Micro-Mineralogical Analysis of Strontium in Biogenic Carbonate Minerals
EMSL Project ID
2007
Abstract
In recent EMSP-funded research (96-10 program), we have documented the potential for solid-phase capture of strontium (Sr) during carbonate mineral formation coupled to bacterial reduction of amorphous hydrous ferric oxide (HFO). Wet-chemical analysis of HFO reduction end-products suggest that Sr is incorporated into siderite (FeCO3) minerals formed during bacterial Fe(III) oxide reduction. In addition, SEM-EDX analysis of solid-phase HFO reduction end-products indicates that Sr is associated with FeCO3 phases. However, with the technology thus far available to our research program we have been unable to determine the exact nature of the Sr-bearing solid-phase(s) produced during HFO reduction. This is an important consideration for understanding the potential role which bacterial Fe(III) oxide reduction could play in the fate and transport of Sr in subsurface environments. In the proposed EMSL collaboration with Dr. Yuri Gorby of PNNL, mineral phases formed during bacterial HFO reduction will be identified using high resolution transmission electron microscopy with lattice fringe imaging. With this technology, we anticipate being able detect Sr-bearing carbonate phases associated with heterogeneous nucleation sites in the solid-phase end-products of HFO reduction, including surfaces of siderite and/or calcite precipitates. It may also be possible to observe distortion of carrier carbonate mineral phases as a result the incorporation of Sr (a relatively large ion compared to Fe(II)) into the crystal lattice structure. We will also attempt to identify the presence of Sr associated with mineral surfaces using the newly acquired GIF electron energy loss filter (Gatan Instruments) for element-specific imaging at TEM resolution (1 nm). This system will be used to map the spatial distribution of Sr in relation to Fe, Ca, and C associated with carbonate minerals formed during bacterial HFO reduction.
Project Details
Project type
Exploratory Research
Start Date
2000-08-01
End Date
2003-01-29
Status
Closed
Released Data Link
Team
Principal Investigator
Related Publications
Roden EE, MR Leonardo, and FG Ferris. 2002. "Immobilization of strontium during iron biomineralization coupled to dissimilatory hydrous ferric oxide reduction." Geochimica et Cosmochimica Acta 66(16):2823-2839.