Plutonium,241Am,90sr,and137cs concentrations in some antarctic matrices

A radioecological survey in Antarctica shows that the^239+240Pu,²³⁸Pu,²⁴¹Am,⁹⁰Sr, and¹³⁷Cs activities were detectable in nearly all the samples. The activity level of^239+240Pu,²⁴¹Am, and¹³⁷Cs in antarctic sediments was about 5–20 times lower than in the northern Adriatic Sea sediments, but the²³⁸Pu activities were relatively high. It was interesting to note that the⁹⁰Sr concentrations in all the sediments tended to be low, which could be the result of the easier exchangeable behavior of⁹⁰Sr in water. High concentrations were detected in mosses and lichens and their activity levels were comparable to those in central Italy. The radionuclide ratio analyses show that the major part of^239+240Pu,²⁴¹Am,⁹⁰Sr, and¹³⁷Cs was a result of nuclear weapon tests. The higher²⁴¹Am/^239+240Pu ratio was observed and it could perhaps be the result of fallout of nuclear weapon tests prior to 1962. The²³⁸Pu/^239+240Pu ratio in the antarctic matrices was about seven times higher than in the Northern hemisphere and it could be inferred that the major part of²³⁸Pu was originating from the SNAP-9A satellite accident.     

Solubility of airborne radioactive fuel particles from the Chernobyl reactor and implication to dose

Airborne particles of nuclear fuel from the Chernobyl reactor that had been collected on air filters and stored, were characterised using in vitro dissolution tests to assess effective doses after their inhalation. As solvent, the Gamble biological fluid was used to simulate lung fluid. The solubility of the measured radionuclides decreased in the order ¹³⁷Cs>⁹⁰Sr>>²⁴¹Am^239+240Pu in the simulated lung fluid. The dissolution rate constant of e.g. ^239+249Pu ranged from 0.72 to 5.4×10^–6 g·cm^–2 d^–1 and decreased (for all nuclides) with increasing particle size as predicted from theoretical considerations. Considering the inhalation dose, decreasing dose with size and increasing doses with lower solubility may partly counterbalance each other for ¹³⁷Cs and ⁹⁰Sr. On the other hand, for ²³⁹Pu and ²⁴¹Am larger particles and associated lower solubility both change the resulting dose in the same direction towards lower values. The comparison of the experimentally determined dose coefficients with ICRP values indicates that nuclear fuel particles closely resemble type M material characteristics for ¹³⁷Cs and ⁹⁰Sr and type S material characteristics for ²³⁹Pu and ²⁴¹Am.     

Radioactive aerosols released from the Chernobyl Shelter into the immediate environment

The release of radioactive particles through large gaps in the containment of the destroyed Chernobyl reactor was assessed during two measurement periods. In 1996–1999, a total radionuclide flow rate of 274 Bq s⁻¹ or 8.64 × 10⁹ Bq year⁻¹ was determined. These releases were predominantly due to ¹³⁷Cs (78.5%), ⁹⁰Sr (21.1%), and ^239+240Pu (0.4%). The mean activity concentration in the aerosol measured directly at the gaps was about 240 mBq m⁻³ with an activity median aerodynamic diameter (AMAD) of 2.4 μm for ¹³⁷Cs, 120 mBq m⁻³ with an AMAD in the range 3.1–13 μm for ⁹⁰Sr, 1.8 mBq m⁻³ with an AMAD in the range 3.5–11 μm for ^239+240Pu, and 2.0 mBq m⁻³ with an AMAD of 1.5 μm for ²⁴¹Am. The resulting total inhalation dose rate calculated close to the gaps was about 100 nSv h⁻¹. In the near environment, the mean ¹³⁷Cs activity in the aerosol was 2.2 mBq m⁻³ with an AMAD of 2.2 μm, which gave rise to an inhalation dose rate of about two orders of magnitude lower than the corresponding dose rate at the gaps. Occasionally, however, dose levels were measured in the near environment that were similar to those at the gaps. In 2000–2003, lower activity concentrations were observed. The decrease was more pronounced at the gaps than in the near environment. The results indicate that effective dose due to inhalation must be considered for the dose assessment of construction workers who will be deployed at the Chernobyl site to reconstruct the old or to build the new Shelter, in the future.     

