March 1, 2013
Journal Article

Abiotic Reductive Immobilization of U(VI) by Biogenic Mackinawite


During subsurface bioremediation of uranium-contaminated sites, indigenous metal and sulfate-reducing bacteria may utilize a variety of electron acceptors, including ferric iron and sulfate that could lead to the formation of various biogenic minerals in-situ. Sulfides, as well as structural and adsorbed Fe(II) associated with biogenic Fe(II)-sulfide phases, can potentially catalyze abiotic U6+ reduction via direct electron transfer processes. In the present work, the propensity of biogenic mackinawite (Fe1+xS, x = 0 to 0.11) to reduce U6+ abiotically was investigated. The biogenic mackinawite produced by Shewanella putrefaciens strain CN32 was characterized by employing a suite of analytical techniques including TEM, SEM, XAS and Mössbauer analyses. Nanoscale and bulk analyses (microscopic and spectroscopic techniques, respectively) of biogenic mackinawite after exposure to U6+ indicate the formation of nanoparticulate UO2. This study suggests the relevance of Fe(II) and sulfide bearing biogenic minerals in mediating abiotic U6+ reduction, an alternative pathway in addition to direct enzymatic U6+ reduction.

Revised: April 6, 2017 | Published: March 1, 2013


Veeramani H., H. Veeramani, A. Scheinost, N. Monsegue, N. Qafoku, R.K. Kukkadapu, and M. Newville, et al. 2013. Abiotic Reductive Immobilization of U(VI) by Biogenic Mackinawite. Environmental Science & Technology 47, no. 5:2361-2369. PNNL-SA-91214. doi:10.1021/es304025x