Effect of sample drying and storage time on the extraction of fallout Pu239+240, Cs-137 and natural Pb-210 as well as of stable Cs, Pb and Mn from soils

Because substantial evidence exists that sample drying and storage may have an effect on the extractability of trace metals from soils and sediments, we have examined whether such effects are also present for the typical fall out radionuclides Cs-137 and Pu239+240, for natural Pb-210, as well as for the corresponding stable elements Cs and Pb. For comparison, stable Mn was also included, because for this element a clear effect of drying and storag e has been demonstrated recently. The sequential extraction procedure of Te ssier was applied to two soils (a typical mineral soil with a low organic m atter content, and the top layer of a forest soil with a high organic matte r content). No substantial effect of air-drying and subsequent sample stora ge up to 30 weeks was detectable for Cs-137, Pu239+240 and Pb-210 as well a s for stable Cs and Pb. A clear effect of drying and subsequent sample stor age was observable for stable Mn extracted from the mineral soil into fract ion I, where its concentration increased continually with storage time. Thi s supports an earlier observation reported in the literature for a similar soil. Nevertheless, because we did not observe such an effect for the soil with the high organic matter content, one should be careful about generaliz ing this result. The results also suggest that isotopic equilibrium between Cs-137 and stable Cs as well as between Pb-210 and stable Pb in the two so ils is approximately established.