Winter transport of Chernobyl radionuclides from a montane catchment to an ice-covered lake.

The amounts of 137Cs and 90Sr have been determined in the inflows and outflows of the Norwegian sub-alpine lake, Ovre Heimdalsvatn, in March/April during the period of ice-cover, when discharge is extremely stable. The lake is situated in an area contaminated by Chernobyl fallout. The transported course particulate plant material has been collected in traps; the particles and colloids have been removed from water samples by cross-flow ultrafiltration. On the basis of radionuclide inputs and outputs, lake budget calculations have been made for 137Cs and 90Sr during the period of ice-cover. Daily transport of radionuclides is considerably less than that observed during the spring snowmelt period when discharges are high. Size distribution patterns of Cs and Sr observed during winter are compared with previously published data from the same lake during the spring spate. The retention of 137Cs is similar in winter and spring, but retention of 90Sr is greater in winter.     

Performance of immobilized moss in the removal of 137Cs and 90Sr from actual low-level radioactive waste solutions

The efficiency of immobilized moss as a bio-sorbent for the removal of ¹³⁷Cs and ⁹⁰Sr radionuclides from actual low-level radioactive waste (LLW) solutions was investigated. Preliminary batch experiments with the moss (Funaria hygrometrica) for the sorption of Cs and Sr have shown a pH dependent binding trend from pH 1–13, with maximum binding between pH 5–10. Time dependence of the batch studies showed that a contact time of 30 minutes was sufficient to reach equilibrium. Column experiments for the sorption of Cs and Sr by moss after immobilizing in polymer silica matrix demonstrated that the sorbent is capable of removing considerable amounts of Cs and Sr from actual LLW solutions under constant flow conditions. The adsorption capacity was estimated to be 8.5 mg/g for Cs and 15 mg/g for Sr. These sorbed metal ions from the column could be leached out using 0.20M nitric acid. The regenerated sorbent exhibited relatively the same initial binding capacity of both Cs and Sr even after 3 cycles of reuse. This revised version was published online in July 2006 with corrections to the Cover Date.     

Separation of Ba and Pb from aqueous solutions of Sr with commercially available “precipitated active manganese dioxide”

Ba and Pb radionuclides can be removed from Sr in aqueous solution in both sodium acetate and acetic acid, containing 20 mg Sr carrier, by stirring with small (0.1–0.5 g) amounts of solid manganese dioxide. In tracer experiments⁸⁵Sr was separated with only small losses from¹³³Ba and²¹⁰Pb by separation factors of 87 and 135, respectively. The separation factor is defined here as the % of the initial⁸⁵Sr activity/ % of the initial¹³³Ba or²¹⁰Pb activity remaining in the aqueous phase after MnO₂ contact. The applicability of this technique for removing Ba and Pb radionuclides in the analysis of⁹⁰Sr in environmental samples (especially milk) is discussed.     

A sequential extraction scheme to ascertain the role of organic matter in radionuclide retention in Mediterranean soils

A sequential extraction scheme which indicates the role of organic matter in radionuclide retention was applied to two types of Mediterranean soil (sandy-loam and sandy), with low percentages of organic matter and with different contents of clay mineral, which had been previously contaminated with a radioactive aerosol, containing⁸⁵Sr,¹³⁴Cs and^110mAg. Different distributions were obtained for the three radionuclides, depending on the type of soil.⁸⁵Sr was the most available radionuclide for both types of soil, showing significant binding to organic matter in sandy-loam soil.¹³⁴Cs was the most retained radionuclide: for low-organic-matter soils, its availability seemed to depend on clay mineral content.^110mAg associated with available organic sites showed a positive correlation with organic matter content.     

