Comparison of Methods for Assessment of Radionuclide Speciation in Soils

• Published in: Biology bulletin of the Russian Academy of Sciences 2019-12, Vol.46 (12), p.1671-1678
• Main Authors: Manakhov, D. V., Emelyanov, A. M., Karpukhin, M. M., Lipatov, D. N., Agapkina, G. I., Mamikhin, S. V.
• Format: Article
• Language: English
• Subjects: Biochemistry; Biomedical and Life Sciences; Cell Biology; Ecology; Life Sciences; Radioisotopes; Radionuclides; Soil chemistry; Speciation; Strontium; Zoology
• ISSN: 1062-3590; 1608-3059
• DOI: 10.1134/S1062359019120057

A comparison of sequential extraction methods proposed by F.I. Pavlotskaya [1, 2] and A. Tessier [3] for fractionation of technogenic ( 137 Cs and 90 Sr) and natural ( 226 Ra, 232 Th, and 238 U) radionuclides from soils was performed. It is shown that both methods provide comparable results in the extraction of various forms of occurrence of technogenic radionuclides. Furthermore, both methods indicate a significantly higher availability of 90 Sr to plants and its greater ability to migrate with downward soil solution flows in comparison with 137 Cs. However, when used for the assessment of the occurrence forms of natural heavy radionuclides, the two methods provide inconsistent results. The Tessier sequential extraction method indicates higher contents of compounds available to plants and mobile compounds in comparison with the Pavlotskaya method. A possible reason behind this may be the soil chemistry complexity of radionuclides such as 232 Th and 238 U that feature polyvalence and a strong tendency for hydrolysis and complex formation; in addition, their behavior may be affected by various carriers. These elements form a broad range of compounds that change one into another with changes in the chemical conditions; this complicates accurate comparison of the composition of their forms extracted by reagents used in the above methods.