Quick
Search: 		  
advanced search
 GSW Home   GeoRef Home   My GSW Alerts   Contact GSW   About GSW   Journals List   Help 
Clays and Clay Minerals Signup for GSW Email News
JOURNAL HOME HELP CONTACT PUBLISHER SUBSCRIBE ARCHIVE SEARCH TABLE OF CONTENTS
Clays and Clay Minerals; December 2007; v. 55; no. 6; p. 635-643; DOI: 10.1346/CCMN.2007.0550610
© 2007 Clay Minerals Society
This Article
Right arrow Figures Only
Right arrow Full Text
Right arrow Full Text (PDF)
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Similar articles in ISI Web of Science
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrow reprints & permissions
Citing Articles
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Grathoff, G. H.
Right arrow Articles by Hugo, R. C.
Right arrow Search for Related Content
GeoRef
Right arrow GeoRef Citation

MIXED-VALENT Fe FILMS (‘SCHWIMMEISEN’) ON THE SURFACE OF REDUCED EPHEMERAL POOLS

Georg H. Grathoff1, John E. Baham2, Heather R. Easterly1, Paul Gassman3 and Richard C. Hugo1

1 Department of Geology, Portland State University, Portland, OR 97207-0751, USA
2 Department of Crop and Soil Science, Oregon State University, Corvallis, OR 97331-7306, USA
3 Pacific Northwest National Laboratory (PNNL), Richland, WA 99352, USA

* E-mail address of corresponding author: GrathoffG{at}pdx.edu

Floating, mixed-valent Fe films have been observed worldwide in wetlands, ferrous iron-rich seeps, and in seasonally reduced soils, but are usually misidentified as oil or biofilms. There has been little characterization or explanation of their formation. Along the Oregon coast such films were found on ephemeral pools where Fe(II)-rich groundwater (~100 µM Fe) has been discharged at the base of Pleistocene sand dunes. Fe(II) oxidized to Fe(III) at the air-water interface to form ~100–300 nm thick films. Analyses indicated that the films contained both Fe(III) and Fe(II) in a ratio of 3:1; Si was the other main cation; OH was the main anion and some C was also identified. The film morphology was flat under optical and electron microscopy with some attached floccules having a string-like morphology. Energy-filtered electron diffraction patterns showed three diffraction rings at 4.5, 2.6 and 1.4 Å in some places and two rings (2.6 and 1.4 Å) in others. Upon further oxidation the films became 2-line ferrihydrite. We are proposing the name ‘schwimmeisen’ for the floating, mixed-valent Fe film.

Key Words: • Ephemeral Pools • Ferrihydrite • Floating Fe Film • Geochemistry • Mineralogy • Morphology • Mixed-valent • Soils






JOURNAL HOME HELP CONTACT PUBLISHER SUBSCRIBE ARCHIVE SEARCH TABLE OF CONTENTS
Copyright © 2008 by Clay Minerals Society