Sorption of the long-lived radionuclides cesium-134, strontium-85 and cobalt-60 on bentonite

The sorption of long-lived radionuclides of cesium, strontium and cobalt (¹³⁴Cs, ⁸⁵Sr and ⁶⁰Co) on bentonite under various experimental conditions, such as contact time, pH, sorbent and sorbate concentrations have been studied. The uptake of Cs and Sr was rapid and equilibrium was reached almost instantaneously in both the cases, while Co sorption was time dependent. The sorption of these nuclides increased by increasing pH. The uptake of Cs, Sr and Co increased with increasing the amount of the bentonite clay. The percentage sorption for Cs, Sr and Co decreased with increasing metal concentrations. The desorption studies with 0.01M CaCl₂ and ground water at low-metal loadings on bentonite showed that about 95% of Cs, 85-90% of Sr and 97% of Co were irreversibly sorbed. These results could be helpful for nuclear waste management, for waste water effluents containing low concentrations of cesium, strontium and cobalt.     

Separation of137Cs and90Sr from mineralizates of biological materials by dicarbolide of cobalt

The distribution of some radionuclides in the course of¹³⁷Cs and⁹⁰Sr extraction and scrubbing between organic and water phase was determined.¹³⁷Cs and⁹⁰Sr were isolated from the mixture of radionuclides in mineralized biological materials. Dicarbolide of cobalt i. e. 3,3′-commo-bis[undecahydro-1,2-dicarbo-3-closo-dodecaborate] was used as an extracting agent. Quantities of the extracted radionuclides were determined by gamma spectrometric technique. Single and repeated extraction of⁹⁰Sr with 0.01M resp. 0.1M dicarbolide of cobalt in nitrobenzene and scrubbing of coextracted radionuclides by 0.5M HNO₃ were studied. The extraction of⁹⁰Sr was investigated from solutions of a hydrofobizing agent in the same way. Finally, the quantitative extraction of¹³⁷Cs followed by the extraction of⁹⁰Sr from mixtures of radionuclides in a mineralized biological material was studied. Extraction yields from dry and wet mineralizates of biological tissues, from urine and milk were compared. Suitable working conditions for the separation procedures were selected.     

Rasche S?ulentrennungen unter Verwendung eines oberfl?chlich sulfonierten Harzaustauschers

Zusammenfassung Die Verwendung oberflächlich sulfonierter Harzaustauscher hat die wesentlichen Vorteile, daß die Trennung sehr rasch und mit sehr verdünnten Elutionsmitteln erfolgen kann. Dies wird am Beispiel der Trennungen Na/Cs, Cs/Sr, Cs/Y, Ba/Cs und Sr/Y erläutert.

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Rapid column separations by means of a superficially sulphonated exchange resin

The use of superficially sulphonated ion-exchange resins has the essential advantages that the separations can be achieved very fast and with dilute eluents. Some examples of column separations (Na/Cs, Cs/Sr, Cs/Y, Ba/Cs, and Sr/Y) confirm this result.

     

Radionuclide mobility and bioavailability in Norwegian and Soviet soils.

A sequential extraction procedure has been applied to study the speciation of Chernobyl-derived radionuclides (137Cs and 90Sr) in soils from Norway, and from Byelorussia and the Chernobyl region in the USSR. Most 137Cs (greater than 80%) was strongly associated with soil components, whereas 90Sr was more mobile, up to 70% being found in the easily extractable fractions. The 90Sr: 137Cs ratio decreased with the distance from the reactor, reflecting the higher proportion of hot particles deposited in the regions close to the reactor, and the easily extractable fraction of 90Sr was significantly lower in the soils collected from the Chernobyl area. The distribution of stable Cs and stable Sr in the extraction fractions was similar for the various sites. Therefore, the location-specific differences in the distribution of 90Sr and, to a lesser extent, 137Cs arise because of fallout speciation rather than because of local environmental factors.     

Separation of 134Cs and 133Ba radionuclides by calcium alginate beads

The uptake behavior of long-lived radionuclides such as ¹³⁴Cs (2.06 years), ¹³⁷Cs (30 years) or ¹³³Ba (10.54 years) on calcium alginate (CA) beads have been investigated. The CA beads are able to remove ¹³³Ba (92%) at pH 7 after 90 min of exposure from the binary mixture of two. The separation method of short-lived daughter ¹³⁷Ba (2.55 min) from its long-lived parent ¹³⁷Cs (30 years) using this CA beads have also been developed.     