Organic forms of artificial radionuclide compounds in soil solutions from natural biogeocenosis

The date on the distribution of the main radiologicaly important polutants of biosphera (90Sr, 137Cs, 239 + 240Pu, 238Pu, 241Am) over the molecular mass fractions of organic matter in the soil solutions of natural environments are presented. Molecular mass constitution and radionuclide content in the fractions are dependent on radionuclide nature and type of soil and change along the soil profile. The major portion of 238Pu, 239 + 240Pu and 241Am (72-98%) was bound with organic matter in the soil solutions. In the case of organic horizons, these radionuclides were selectively connected with the fractions of high molecular masses (MMw > or = 2000). Radiostrontium is present principally in the fraction of inorganic compounds (19-100%) and in the low molecular mass fraction of organic matter (MMw = 350-500). A selective interaction of 137Cs with organic matter of definite molecular masses was not observed. The radionuclide was found in the "organic" fractions of a wide range of molecular masses (MMw from 350-500 to > or = 18,000) (34-97%) as well as in the fraction of inorganic compounds. The data obtained can provide the theoretical basis for explanation of higher mobility of 90Sr in soil profiles compared to other radionuclides.     

90Sr, 137Cs, 238Pu, 239+240Pu,and 241Am radionuclides in macrophytes within the Krasnensky flood plain: species specificity of concentration and distribution in phytocenosis components

The analysis of the content of radionuclides 90Sr, 137Cs, 238Pu, 239 + 240Pu and 241Am in water vegetation of flood plain reservoirs has allowed studing features of radionuclide accumulation by various species of macrophytes and revealing bioindicators of radionuclide contamination. Thus species-specificity of radionuclide accumulation can essentially change the contribution of different species to a percentage ratio of the radionuclide content in phytomass of reservoirs in comparison with fund of higher aquatic plants.     

The distribution of the radionuclides in the main components of lake ecosystems within the Chernobyl NPP exclusion zone

The results of the studies devoted to the distribution of radionuclides 90Sr, 137Cs, 238Pu, 239 + 240Pu and 241Am in 1998-2003 in main components of Glubokoe Lake and Dalekoe-1 Lake located within Krasnensky flood lands of the Pripyat River (inner exclusion zone of the Chernobyl NPP) were analysed. The data about the radionuclide content in bottom sediments, in water, in seston, in macrozoobenthos (including bivalvia molluscs), in gasteropods molluscs, in higher aquatic plants and in fish are presented.     

Quantitative evaluation of 90Sr, 137Cs, 239Pu, 241Am transfer from polluted soil to gastric and intestine juice of cows

Quantitative parameters of 90Sr, 137Cs, 239Pu and 241Am transfer from solid phase of soil to gastric, intestine juice of cows as well as to imitating solutions have been estimated on the base of results of laboratory incubation experiments. A prevailing role of enzyme complex and microflora of gastrointestinal tract in radionuclides transfer from solid phase of soil to solution has been shown.     

Radiobiological effects on plants and animals within Semipalatinsk Test Site (Kazakhstan)

The Semipalatinsk Test Site (STS) was the main place of nuclear devices tests in the former Soviet Union. From 1949 to 1989 about 460 nuclear explosions have been carried out at STS. Radioactive contamination of STS territory has the extremely non-uniform character. The main dose-forming radionuclides are 137Cs, 90Sr, 152Eu, as well as 154Eu, 60CO, 239,240Pu and 241Am. The greatest specific activity of 137Cs and 239,240Pu in ground are n x 10(3) kBk/kg, 152Eu - 96 kBk/kg, 154Eu - 10.4 kBk/kg, 60Co - 20.5 kBk/kg, 241Am - 15 kBk/kg. However, up to now, within STS sites exists where gamma-dose rate comes to 60 microGy/h, that is enough for induction reliable biological effects in animals and plants. Inhabiting territory of STS plants and animals are characterized by increased level of mutagenesis, changes of morpho-anatomic indices and parameters of peripheral blood, by the increase of asymmetry bilateral indices, change of composition and structure of communities.     

