Journal
JOURNAL OF RADIOANALYTICAL AND NUCLEAR CHEMISTRY
Volume 298, Issue 1, Pages 25-32Publisher
SPRINGER
DOI: 10.1007/s10967-013-2491-1
Keywords
Natural radioactivity; Sediment; Var river; Cs-137; Sequential extraction; Radionuclide speciation
Funding
- Atomic Energy Commission of Syria (AECS)
- Conseil General des Alpes Maritimes
- Agence de l'Eau RMC
- Conseil Regional PACA
- Syndicat Mixte d'Etudes de la Basse Vallee du Var
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This paper reports results on the natural and anthropogenic radionuclides activity concentrations in sediments of the Var river and its tributaries. Natural (U-238, Th-232 and K-40) and artificial (Cs-137) radionuclides activities were measured using high purity germanium detector. Measured activity concentrations differ widely; they depend on the pertinent environmental situation such as the presence of dams, and sediments type. Other factors controlling the distribution of the studied radioisotopes have been discussed. A sequential extraction method consisting of six operationally-defined fractions has been used for determining the geochemical partitioning of anthropogenic radionuclide Cs-137 in a 405-410 cm deep sediments collected in the lower valley of the Var river. This method corresponds to a modification of the three-stage sequential extraction procedure proposed by the Commission of the European Communities Bureau of Reference (BCR, now Standards, Measurements and Testing Program). Two steps with weak reagents, (fraction A: water; fraction B: nitric acid 0.001 M), were added before the first step of BCR (carbonate fraction) in order to better detect anthropogenic components. A total acid digestion of solid residues by microwave assisted was also added. The 6-steps extraction method was tested and validated by certified reference materials. Cs-137 was found mostly in the hydrosoluble fraction (20-24 %), oxide and hydroxide fraction (22-25 %) and in the residue (51-58 %), while Cs-133 was mostly found in the residual fraction (> 97 %).
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