Biokinetics of Americium-241 in the euryhaline diamond sturgeon Acipenser gueldenstaedtii following its uptake from water or food.

Americium-241 whole body and internal biokinetics were experimentally investigated in the euryhaline diamond sturgeon Acipenser gueldenstaedtii during its uptake from water and food, in fresh (FW) and brackish water (BW; 9 psu). Whole-body uptake rates of 241Am from water and subsequent depuration rates were quantified over 14 and 28 days, respectively, and assimilation efficiency (AE) of 241Am from diet (chironomid) was determined over 28 days. FW reduced the biological half-life of 241Am following aqueous uptake by an order of magnitude. In contrast BW greatly reduced 241Am assimilation efficiency (AE) from diet (chironomid) by several orders of magnitude (from an AE of 8.5% (FW) down to 0.003% (BW)). Hence, salinity per se is indicated as a major environmental variable in determining the radiological exposure of A. gueldenstaedtii to 241Am. During aqueous exposure BW appreciably increased 241Am activity concentrations in most body components, but aqueous or dietary exposure pathway at either salinity did not determine marked differences in how 241Am was distributed among six body components. The highly mineralized skin of A. gueldenstaedtii recurred as a major repository of 241Am in all experimental treatments, as high as 50% among body components, due to its internal transfer from diet, surface adsorption and/or active absorption from water. The indicated prominence of the aqueous, compared to the dietary, exposure pathway for 241Am accumulation by A. gueldenstaedtii suggests its radiological exposure would be enhanced by BW as it leads to its greater long-term retention, due to a much longer biological half-life.

Investigation of the distribution of transuranic radionuclides in marine sediment at the Montebello Islands, Western Australia.

Three nuclear weapons tests were conducted in the 1950s at the Montebello Islands, Western Australia. The detonations were of different yields and configurations (two tower tests, one ship test), and led to substantial radionuclide contamination within the surrounding terrestrial and marine ecosystems. The region possesses great ecological and recreational significance, particularly within the marine environment. However, studies conducted so far have largely neglected the marine ecosystem which makes up the majority of the Montebello Island Marine Park and in which most test fallout would have deposited. Here we investigated the distribution of the transuranic radionuclides 238Pu, 239,240Pu and 241Am in marine sediment from the Montebello Islands. Marine sediment samples near Operation Mosaic G2 and Operation Hurricane were collected and analysed by gamma and alpha spectrometry. Activity concentrations of 239,240Pu across both series ranged from 45 to 2900 Bq kg-1, while 241Am levels ranged from 2.8 to 70 Bq kg-1. Higher activity concentrations were observed in sediment near the land-based, higher yield Mosaic G2 test, compared with the ship-based, lower yield Hurricane test. Sediment samples located closer to the detonation site were also observed to have higher activity concentrations. Radioactive particles of 0.94 mm and 1.5 mm in diameter were identified by analysis of size-fractioned sediment via investigation of 152Eu levels, photostimulated autoradiography and point gamma spectroscopy. Particles were confirmed to have transuranic radionuclide interiors, with surface coatings which were dominated by vitrified CaCO3. Their long-term resistance to weathering and subsequent persistence in the marine environment can therefore be attributed to their coated structural form. Our study confirms the persistence of transuranic radionuclides in Montebello Island marine sediment and highlights the need for additional studies to improve our understanding of the nuclear legacy in this region.

Characterization of typical transuranic nuclides in a reference fallout material using SF-ICP-MS.

For the quality control in determining transuranic nuclides in fallout samples, this work first reported the 237Np activity concentration in a reference fallout material and further calculated the activity ratios of 237Np/239+240Pu and 237Np/241Am, and the atom ratio of 237Np/239Pu in it. The reference fallout material prepared by the Meteorological Research Institute was collected at 14 stations throughout Japan in 1963-1979. The 237Np and Pu isotopes (239Pu and 240Pu) were separated and purified using AG MP-1M anion-exchange resin, quantified using 242Pu as an isotope dilution tracer, and determined by the SF-ICP-MS. The analytical method was validated by the analysis of 4 sediment reference materials. The activity concentrations of 237Np, 239Pu and 240Pu were (25.9 ± 0.6) × 10-3, 4.10 ± 0.01 and 2.89 ± 0.04 Bq/kg, respectively, in the investigated reference fallout material. The activity ratio of 237Np/239+240Pu (3.7 ± 0.1) × 10-3 was consistent with the global fallout evaluation value. The 237Np/239Pu atom ratio of 0.561 ± 0.014 was higher than the average global fallout value of 0.41 ± 0.010, indicating the necessity of establishing regional characteristic global fallout value of 237Np/239Pu atom ratio for assessment of radioactive contamination. Comparison of the 237Np/239+240Pu activity ratios between in the reference fallout material and in soils over several decades indicated that 237Np has stronger migration capability than Pu isotopes in soils because 237Np was depleted compared to reference fallout material.