Behavior of <Superscript>134</Superscript>Cs, <Superscript>90</Superscript>Sr,and <Superscript>238</Superscript>Pu in different Syrian soils

The experiment aimed to evaluate the vertical migration of ¹³⁴Cs, ⁹⁰Sr and ²³⁸Pu in the main types of Syrian soils; entisol, inceptisol, alluvial (rock outcrops) and gypsiferous soils, using soil columns through which the aqueous solution of the radionuclides percolated. The results show that the vertical migration of the studied radionuclides through the soil profile depend on the radionuclide and the soil type. More than 97% of ¹³⁴Cs and ²³⁸Pu concentrated in the upper 2 cm of the entisol, inceptisol, and alluvial soils, whereas only 46.2% to 68.6% of the ⁹⁰Sr was retained in the upper 2 cm of these soils. The vertical migration of the studied radionuclides in the gypsiferous soil was different from the other soils. The distribution of the radionuclides in the gypsiferous soil was irregular through the soil profile and reached the deeper layer of the soil. This may be due to its physical characteristics; poor structure stability, high permeability and low retention capacity.     

Speciation of natural and antropogenic radionuclides in different sea sediment samples

A sequential extraction method consisting of six operationally-defined fractions was used to determine the geochemical partitioning of natural (U, Th,) and antropogenic (Pu, Am, ¹³⁷Cs) radionuclides in three sediment samples of different origin (Venice Lagoon, Adriatic Sea; Gaeta Gulf, Thyrrhenian Sea; IAEA-367, Enewetak Atoll, Central Pacific Ocean). Fe, Mn, Al, Ti, Ca, Sr, Pb, Ba, K were also determined in the different fractions to get more information about the chemical association of the single radionuclides. The experimental results were compared to those described in the literature for an IAEA-135 Sea Sediment collected in the Irish Sea in front of the Sellafield Plant (UK).     

Biosorptive behavior of some dead biomasses in the removal of Sr(85+89) from aqueous solutions

The knowledge of radioactive and stable elements partitioning to natural sediment systems is essential for modelling their environmental fate. A sequential extraction method consisting of six operationally-defined fractions has been developed for determining the geochemical partitioning of natural (U, Th, ⁴⁰K) and antropogenic (Pu, ²⁴¹Am, ¹³⁷Cs) radionuclides in a 10 cm deep sediment sample collected in the Tyrrhenian sea (Gaeta Gulf, Italy) in front of the Garigliano Nuclear Power Plant. ¹³⁷Cs and ⁴⁰K were measured by gamma-spectrometry. Extraction chromatography with Microthene-TOPO (U, Th), Microthene-TNOA (Pu) and Microthene-HDEHP (Am) was used for the chemical separation of the alpha-emitters: after electrodeposition alpha-spectrometry was carried out. Some stable elements (Fe, Mn, Al, Ca, Pb, Ba, Ti, Sr, Cu, Ni) were also determined in the different fractions to get more information about the chemical association of the radionuclides.     

Geochemical partitioning of actinides, 137Cs and 40K in a Tyrrhenian sea sediment sample: Comparison to stable elements

The knowledge of radioactive and stable elements partitioning to natural sediment systems is essential for modelling their environmental fate. A sequential extraction method consisting of six operationally-defined fractions has been developed for determining the geochemical partitioning of natural (U, Th, ⁴⁰K) and antropogenic (Pu, ²⁴¹Am, ¹³⁷Cs) radionuclides in a 10 cm deep sediment sample collected in the Tyrrhenian sea (Gaeta Gulf, Italy) in front of the Garigliano Nuclear Power Plant. ¹³⁷Cs and ⁴⁰K were measured by gamma-spectrometry. Extraction chromatography with Microthene-TOPO (U, Th), Microthene-TNOA (Pu) and Microthene-HDEHP (Am) was used for the chemical separation of the alpha-emitters: after electrodeposition alpha-spectrometry was carried out. Some stable elements (Fe, Mn, Al, Ca, Pb, Ba, Ti, Sr, Cu, Ni) were also determined in the different fractions to get more information about the chemical association of the radionuclides.     

