SREL Reprint #2126





A Comparison of Sequential Extraction Techniques to Estimate Geochemical Controls on the Mobility of Fission Product, Actinide, and Heavy Metal Contaminants in Soils

S. B. Clark1, W. H. Johnson 2,3, M. A. Malek1, S. M. Serkiz3 and T. G. Hinton1

1University of Georgia, Savannah River Ecology Laboratory, P. 0. Drawer E, Aiken, SC 29802, USA
2Nuclear Engineering and Health Physics Programs, School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, GA 30332, USA
3Westinghouse Savannah River Company, Building 773-43A, Aiken, SC 29802, USA


Two sequential extraction methods have been used to estimate the geochemical availability of uranium, lead, and cesium contaminants in soils. Soils were well-characterized, and the distributions of naturally-occurring elements as well as contaminants were determined in each operationally-defined extract. This approach provided experimental evidence required to understand which of the soil phases dissolved in each step. Since U and Pb can also occur in soils naturally, knowledge of the dissolution of insoluble soil phases and the fractions of U and Pb associated with these phases allows an estimation of the amount of contaminant that is unavailable for transport in the aqueous phase under normal geochemical conditions. This approach provided a more representative estimate of "background" or residual concentrations of contaminants than determination of total contaminant concentrations in soils collected from uncontaminated areas. Comparisons between the two sequential techniques were also possible, with both methods indicating consistent trends. A simplified five-step method tended to provide lower estimates of metals bound within the refractory soil matrix.

SREL Reprint #2126

Clark, S.B., W.B. Johnson, M.A. Malek, S.M. Serkiz, and T.G. Hinton. 1996. A comparison of sequential extraction techniques to estimate geochemical controls on the mobility of fission product, actinide, and heavy metal contaminants in soils. Radiochimica Acta 74:173-179.

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