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