SREL Reprint #1846

 

 

 

 

In Situ Chemical Speciation of Uranium In Soils and Sediments by Micro X-ray Absorption Spectroscopy

Paul M. Bertsch and Douglas S. Hunter
Division of Biogeochemistry, University of Georgia, Savannah River Ecology Laboratory, Drawer E,
Aiken, South Carolina 29802


Stephen R. Sutton, Saia Baft, and Mark L. Rivers
Department of Geophysical Sciences, University of Chicago, and Department of Applied Sciences, Brookhaven National
Laboratory, Upton, New York 11973

Introduction

The ability to develop adequate models for predicting the fate of inorganic contaminants in both surface and subsurface environments is highly dependent on accurate knowledge of the partitioning of these constituents between the solid and solution phases and ultimately on the capability to provide molecular-level information on chemical species distributions in both of these phases. Furthermore, the development of environmentally sound yet cost-effective remediation strategies requires an understanding of the chemical speciation of the contaminants within the soil or sediment matrix in which they are contained. Owing to analytical difficulties, traditional methods for determining speciation of metals in soils and sediments have relied heavily on indirect chemical extraction techniques, in which various phases within the matrix are operationally defined and inferences on chemical associations are generated (1-3). This approach is less than satisfying, since it is not clear what specific reactions take place during the chemical extraction of the operationally defined phases nor what artifacts, such as contaminant element redistributions, may be introduced during and/or following the extraction of a given phase (2). Commonly employed in situ speciation methods (e.g., PIXE, EDX, Y.PS) can potentially avoid such limitations, but these methods have often not been sensitive enough to detect contaminant elements of interest, they require modifications of the sample, or the analysis must be conducted under conditions that may alter chemical species distributions, thus introducing other potential artifacts and complicating data interpretation (3).

SREL Reprint #1846

Bertsch, P.M., D.B. Hunter, S.R. Sutton, S. Bajt, and M.L. Rivers. 1994. In situ chemical speciation of uranium in soils and sediments by micro x-ray absorption spectroscopy. Environmental Science and Technology 28:980-984.

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