Evaluation of the 153Sm-EDTMP radiochemical purity using three chromatographic methods

The knowledge of radioactive and stable elements partitioning to natural sediment systems is essential for modelling their environmental fate. A sequential extraction method consisting of six operationally-defined fractions has been developed for determining the geochemical partitioning of natural (U, Th, ⁴⁰K) and antropogenic (Pu, ²⁴¹Am, ¹³⁷Cs) radionuclides in a 10 cm deep sediment sample collected in the Tyrrhenian sea (Gaeta Gulf, Italy) in front of the Garigliano Nuclear Power Plant. ¹³⁷Cs and ⁴⁰K were measured by gamma-spectrometry. Extraction chromatography with Microthene-TOPO (U, Th), Microthene-TNOA (Pu) and Microthene-HDEHP (Am) was used for the chemical separation of the alpha-emitters: after electrodeposition alpha-spectrometry was carried out. Some stable elements (Fe, Mn, Al, Ca, Pb, Ba, Ti, Sr, Cu, Ni) were also determined in the different fractions to get more information about the chemical association of the radionuclides.     

A study on radionuclide association with soil components using a sequential extraction procedure

Measurements performed in 1986–1988 demonstrate that most of the radiocesium isotopes (¹³⁷Cs and¹³⁴Cs) deposited after the Chernobyl accident are still located in the upper soil layers (0–2 cm). The vertical migration appears to be slow, and only a small fraction of the radiocesium has been transferred into the biological cycle. Sequential extraction techniques have been utilized in order to investigate the degree of binding or association between deposited radionuclides (¹³⁷Cs,¹³⁴Cs and⁹⁰Sr) and components in soil. The results indicate that a major fraction of the radiocesium is associated strongly with organic and mineral materials in the litter or upper soil layers: less than 10% is easily leachable. The distribution of¹³⁷Cs throughout the fractions was similar to that determined for naturally occurring stable cesium (¹³³Cs), implying that isotopic exchange had been extensive. For⁹⁰Sr, the results show a relatively high leachable fraction. Therefore, present results indicate that radiocesium should be less mobile, and less available for root uptake, than⁹⁰Sr in soil.     

Radiochemical determination of Caesium-137, strontium-89,90 and barium-140 in milk and bone ash

Summary A method for the determination of radiocaesium, radiostrontium, radiobarium in milk and bone ash is described. An alkaline fusion of ash followed by leaching with water provides for the preliminary separation of radiocaesium. After dissolution of leaching residue in hydrochloric acid and sorption on Dowex 50 W, X-8, radioyttrium (rare earths fission products), magnesium and calcium are eluted with 1.0 M ammonium lactate, pH 7.5. Radiostrontium, radiobarium and radium are separated by elution with 0.15 M ammonium citrate, pH 7.5. ¹³⁷Cs is isolated as Cs-dipicrylaminate, ⁸⁹Sr/⁹⁰Sr as SrCO₃, ¹⁴⁰Ba as BaCO₃ and counted on a low-background beta-counter. For determined radionuclides the average chemical yields amount to 80%. The limits of detection for ¹³⁷Cs, ⁹⁰Sr, ¹⁴⁰Ba are 0.02 pCi/g with a 10 g sample of milk ash and 0.04 pCi/g with a 4 g sample of bone ash, respectively.

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Radiochemische Bestimmung von Caesium-137, Strontium-89,90 und Barium-140 in Milch- und Knochenasche

Zusammenfassung Zur Vorabtrennung von Radio-Caesium wird die Ascheprobe alkalisch geschmolzen und dann mit Wasser ausgelaugt. Nach Auflösung des ausgelaugten Rückstandes in Salzsäure und Sorption an Dowex 50 W, X-8 werden Yttrium (Spaltprodukte der Seltenen Erden), Magnesium und Calcium mit 1,0 M Ammoniumlactat, pH 7,5 eluiert. Radio-Strontium, Radio-Barium und Radium werden durch Elution mit 0,15 M Ammoniumcitrat, pH 7,5, abgetrennt. ¹³⁷Cs wird als Cs-Dipikrylaminat isoliert, ⁸⁹Sr/⁹⁰Sr als SrCO₃,¹⁴⁰Ba als BaCO₃; gemessen wird in einem Beta-Antikoincidenzzähler. Für die bestimmten Radio-Nuklide beträgt die durchschnittliche Rückgewinnung 80%. Die unteren Nachweisgrenzen für ¹³⁷Cs, ⁹⁰Sr, ¹⁴⁰Ba betragen bei einer 10 g-Milchasche-Probe 0,02 pCi/g und bei einer 4 g-Knochenasche-Probe 0,04 pCi/g.

