EVALUATION OF A SEQUENTIAL EXTRACTION METHOD FOR DETERMINING ACTINIDEFRACTIONATION IN SOILS AND SEDIMENTS

A sequential chemical extraction method for the determination of the g eochemical fractionation of Am, Pu, and U was evaluated rigorously on a single marine sediment standard (IAEA-135), Partitioning of actinide s was operationally defined for five reagent fractions and stable elem ent analyses (Al, Ca, Fe, Mn, Ti, etc.) were performed to assist in es tablishing the phase specificity of the extractions. The method produc es, in general, results that agree to within a one standard deviation interval for replicate measurements for each fraction. Actinide readso rption, examined by a double-spiking technique, was found to be signif icant in some cases. Ethylenediamine-tetraacetic acid (EDTA) was exami ned as a hold-back reagent To lessen the effect of readsorption but se riously compromised the phase selectivity of the extractants, In addit ion, the use of NaOCl for the destruction of organic matter was found to dissolve carbonates out of sequence and is not recommended for carb onate-bearing materials. (C) 1998 Published by Elsevier Science Ltd. A ll rights reserved.