Distribution coefficient Kd of transuranics in soils : Experimental determination and consequences for dose assessment

Abstract

Abstract. Tfae distribution coefficient (or Kd) of 341 Am between soil and soil solution was estimated on the basis of experiments carried out under controlled conditions for soils displaying pH and organic matter content (which are the relevant parameters for transuranic nuclides sorption ability) found in cultivated soils. In these experiments, designed with five experimental units (batches) per studied contact time, 10 g of dry soil are contaminated with 50 mL of osmosed water containing proper concentrations of the radionuclide. The tracer, initially in nitric form, is neutralized prior to addition with the water, to ensure a constant ionic strength and avoid disturbance of the soil chemistry. After shaking and sedimentation, for each batch, the supernatant is sampled and analyzed by either liquid scintillation or alpha spectrometry. The sorption-desorption kinetic time necessary to reach apparent equilibrium is evaluated (>10 days). Fixation curves, e.g. activity of the soil vs activity of the solution are established, after measurements, for a single delay representative of the equilibrium, and for a range of several orders of magnitude for radionuclide concentrations. On the basis of several assumptions, Kd values are evaluated by simple linear adjustment. A numerical application to retention half lives in soil is made. Finally, the weight of using site-specific Kd values instead of default parameters, on the doses due to ingestion of terrestrial foodstuffs is discussed for different scenarios.

Specificity and Origin of the Stability of the Sr Isotopic Ratio in Champagne Wines

“…Several studies have addressed this question and did not reveal any differences in the Sr isotopic signatures during the different stages of wine production. [ 3 , 12 , 13 , 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 ]. However, in very few specific cases, mostly dealing with white wine productions, the use of filtration and adjuvants or the removal of specific parts of the grape (skin, pips and stalks) have been reported to slightly alter the final Sr isotopic composition of the product [ 16 ].…”

“…Hence, the biochemical Sr signature can be compared for musts from various origins and Champagne by plotting the Sr isotopic ratio as a function of the concentration of Sr (1/[Sr]) as presented in Figure 6 . Despite the large variation of Sr in the soils (10 to 1000 mg/kg) [ 23 ], the overall isotopic Sr signatures in the musts do only vary in a very small range between 0.70780 and 0.70830.…”

β-Radiation Stress Responses on Growth and Antioxidative Defense System in Plants: A Study with Strontium-90 in Lemna minor

“…Among the artificially produced radionuclides, strontium-90 ( 90 Sr) is of particular interest due to its relative long physical half-live of 28.6 years. It is produced with high yields as a byproduct of the fission of uranium and plutonium and is thus a common waste product from nuclear activities [ 2 ]. Also, the explosions of nuclear weapons in the 1950s and 1960s contributed to the widespread distribution of 90 Sr in the environment [ 3 ].…”