Decontamination of Actinide-contaminated Injured Skin with Ca-DTPA Products Using an Ex Vivo Rat Skin Model.

ABSTRACT: Skin contamination by α-emitting actinides such as plutonium and americium is a risk for workers during nuclear fuel production and reactor decommissioning. Decontamination of skin is an important medical countermeasure to limit potential internal contamination, particularly in the case of injured skin. Current recommendations include undressing of the victim followed by skin washing using soap or chelating agents, such as diethylene triamine pentaacetic acid (DTPA). The goal of the present work is to assess the efficacy of a novel Ca-DTPA loaded gel to decontaminate injured skin exposed to plutonium or americium as compared to recommended treatments. For decontaminant testing on injured skin, whole body skin was obtained from euthanized rats and lesions created using a metallic brush. Delimited test areas were contaminated with plutonium or americium solutions of known properties. Various protocols were tested including time before contamination, duration of gel application, washing steps, as well as the concomitant addition or not of dressings. Activity was measured in each decontamination product and in skin. Data indicate that healthy skin was easier to decontaminate than damaged skin. On injured skin, we demonstrated an increased decontamination efficacy of the Ca-DTPA gel formulation as compared to the solution. Importantly, gel application alone was effective, and further gel applications could be used for residual activity.

Estimation of 241Am and 239Pu activity embedded in the tissue using portable planar HPGe detector.

This paper describes a procedure for the estimation of 241Am and 239Pu activity present in the human tissue by measuring the depth of contaminant using a portable Planar High Purity Germanium detector (HPGe). The ratios of photopeak counts of X-rays or gammas obtained with the detector coupled to collimator are calculated for the estimation of depth of the contaminant and the optimum one is determined. Since Minimum Detectable Activities (MDA) for the detector coupled to a collimator are higher than that of bare detector, activity must be estimated using bare detector, after locating the contaminant. Two methods are described for the estimation of plutonium coexisting with 241Am: (i) Abundance and isotopic correction for 239Pu (ii) and 239Pu:241Am ratio. The procedure to estimate 239Pu when plutonium isotopes alone are present is also established. An optimum monitoring period to detect the minimum value of intake for both radionuclides corresponding to chelation therapy and excision is also derived.

Vertical distribution of 241Am in the southern Baltic Sea sediment profiles.

The contamination of the Baltic Sea with radioactive substances occurred due to the global fallout of atmospheric nuclear weapon tests and the Chernobyl disaster. The knowledge of 241Am in the sediments of the Baltic Sea is limited. Thus, this study aimed to determine 241Am in sediment cores collected from the southern Baltic Sea. Time-based distributions were derived from age-depth profiles using the 210Pb dating method and further corroborated by 137Cs profiles. The activities of 241Am were measured by alpha spectrometry after radiochemical purification. The results show divergences in the concentrations of 241Am at the local level, varying from 0.017 ± 0.001 Bq·kg-1 at the Gotland Basin station to 3.19 ± 0.23 Bq·kg-1 in the Gdansk Basin. These findings enhance our understanding of the radioactive contamination levels in the Baltic Sea and serve as a crucial reference dataset for future assessments and management strategies to mitigate the environmental impact of radionuclides in the region.

Adsorption-desorption of 241Am(â ¢) on montmorillonite colloids and quartz sand: Effects of pH, ionic strength, colloid concentration and grain size.

