U(VI) reduction during in situ bioremediation is often thought to primarily occur via enzymatic reactions driven by indigenous DMRB, which is the intent of biostimulation of uranium-contaminated sites. This study contributes to a growing body of evidence for abiotic processes mediated by biogenic minerals leading to the reductive immobilization of uranium. Abiotic uranium reduction mediated by biogenic minerals such as mackinawite leading to the formation of UO2 is one of the other important processes to consider when devising bioremediation schemes.

H. Veeramani, A.C. Scheinost, N. Monsegue, N.P. Qafoku, R. Kukkadapu, M. Newville, A. Lanzittori, A. Pruden, M. Murayama, M.F. Hochella, “Abiotic Reductive Immobilization of U(VI) by Biogenic Mackinawite”, Environ. Sci. Technol, 2013, 47(5), pp. 2361-2369

(A) SEM image
(B and C) TEM brightfield image
(D) SAED pattern taken from an area biogenic mackinawite that is shown in 1C
(E) HRTEM image of biogenic mackinawite. HRTEM shows Moiréfringes at a fold and a set of (101) lattice fringes confirmed by (F) fast Fouriertransform from the region.

(A) Magnified SEM image showing UO2nanoparticles (indicated by arrows) on the surface of biogenic mackinawite
(B) UO2nanoparticles on the surface of biogenic mackinawite observed by HRTEM
(C) a corresponding nanodiffraction pattern confirming the presence ofcrystalline UO2phase.