Association of Chernobyl-derived 239+240Pu, 241Am, 90Sr and 137Cs with different molecular size fractions of organic matter in the soil solution of two grassland soils

Radiocesium is normally bound only rather weakly and unspecifically by humic substances, in contrast to the actinides Pu and Am. Recently, however, it was observed that fallout ¹³⁷Cs in the soil solution from an Of-horizon of a podzol forest soil (slightly decomposed plant material) was associated essentially only with one single size fraction of the humic substances. In deeper soil layers with well humified material (AOh-horizon), radiocesium was associated with all size fractions of the dissolved organic matter (DOM). To examine whether this unexpected behaviour is also observable for DOM isolated from other soils, we determined the association of fallout ¹³⁷Cs,⁹⁰Sr,²³⁸Pu, ^239+240Pu and ²⁴¹Am with various size fractions of DOM from in situ soil solutions isolated from two layers (0–2 cm and 2–5 cm) of two grassland soils (a soddy podzolic soil and a peat soil) within the 10 km zone of the nuclear reactor at Chernobyl (Ukraine). The four size fractions of DOM as obtained by gel filtration of the soil solution were (mean nominal molecular weight in daltons): fraction I: ≥2000, fraction II: 1300; fraction III: 560, fraction IV: inorganic compounds. The results for the well humified DOM (humus accumulation horizon of podzol, deeper layer of peat soil) showed that Pu and Am are essentially associated with the high molecular weight fractions, while Sr is present only in the `inorganic' fraction. Radiocesium is found in all the size fractions separated. A quite similar pattern was also found for Pu, Am, and Sr in the soil solution from only slightly decomposed plant material (0–2 cm of peat soil), but not for radiocesium. This radionuclide was again essentially only observable in one single low molecular weight fraction of DOM. The above results thus support our recent observations in the different horizons of a forest podzol mentioned above, even though no reason for the different binding of radiocesium by well humified soil organic matter and by only slightly decomposed plant material can be given at present. The data demonstrate, however, that information on only the total amount of a radionuclide in the soil solution will not be sufficient to interpret or predict its fate adequately in the soil. Received: 13 February 1998 / Accepted in revised form: 14 July 1998     

Environmental radioactivity in the South Urals 1990-1997. An international study supported by INTAS, EC and national funding

Radioecological studies carried out in a joint co-operation between Russian, Ukrainian and Danish Laboratories are reported. The environmental impact of routine, discharges as well as accidental events, notably the Kyshtym accident in 1957 and the Karachay wind dispersion in 1968 have been studied. From measurements and based on model assumptions it has been estimated that the Ob river system outside Mayak, i.e. first of all the Techa and Iset rivers and their floodplains contain 0.1 PBq 90Sr, 0.3 PBq 137Cs and 0.8 TBq 239, 240Pu. The uncertainty of these estimates is a factor of 3-4. The present contamination from the Kyshtym accident outside the Mayak area is calculated to 0.1-0.5 PBq 90Sr and from the Karachay incident the contamination is 0.05-0.1 Bq 137Cs. The environmental contaminations with Pu from these two events are in the order of 1 TBq. The occurrence of 99Tc, 129I and 237Np in highly contaminated Techa river sediments collected outside Mayak is for the first time reported.     

Bioavailability of 239+240Pu and 137Cs in aerosols and deposited dusts: a comparative study by fractional extraction

The bioavailability of ¹³⁷Cs and ^239+240Pu in soil, dust and aerosols has been determined by applying a fractional extraction procedure. In aerosols, 47–57% of ¹³⁷Cs was found to be easily exchangeable. This differs significantly from soil and deposited dust samples collected on a nearby street as well as on grassland where ¹³⁷Cs was quantitatively found in the acid-soluble fraction and the residue. A similar difference was observed for ^239+240Pu: 47% of ^239+240Pu in aerosols was associated with the organic fraction, while in soil and deposited dust from grassland 63–75% of ^239+240Pu was found in the acid-soluble fraction. In deposited street dust, 53% of ^239+240Pu was associated with the oxide fraction.     

241Am dating of lake sediments

²⁴¹Am derived from decay of fallout ²⁴¹Pu is now frequently detected in analyses of lake sediments by low-background gamma assay, and offers an alternative to weapons test ¹³⁷Cs in dating recent sediments at those sites where the ¹³⁷Cs record has been degraded by post-depositional mobility or obliterated by Chernobyl fallout. Calculations of the in-growth of ²⁴¹Am from ²⁴¹Pu indicate a nominal distribution broadly similar to that of ¹³⁷Cs, with the maximum ²⁴¹Am activity occuring in fallout dating from 1963. Results from a number of sites suggest that ²⁴¹Am is significantly less mobile in lake sediments than ¹³⁷Cs, and that its distribution in cores reflects more closely the fallout record. Since further decay of existing weapons debris will increase ²⁴¹Am concentrations by about 24% over the next 40 years, ²⁴¹Am is likely to play an increasingly important role in assessing the validity of ²¹⁰Pb dates at sites with varying sediment accumulation rates.     