Clay colloids in the subsurface environment have a strong adsorption capacity for radionuclides, and the mobile colloids will carry the nuclides for migration, which would promote the movability of radionuclides in the groundwater environment and pose a threat to the ecosphere. The investigations of the adsorption/desorption behaviors of radionuclides in colloids and porous media are significant for the evaluation of the geological disposal of radioactive wastes. To illustrate the adsorption/desorption behaviors of 241Am(Ⅲ) in Na-montmorillonite colloid and/or quartz sand systems at different pH (5, 7 and 9), ionic strengths (0, 0.1 and 5 mM), colloid concentrations (300 and 900 mg/L), nuclide concentrations (500, 800, 1100 and 1400 Bq/mL) and grain sizes (40 and 60 mesh), a series of batch sorption-desorption experiments were conducted. Combining the analysis of the physical and chemical properties of Na-montmorillonite with the Freundlich model, the influencing mechanism of different controlling factors is discussed. The experimental results show that the adsorption/desorption behaviors of 241Am(Ⅲ) in Na-montmorillonite colloid and/or quartz sand strongly are influenced by the pH value and ionic strength of a solution, the colloid concentration as well as quartz sand grain size. The adsorption and desorption isotherms within all the experimental conditions could be well-fitted by the Freundlich model and the correlation coefficients (R2) are bigger than 0.9. With the increase in pH, the adsorption partition coefficient (Kd) at 241Am(Ⅲ)-Na-montmorillonite colloid two-phase system and 241Am(Ⅲ)-Na-montmorillonite colloid-quartz sand three-phase system presents a trend which increases firstly followed by decreasing, due to the changes in the morphology of Am with pH. The Kd of 241Am(Ⅲ) adsorption on montmorillonite colloid and quartz sand decreases with increasing in ionic strength, which is mainly attributed to the competitive adsorption, surface complexation and the reduction of surface zeta potential. Additionally, the Kd increases with increasing colloid concentrations because of the increase in adsorption sites. When the mean grain diameter changes from 0.45 to 0.3 mm, the adsorption variation trends of 241Am(Ⅲ) remain basically unchanged. The research results obtained in this work are meaningful and helpful in understanding the migration behaviors of radionuclides in the underground environment.

Co-transport behavior of Am(III) and natural colloids in the vadose zone sediments.

Americium (III) (Am(III)) in the natural environment is considered immobile due to its low solubility, strong adsorption, and high affinity to solid surfaces. However, the presence of natural colloids may carry Am(III) transport for long distance. The individual and co-transport behaviors of Am(III) and natural colloids through the unsaturated packed columns were investigated under the influence of pH, electrolyte concentration, velocity, Am(III) concentration and natural colloids concentration. Under all experimental conditions, Am(III) individual transport construct sight breakthrough curves (BTCs, CAm/C0 < 3%), but the presence of natural colloids increased the BTCs plateau of Am(III) significantly (30% < CAm/C0 < 80%), indicating that the colloids were able to promote Am(III) transport in the unsaturated porous media. DLVO theoretical calculations reveal that the increased pH and decreased electrolyte concentration lead to a rase in electrostatic repulsion, and the natural colloids tend to be dispersed and stabilized, which facilitates elution. In addition to this, the increase of velocity and colloids concentration will lead to greater breakthrough of natural colloids. The non-equilibrium two-site model and the two-site kinetic retention model well-described the BTCs of Am(III) and natural colloids, respectively. This study provide new insights into the behavior of natural colloids carrying the Am(III) into aquifers through the vadose zone sediments.

3D Printed Lung Phantom for Individual Monitoring.

ABSTRACT: The Human Monitoring Laboratory, Health Canada (HML), has used a 3D printer to re-engineer its Lawrence Livermore National Laboratory (LLNL) foam lung sets (manufactured by Radiology Support Devices, Inc., Long Beach, CA). The foam sets are currently the HML standard for calibrating and performance testing lung-counting systems in Canada. This paper describes the process of creating and validating new 3D-printed lung sets modeled from one of the HML's existing RSD foam sets. The existing sets were custom made, making them costly and difficult to obtain or replace. Also, after many years of use, the HML has found that they are prone to wear and tear. When used with planar inserts containing various isotopes, the blank sets can become contaminated and are difficult to clean. Using 3D printing, the HML has created new blank lung sets that are nearly identical copies of the originals and are inexpensive and easily manufactured. Measurements using natural uranium (Nat U), 241Am, and 152Eu planar lung inserts were performed to compare obtained efficiencies at a wide range of energies using the original RSD foam sets and the 3D-printed ones. Both the foam and the 3D-printed lung sets were counted using the LLNL chest phantom positioned in the same counting geometry in the lung counting system. Biases, all below 15%, were obtained between the foam and the 3D-printed sets for energies above 40 KeV. Based on these results, as well as cost benefits and ease of use, the HML has decided to replace its original RSD foam lung set with the 3D-printed version for its lung performance testing program.

A multi-collector ICP-MS method for quantification of plutonium, uranium, and americium in hair and nails of occupationally or medically exposed individuals.

