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Evaluation of 55Fe as a tracer of Fe(III) reduction in aquatic sediments

E. E. Roden·Derek R. Lovley
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Abstract

The potential utility of 55 Fe as a tracer for Fe(III) reduction in aquatic sediments was evaluated using freshwater sediments from the Potomac River, Md, in which Fe(III) reduction was the predominant terminal electron accepting process. In laboratory incubations of sediments amended with poorly crystalline 55 Fe(III) oxide, the accumulation of 55 Fe in Fe(II) over time paralleled Fe(II) production. However, within 1 h of addition of 55 Fe(III) oxide, significant quantities of 55 Fe were recovered in extractable (1 M sodium acetate, pH 5) and soluble Fe(II) pools. There was proportionately more 55 Fe(II) activity in sediments with higher Fe(II) concentrations. These results suggest that there was rapid isotopic exchange between 55 Fe in poorly crystalline Fe(III) oxide and the Fe(II) pools. Because of this exchange, 55 Fe could not be used to trace Fe(III) reduction in sediments in the manner that 35 SO 4 2− is used to trace sulfate reduction. Although accumulation of 55 Fe in Fe(II) pools paralleled unla‐beled Fe(II) production, given the relative ease with which Fe(II) pools in sediments can be measured there is no apparent advantage to using 55 Fe to follow Fe(III) reduction.

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BibTeXRIS

E. E. Roden, Derek R. Lovley. 1993. Evaluation of 55Fe as a tracer of Fe(III) reduction in aquatic sediments. https://doi.org/10.1080/01490459309377931

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