Organic carbon is often associated with iron (Fe) minerals in soils and sediments and has become of increasing interest because of the potential for carbon storage to mediate climate change. Ferrihydrite, an Fe mineral commonly associated with carbon, is known to transform in the presence of Fe(II) raising the question of the long-term stability of carbon in ferrihydrite. Here we explore the effect of different organic carbon types on Fe(II)-catalyzed ferrihydrite transformation. Specifically, we measured Fe atom exchange and ferrihydrite transformation for ferrihydrite-carbon aggregates reacted with aqueous Fe(II). In addition, we characterized Fe(II)-Fe(III) electron transfer on ferrihydrite in the presence of organic carbon. Interestingly, we found that ferrihydrite co-precipitated with Suwanee River Fulvic Acid (SRFA) did not transform to other minerals, but Fe atom exchange still occurred. Additional work is being done to determine if the organic carbon redistributes during the exchange of Fe atoms and whether exchange alters carbon availability.

Ferrihydrite – Carbon dynamics in the presence of Fe(II)

253rd National Meeting (2017)

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