     

Prediction capacity of a sequential extraction scheme

The predictions of a sequential extraction scheme with respect to the mobility of some radionuclides (⁸⁵Sr,¹³⁴Cs and^110mAg) in two Mediterranean sandy and sandy-loam soils, are compared to short-term soil-to-plant transfer factors and soil migration. Total soil-to-plant transfer is higher in sandy soil than in sandy-loam soil, as expected and predicted by the scheme. The relative transfer to plants of¹³⁴Cs and⁸⁵Sr follows the scheme predictions about exchangeable radionuclide fraction, radiosilver being less mobile than expected. Migration in soil of radiocesium and radiostrontium is also higher in sandy soil, especially for the latter radionuclide, the relative behavior of these two radionuclides being nearer to the bioavailable radionuclide fraction defined by the scheme. However, the scheme fails in predicting radiosilver migration, which is lower than deduced by the scheme.     

On the separation of cesium and strontium from oxalate filtrate by neutralization

At the treatment of HLLW (high-level liquid radioactive waste) by oxalate precipitation, the filtrate is occured as a waste. But various elements including Cs and Sr are contained in the oxalate filtrate. It is very important, therefore, to separate from each other in a viewpoint of ultimate isolation of heat generating nuclides such as Cs and Sr from HLLW. In this study, the simulated oxalate filtrate, consisted of five elements (Cs, Sr, Ru, Fe and Mo) and organics (oxalic acid and ascorbic acid), was prepared, from which the separation of Cs and Sr was carried out by neutralization with NaOH. As a result, the simulated solution could be divided into Cs, Sr and Ru containing groups with pH. Sr was readily precipitated as forms of Sr(C₂O₄)·nH₂O at pH 3. Iron and ruthenium were also co-precipitated around pH 8, and Cs and Mo remained in the resulting solution.     

INAA of geological materials using a combination of epithermal activation and Compton suppression: Prediction of possibilities

Nuclear data relevant to the determination of elements in geological materials by instrumental neutron activation analysis using a combination of epithermal neutron activation and Compton suppression counting are presented. The feasibility of this combination is discussed considering data for desired as well as interfering nuclides. Among elements determined after short irradiation, the conditions for Sr, Zr, I, Cs, Eu and U should be improved. After long epithermal irradiation and appropriate decay, Compton suppression should lead to improvement in determination of As, Rb, Sr, Mo, Sn, Sb, Ba, Gd, Ho, Tm, W, Au, Th, and U. In the case of Ga, Se, Ag, In, Cs, Tb, Yb, Hf, Ta, and W, the use of Compton suppression in connection with epithermal activation is not recommended because the radionuclides concerned decay with coincident γ-rays. In general, the use of Compton suppression should improve the determination of trace elements in geological materials by epithermal neutron activation analysis, but more work is needed to better quantify these improvements.     

A review of the studies on environmental transport and speciation analysis of radionuclides in India

Department of Atomic Energy, India, has a systematic environmental monitoring program to ensure that the impact of radionuclides on human and environment is well within the limits, stipulated by the regulatory body. Concentrations of radionuclides are estimated in air, water, soil, sediment and biota in the environment around the power plant site on a regular basis. The environmental migration pattern and impact of radionuclides in the environment depends upon not only on the total concentration but the physico-chemical nature of radionuclide also. This paper presents a brief review of the studies of environmental transportation of radionuclides and influence of speciation with special reference to Indian conditions. A fairly good amount of results are available on the influence of speciation of radionuclides on the wet and dry deposition and preliminary results are available on the speciation analysis in dietary items, in soil and in ground water. Initial studies are concentrated on tritium, ¹³⁷Cs, Uranium, ⁹⁰Sr and their chemical analogues.