Long-term development of the radionuclide exposure of murine rodent populations in Belarus after the Chernobyl accident

As a determinant of the associated health risks, the behavior of radionuclides in natural ecosystems needs to be better understood. Therefore, the activity concentration of various long-lived radionuclides released due to the Chernobyl accident, and the corresponding contributions to the whole-body dose rate, was studied as a function of time in mammalian indicator species inhabiting the natural forest ecosystems of Belarus, the bank vole (Clethrionomys glareolus) and the yellow-necked mouse (Apodemus flavicollus). The activity concentrations of ¹³⁷Cs, ¹³⁴Cs, ⁹⁰Sr, ²³⁸Pu, ^239,240Pu, ²⁴¹Pu and ²⁴¹Am in soil and in animals were measured at five monitoring sites with different ground deposition of radionuclides at different distances from the destroyed reactor. The observed temporal pattern of the radionuclide activity concentration in the studied animal populations reflects the changes in biological availability of these isotopes for biota, mostly due to fuel particle destruction and appearance of dissolved and exchangeable forms of radionuclides. The time course of ^134+137Cs activity concentrations in animal populations appeared as a sequence of increase, peak and decrease. Maximal levels of radiocesium occurred 1–2 years after deposition, followed by an exponential decrease. Concentrations of incorporated ⁹⁰Sr increased up to the tenth year after deposition. The activity concentrations of transuranic elements (²³⁸Pu, ^239,240Pu, ²⁴¹Pu and ²⁴¹Am) were much lower than those of the other radionuclides, in the studied animals. A considerable activity of ²⁴¹Am in animals from areas with high levels of contamination was firstly detected 5 years after deposition, it increased up to the tenth year and is expected to increase further in the future. Maximal values of the whole-body absorbed dose rates occurred during the year of deposition, followed by a decrease in the subsequent period. Generally, this decrease was monotonic, mainly determined by the decrease of the external γ-ray dose rate, but there were exceptions due to the delayed maximum of internal exposure. The inter-individual distributions of radionuclide concentrations and lifetime whole-body absorbed doses were asymmetric and close to log-normal, including concentrations and doses considerably higher than the population mean values.     

Dynamic study of the cytogenetic effects in blood lymphocytes from humans living in the Chernobyl Atomic Energy Station exclusion zone without permission

The cytogenetic examination of a group of people, self-residing in ChNPP Exclusion Zone with soil contamination density 137Cs 74-477 kBq/m2, 90Sr 33-289 kBq/m2, 238, 239 + 240Pu 1.5-10.0 kBq/m2, was conducted in 1998-1999 and also 2001. It is shown, that after 12-15 years of the accident the level of chromosome damages in Zone self-residents' lymphocytes detected by a routine analysis is higher then at the residents of control Yagotin district, Kiev region and comes to a plateau. Lymphocytes with multiple chromosome damages are detected. The probability of its transuranium elements induction which are present in the Zone is discussed at present.     

Radionuclide transfer to marine biota species: review of Russian language studies

An extensive programme of experiments on transfer of radionuclides to aquatic species was conducted in the former USSR starting from the early 1950s. Only a few of these studies were made available in the English language literature or taken into account in international reviews of radionuclide behaviour in marine ecosystems. Therefore, an overview of original information on radionuclide transfer to marine biota species available from Russian language literature sources is presented here. The concentration ratio (CR) values for many radionuclides and for marine species such as: ²³⁹Pu, ¹⁰⁶Ru and ⁹⁵Zr (crustacean), ⁵⁴Mn, ⁹⁰Sr, ⁹⁵Nb, ¹⁰⁶Ru, ¹³⁷Cs ²³⁹Pu, ²⁴¹Am and natural U (molluscs), and ⁵⁴Mn, ⁹⁰Sr, ¹³⁷Cs and ¹⁴⁴Ce (fish) are in good agreement with those previously published, whilst for some of them, in particular, for ³²P and ¹¹⁰Ag (crustaceans), ³⁵S (molluscs), ³²P, ³⁵S, ⁹⁵Nb, and ¹⁰⁶Ru (macroalgae) and ⁶⁰Co and ^239,240Pu (fish) the data presented here suggest that changes in the default CR reference values presented in recent marine reviews may be required. The data presented here are intended to supplement substantially the CR values being collated within the handbook on Wildlife Transfer Coefficients, coordinated under the IAEA EMRAS II programme.     

