Journal Article
Proceedings of the National Academy of Sciences, vol. 116, iss. 8, pp. 2866-2874, 2019
Authors
Sandra D. Taylor, Jia Liu, Xin Zhang, Bruce W. Arey, Libor Kovarik, Daniel K. Schreiber, Daniel E. Perea, Kevin M. Rosso
Abstract
Significance
The bioavailability of iron in the environment, and coupled metals, nutrients, and contaminants, depends on the stability of common Fe(III) minerals such as goethite (FeOOH) and hematite (Fe
2
O
3
). At redox boundaries, iron isotopic tracer studies suggest that interaction with aqueous Fe(II) creates dynamic conditions of atom exchange (AE). However, mechanistic models have not advanced beyond speculation, because of the challenges of mapping AE fronts recorded in isotopic distributions in individual nanoscale crystallites. Here we demonstrate successful use of 3D atom probe tomography for this purpose. The penetration depth, spatial heterogeneity, and ties to mineral defects are visualized, helping constrain mechanistic models and setting a precedent for detailed interrogation of iron redox cycling in the environment.
