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GEOREF RECORD

Characterization of microbially Fe(III)-reduced nontronite; environmental cell-transmission electron microscopy study

Jin-wook Kim, Yoko Furukawa, Tyrone L. Daulton, Dawn Lavoie and Steven W. Newell
Characterization of microbially Fe(III)-reduced nontronite; environmental cell-transmission electron microscopy study
Clays and Clay Minerals (August 2003) 51 (4): 382-389

Abstract

Microstructural changes induced by the microbial reduction of Fe(III) in nontronite by Shewanella oneidensis were studied using environmental cell (EC)-transmission electron microscopy (TEM), conventional TEM, and X-ray powder diffraction (XRD). Direct observations of clays by EC-TEM in their hydrated state allowed for the first time an accurate and unambiguous TEM measurement of basal layer spacing and the contraction of layer spacing caused by microbial effects, most likely those of Fe(III) reduction. Non-reduced and Fe(III)-reduced nontronite, observed by EC-TEM, exhibited fringes with mean d (sub 001) spacing of 1.50 nm (standard deviation, sigma = 0.08 nm) and 1.26 nm (sigma = 0.10 nm), respectively. In comparison, the same samples embedded with Nanoplast resin, sectioned by microtome, and observed using conventional TEM, displayed layer spacings of 1.0-1.1 nm (non-reduced) and 1.0 nm (reduced). The results from Nanoplast-embedded samples are typical of conventional TEM studies, which have measured nearly identical layer spacings regardless of Fe oxidation state. Following Fe(III) reduction, both EC-and conventional TEM showed an increase in the order of nontronite selected area electron diffraction patterns while the images exhibited fewer wavy fringes and fewer layer terminations. An increase in stacking order in reduced nontronite was also suggested by XRD measurements. In particular, the ratio of the valley to peak intensity (v/p) of the 1.7 nm basal 001 peak of ethylene glycolated nontronite was measured at 0.65 (non-reduced) and 0.85 (microbially reduced).


ISSN: 0009-8604
EISSN: 1552-8367
Coden: CLCMAB
Serial Title: Clays and Clay Minerals
Serial Volume: 51
Serial Issue: 4
Title: Characterization of microbially Fe(III)-reduced nontronite; environmental cell-transmission electron microscopy study
Affiliation: Naval Research Laboratory, Marine Geosciences Division, Stennis Space Center, MS, United States
Pages: 382-389
Published: 200308
Text Language: English
Publisher: Clay Minerals Society, Clarkson, NY, United States
References: 34
Accession Number: 2003-082779
Categories: Geochemistry of rocks, soils, and sediments
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus.
Secondary Affiliation: U. S. Geological Survey, USA, United States
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute.
Update Code: 200324
Program Name: USGSOPNon-USGS publications with USGS authors
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