The 239Pu, 238U, and 241Am concentrations and 239Pu/240Pu, 235U/238U, and 236U/238U atom ratios were measured in the hair and nail samples using a new method utilized TEVA, UTEVA, and DGA extraction chromatography and multi-collector ICP-MS. Samples were collected from individuals who donated their bodies to the United States Transuranium and Uranium Registries. The concentration of 239Pu ranged from 0.22 to 15.8 ng/kg. The 240Pu/239Pu isotopic ratios ranged from 0.026 to 0.127 which is consistent with weapons-grade plutonium. Concentration of uranium fell between 1.84 µg/kg and 29.5 µg/kg and 235U/238U ratios ranged from 4.8 × 10-3 to 7.6 × 10-3. Elevated 236U/238U atom ratios were measured in two cases and ranged from 5.0 × 10-6 - 2.4 × 10-5 indicating exposure to spent or reprocessed uranium material. The concentration of 241Am was measured in four hair samples and ranged from 0.02 to 0.21 ng/kg.

Bioaccumulation of radionuclides in hoofed animals inhabiting the Semipalatinsk Test Site.

The article assesses the content of radionuclides in hoofed animals inhabiting the Semipalatinsk Test Site by calculation. Hoofed animals' faeces were sampled to determine the content of radionuclides in their diets. Based on values determined for the content of radionuclides in animals; diets, the content of radionuclides in the meat and milk of farm animals-cows (Bos taurus taurus), sheep (Ovis), goats (Capra hircus) and horses (Equus caballus Lin., 1758) as well as in the meat of wild animals-european moose (Alces alces Lin., 1758), argali (Ovis ammon Lin., 1758), roe deer (Capreolus pygargus Pal., 1771) and saiga (Saiga tatarica Lin., 1766) was calculated. No excess of permissible values of the content of 137Cs and 90Sr in the meat of farm animals was found to be expected, even for a conventional 'conservative' scenario, in which maxima of the radionuclide activity concentration in a vegetable feed (faeces) are taken as a basis. 241Am and 239+240Pu in the meat of farm hoofed animals are not standardized. Their predicted maxima of activity concentration are very low, and even in the 'conservative' scenario, they do not exceed 1.8×10-2 Bq kg-1, 1.4×10-1 Bq kg-1 and 1.6×10-1 Bq kg-1, respectively. In the milk of farm animals, the content of 137Cs and 90Sr does not exceed permissible values. 241Am and 239+240Pu in the milk of farm animals are not standardized. Their predicted activity concentration values in the milk of sheep and goats do not exceed 6.5×10-2 Bq l-1, for cows- 2.6×10-2 Bq l-1, for horses- 3.1×10-2 Bq l-1. Permissible values of 137Cs and 90Sr in the meat of wild hoofed animals are not exceeded either. In the meat of argali, roe deer and saigas, relatively high levels of 137Cs are predictable. 241Am and 239+240Pu in meat of wild animals are not standardized. Their predicted activity concentration values in the meat of moose and argali do not exceed 3.2×10-1 Bq kg-1 and 1.6×10-1 Bq kg-1, respectively, for roe deer and saiga-5.4×10-2 Bq kg-1. Thus, in case of free grazing in the STS territory, no excess of permissible values of standardized radionuclides (137Cs and 90Sr) in the meat and milk of hoofed animals is predictable.

Development of a new integrated IN-VIVO counting system at the QST.

A new in-vivo counting system that functions as both a whole-body counter (WBC) and a lung counter (LC) was developed at the QST to enhance its dose assessment capability. This paper presents an overview of this system and the results of its performance tests. For use of the system as a WBC, three high purity germanium (HPGe) detectors installed in a 20-cm-thick iron shielding chamber are linearly arrayed over a subject lying on the bed, whereas two of the three HPGe detectors are placed over the subject's chest from side to side when using the system as an LC. The new in-vivo system was calibrated using three de-facto phantoms owned by the QST: an adult-male BOttle Manikin ABsorption (BOMAB) phantom, a Lawrence Livermore National Laboratory (LLNL) phantom and a Japan Atomic Energy Research Institute (JAERI) phantom. Monte Carlo simulations were also performed to determine an optimum location for the three detector array in the WBC mode and revealed that the peak efficiency for the BOMAB phantom (662 keV) was little varied as long as the middle detector was placed above the thorax and abdomen parts of the phantom. The calculated peak efficiencies agreed well with the observed peak efficiencies for photons with energies over 100 keV. For lung counting, a tentative Minimum Detectable Activity of 241Am was evaluated as 9.5 Bq for a counting time of 30 minutes, and a Japanese male subject with an average chest wall thinness (2.27 cm). The developed system is now ready for use.

