Comparative kinetic desorption of 60Co, 85Sr and 134Cs from a contaminated natural silica sand column: Influence of varying physicochemical conditions and dissolved organic matter

In order to determine the mechanisms of the retention of 60Co, 85Sr and 134Cs in natural silica sand columns, desorption experiments were performed by changes of pH and ionic strength and by injection of natural organic matter (NOM). Injection of KCl (0.1 M) resulted in a high release of 60Co (60-100%) and 85Sr (72-100%) but a smaller release of 134Cs (31-66%). Only limited release of 60Co (66%) and 85Sr (71%) and no release of 134Cs were observed by injection of NOM. The different percentages of desorption were related to the chemical characteristics of the organic colloids previously retained in columns before the desorption step. The results evidenced different sorption processes on energetically heterogeneous surface sites. According to the initial conditions, the binding of the radionuclides to the solid phase resulted from weak and easily reversible sorption processes to strong association probably by inner sphere complexes. The rather weak release of 134Cs by KCl was attributed to the strong retention of 134Cs by clay coatings on the natural silica sand surfaces. © 2005 Elsevier Ltd. All rights reserved

Interactions between two types of nanoparticles (nC(60) and TiO2) and porous media

19th Annual VM Goldschmidt Conference, Davos, SWITZERLAND, JUN 21, 2009International audienceno abstrac

Influence of the colloid type on the transfer of 60Co and 85Sr in silica sand column under varying physicochemical conditions

The influence of two types of colloids (natural organic matter, NOM), a colloid with high affinity for radionuclides (RN(s)), and hydrophilic synthetic latex (SHL), a colloid with low affinity for RN(s) on the transfer of 60Co and 85Sr in a silica sand column was studied under different physicochemical conditions : pH (4.9), ionic strength (10-3 M and 10-2 M), concentration of colloids (100 mg l-1, 10 mg l-1), flow velocity (12.4 cm h-1 and 3.7 cm h-1), water saturation of the column (100% and 70%). In the absence of colloids, the transfer of 60Co and 85Sr was retarded compared to the transfer of the conservative tracer. In the presence of colloids and according to the specific physicochemical conditions, an acceleration or retardation of 60Co and 85Sr transfer was observed compared to their transfer in the absence of colloids. Our results evidenced that any colloids even with low reactivity could significantly modify the RN transfer. However, the extent to which the transfer was influenced differs according to the colloid type; the NOM exhibiting higher impact than SHL. Batch experiments helped in interpreting of the interactions between the colloids, RN(s) and solid phase observed in column. © 2006 Elsevier Ltd. All rights reserved

Comparative behaviour of recently deposited radiostrontium and atmospheric common strontium in soils (Vosges mountains, France).

International audienc

Comparative migration behaviour of Sr-90, Pu239+240 and Am-241 in mineral and organic soils of France

International audienc

Determining Pu-241 in environmental samples: case studies in alpine soils

A procedure was developed for determining Pu-241 activity in environmental samples. This beta emitter isotope of plutonium was measured by ultra low level liquid scintillation, after several separation and purification steps that involved the use of a highly selective extraction chromatographic resin (Eichrom-TEVA). Due to the lack of reference material for Pu-241, the method was nevertheless validated using four IAEA reference sediments with information values for Pu-241. Next, the method was used to determine the Pu-241 activity in alpine soils of Switzerland and France. The Pu-241/Pu-239,Pu-240 and Pu-238/Pu-239,Pu-240 activity ratios confirmed that Pu contamination in the tested alpine soils originated mainly from global fallout from nuclear weapon tests conducted in the fifties and sixties. Estimation of the date of the contamination, using the Pu-241/Am-241 age-dating method, further confirmed this origin. However, the Pu-241/Am-241 dating method was limited to samples where Pu-Am fractionation was insignificant. If any, the contribution of the Chernobyl accident is negligible