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
Abstract
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.