Biokinetic model analysis with DTPA administration for a case of accidental inhalation of actinides in Japan.

Accidental inhalation intake of plutonium isotopes and 241Am occurred at a Pu research facility in Japan in 2017, and the five workers involved in this accident were treated by the administration of Ca/Zn-diethylenetriaminepentaacetic acid (DTPA). For the worker who was most internally exposed, the therapy was continued over 1 y after the accident. Urinary samples collected before and after each administration were subject to bioassay to evaluate the efficacy of the dose reduction. This study performed numerical analyses using a biokinetic model dealing with 241Am-DTPA with reference to the European Coordinated Network on Radiation Dosimetry approach, which assumes that the complex of actinides and Ca/Zn-DTPA is generated in the designated compartments in the biokinetic model. The results of the model prediction well captured the trend of the observed urinary excretion in the long-term bioassay and would be useful to evaluate the efficacy of the Ca/Zn-DTPA administration for the worker involved in the accident.

Source efficiency of alpha-emitters applied to the skin surface.

Skin surface contamination by alpha-emitters is in itself not hazardous, but it would cause significant internal exposure in the case of injured skin as well as misjudgment in direct in vivo measurements (e.g. lung counting). The present study determined the source efficiency of alpha-emitters (241Am) applied to swine skin samples by analysing the observed alpha-particle energy spectra using advanced alpha-spectrometric simulation. Based on our results, the source efficiency was determined to be 0.365 (alpha-particle s-1 per Bq) on average (c.f. 0.5 in the case of no self-absorption in the source). The decrease in source efficiency would be attributed primarily to the radionuclide entering hair follicles or deep wrinkles. The degradation of the measured spectra from the skin samples indicates the penetration of some radionuclides into the upper layers of the stratum corneum. Although this study was limited to results obtained from swine skin samples, it suggests that irregularities in the skin surface may affect direct alpha measurements.

Modelling DTPA therapy following Am contamination in rats.

A major challenge in modelling the decorporation of actinides (An), such as americium (Am), with DTPA (diethylenetriaminepentaacetic acid) is the fact that standard biokinetic models become inadequate for assessing radionuclide intake and estimating the resulting dose, as DTPA perturbs the regular biokinetics of the radionuclide. At present, most attempts existing in the literature are empirical and developed mainly for the interpretation of one or a limited number of specific incorporation cases. Recently, several approaches have been presented with the aim of developing a generic model, one of which reported the unperturbed biokinetics of plutonium (Pu), the chelation process and the behaviour of the chelated compound An-DTPA with a single model structure. The aim of the approach described in this present work is the development of a generic model that is able to describe the biokinetics of Am, DTPA and the chelate Am-DTPA simultaneously. Since accidental intakes in humans present many unknowns and large uncertainties, data from controlled studies in animals were used. In these studies, different amounts of DTPA were administered at different times after contamination with known quantities of Am. To account for the enhancement of faecal excretion and reduction in liver retention, DTPA is assumed to chelate Am not only in extracellular fluids, but also in hepatocytes. A good agreement was found between the predictions of the proposed model and the experimental results for urinary and faecal excretion and accumulation and retention in the liver. However, the decorporation from the skeletal compartment could not be reproduced satisfactorily under these simple assumptions.

Minor Actinides Can Replace Essential Lanthanides in Bacterial Life.

Certain f-block elements-the lanthanides-have biological relevance in the context of methylotrophic bacteria. The respective strains incorporate these 4 f elements into the active site of one of their key metabolic enzymes, a lanthanide-dependent methanol dehydrogenase. In this study, we investigated whether actinides, the radioactive 5 f elements, can replace the essential 4 f elements in lanthanide-dependent bacterial metabolism. Growth studies with Methylacidiphilum fumariolicum SolV and the Methylobacterium extorquens AM1 ΔmxaF mutant demonstrate that americium and curium support growth in the absence of lanthanides. Moreover, strain SolV favors these actinides over late lanthanides when presented with a mixture of equal amounts of lanthanides together with americium and curium. Our combined in vivo and in vitro results establish that methylotrophic bacteria can utilize actinides instead of lanthanides to sustain their one-carbon metabolism if they possess the correct size and a +III oxidation state.

