III) for microbial reduction was measured in macrocosms containing contaminated aquifer sediment with benzaldehyde as the organic substrate. Repeated benzaldehyde additions initially resulted in an increase in Fe(II) and decrease in Fe(III). However, after ∼400 h total Fe(II) and Fe(III) stabilized and both ethanol and benzylalcohol began to accumulate, indicating a shift in microbial processes from iron reduction to fermentation. Addition of Fe(III) as amorphous–oxyhydroxide, goethite, and hematite to the Fe(III) depleted sediment stimulated ethanol and benzylalcohol degradation. Washing the sediment with