THE IMPACT OF NEW ICRU95 QUANTITIES AND SPECTRUM DATA ON THE DOSIMETRIC QUANTITIES OF THE NEUTRON REFERENCE FIELDS AT PTB.

In 2020, the ICRU released a new report which includes the re-definition of the operational quantities used in radiation protection and new conversion coefficients from physical quantities to operational radiation protection quantities. An assessment of the ambient and personal dose conversion coefficients for the reference neutron fields of radionuclide sources at PTB is necessary based on these new definitions. In this work, a numerical estimation of the conversion coefficients of moderated and unmoderated 252Cf and 241Am-Be neutron sources based on ICRU57 and ICRU95 reports and using spectrum data available in the ISO 8529-1 standard and at PTB are discussed. Two numerical approaches are used for this estimation to ensure the reliability of the calculated values: a direct calculation using MCNP6, and cubic interpolation of conversion coefficients datasets written in Python. The results show large differences between the spectrum-averaged operational quantities for the current and new conversion coefficients of up to 23%. The choice of spectrum data affects conversion coefficient values by 6-8%.

THE NATIONAL RESEARCH COUNCIL OF CANADA MANGANESE BATH SYSTEM.

The manganese salt bath is considered a primary standard for determining the absolute emission rate of radionuclide neutron sources. The National Research Council of Canada has recently revived its manganese salt bath and a full description of the system is given here. The physical characteristics of the bath, as well as the methods for determining the efficiency of the bath system and the induced activity in the bath, are described. An in-depth analysis of the fraction of neutrons captured in the manganese and the correction factor for neutron losses is also provided. Finally, the results of emission rate measurements of four different sources, complete with an uncertainty budget, are given. The emission rates of three americium-beryllium neutron sources and one californium-252 neutron source were found to agree with the known values, within a standard uncertainty of 1.7%.

Vertical distribution of radionuclides in soil at the Semipalatinsk Test Site beyond its test locations.

Data on the vertical distribution of radionuclides in the soil is necessary to fully understand the radioecological situation around ecosystems, give predictive estimates to how safe crop products are and justify a rehabilitation strategy for radioactively contaminated areas. A study was conducted to investigate the vertical distribution of radionuclides in soils of the former Semipalatinsk Test Site (STS) territory beyond its testing sites, that is, in areas in which no nuclear weapons or nuclear effects of radiological warfare agents were tested. Soil was sampled layerwise all over the Semipalatinsk Test Site down to 30 cm deep at a 5-cm spacing. Most of high activity concentrations of radionuclides all over the study area were detected in the 0-5 cm soil layer. Activity concentrations of the major man-made radionuclides were determined in soil samples collected by γ-, ß and α-spectrometry. As a result, ranges of activity concentrations of 137Cs, 241Am, 90Sr and 239+240Pu were determined in 0-5, 5-10, 10-15, 15-20, 20-25, 25-30 cm soil layers. In the conventionally 'background' area, the 0-5 cm soil layer, on average, contains (the percentage of total activity concentration across the soil profile depth): 137Cs- 83%, 239+240Pu- 87% and 90Sr- 38%. For the 1953 plume, these values were 92%, 83% and 73%, respectively. Values for the 1951 plume in the 0-5 cm soil layer were: 137Cs- 93%, 239+240Pu- 93% and 90Sr- 59%. The minimum concentration of radionuclides are observed 20-30 cm deep in all areas studied. 90Sr is the most mobile radionuclide from the perspective of its ability to travel deep down the soil. The study found out that the nuclide vertical migration rates downward in soils based on detected activity were as follows (in descending order): 90Sr- 137Cs- 239+240Pu- 241Am. Coefficients that determine the ratio of the activity concentration of the radionuclide in the 0-20 and 0-30 cm soil cover layers to that of this radionuclide in the 0-5 cm topsoil were calculated. These coefficients enable to estimate the radionuclide inventory at each soil sampling point from their activity concentration in the 0-5 cm soil layer.

Experimental assessment of 241Am accumulation in Carassius gibelio from amphipods.

Accumulation of dietary 241Am in freshwater omnivorous fish (Carassius gibelio) was studied aiming to estimate the distribution and retention of 241Am in the fish body. Amphipods labeled with 241Am served as a food item. From 0.4 to 0.6% of ingested 241Am was retained in the fish body after short courses of feeding and depuration, the trophic transfer factor of 241Am for whole organism level was about 2∙10-4.