Influence of clay mineral type and organic matter content on the uptake of239Pu and241Am by plants

Summary The uptake of²³⁹Pu and²⁴¹Am from different clay mineral-organic matter-sand mixtures simulating contrasting soil types was examined in growth chamber experiments. The mixtures represented various combinations of organic matter (0, 5 and 10%), kaolinite (11 type) and montomorillonite (21 type) clay minerals, each at the levels of 5, 10 and 25%, and purified quartz sand (as filler).Results indicated a marked reduction in uptake of both²³⁹Pu and²⁴¹Am with increase in organic matter as well as clay content of the mixtures. The Pu Concentration Ratios (CRs) ranged from (2.5–7.0)×10^–3 in the case of kaolinite-organic matter mixtures, and from (0.9–5.5)×10^–3 in the case of montmorillonite-organic matter mixtures. The corresponding values of Am Concentration Ratios (CRs) obtained were (1.9–725.4)×10^–3 in the case of kaolinite-organic matter mixtures, and between (0.7–3.5)×10^–3 for the montmorillonite-organic matter mixtures.Reduction in the uptake of²⁴¹Am with increasing clay content was more pronounced in the montmorillonite clay-organic matter mixtures as compared to that in the case of kaolinite-organic matter mixtures. While similar qualitative reduction in²³⁹Pu CRs with increasing clay content was observed, the reduction was less marked than in the case of²⁴¹Am. The values for Am CRs were higher than the corresponding Pu CRs in kaolinite based mixtures whereas in the case of montmorillonite-organic matter mixtures Pu CRs exceeded the Am CRs.Increasing organic matter content and its interaction with both kaolinite and montmorillonite clay minerals were found to be equally effective in reducing the uptake of²³⁹Pu as well as²⁴¹Am by plants.     

Estimating Total Effective Dose Equivalents from Terrorist Use of Radiological Dispersion Devices

Radiological dispersion devices (RDDs), commonly called “dirty bombs,” utilize a conventional explosive to deliberately disperse non-fissile material as an aerosol. This analysis models total effective dose equivalent (Sv) at various locations down-wind from the detonation site subsequent to terrorists detonating a ²⁴¹Am, ¹³⁷Cs, ⁶⁰Co, ¹⁹²Ir, or⁹⁰Sr RDD. A source term for each isotope equaling 3.7 × 10¹³ Bq with an instantaneous release by either high explosives or low explosives at street level is assumed in order to evaluate total effective dose equivalent (TEDE) under various meteorological scenarios for intentional releases of non-fissile materials by terrorists. The inhalation pathway on average contributes most to TEDE. The inhalation pathway accounts for 96% (0.22 Sv) of the mean exposure estimate of 0.2321 Sv and occurs over an extremely short time frame (i.e., a few minutes). Ground shine, on average, contributes the second most to TEDE estimates accounting for approximately 4% (0.009 Sv) of the estimate. A cautionary note with regard to ground shine is warranted, however, because Hotspot estimates for this pathway are based on the assumption that a person is exposed for 4 days (96 hours). The TEDE for submersion (i.e., passing through the plume without inhaling particles) is negligible for the scenarios evaluated contributing less than 1% (5.2 × 10^?6 Sv) to the TEDE estimate averaged across all 140 model runs (5 nuclides × 2 rainfall scenarios × 2 explosive scenarios × 7 wind and atmospheric stability scenarios). The TEDE value for ²⁴¹Am from inhalation is much greater, on average, than the inhalation TEDE value for ⁶⁰Co, ¹³⁷Cs, ¹⁹²Ir, or ⁹⁰Sr. This underscores the potentially high risk to human health posed by exposure to ²⁴¹Am. Ground shine is the primary exposure pathway for ⁶⁰Co and ¹³⁷Cs due to the energetic and penetrating gamma rays those radionuclides emit. ¹⁹²Ir and ⁹⁰Sr have relatively low mean TEDE values for all of the pathways examined.     

Radioecological research of the Irtysh-River's and Ob-River's water, base and flood depositions

The radioecological research of Irtysh-river and Ob-river was held. The content of 137Cs in Irtysh water was compounded 0.62-1.23 Bq/m3, in Ob-- 0.24-0.27 Bq/m3, and the one of 90Sr in Irtysh-- 10-20 Bq/m3, and in Ob-- 5-10 Bq/m3, that is much lower than the permissible sanitary-hygienic norms for the population. The 137Cs stores density on Irtysh-river input lease was compounded 2.7 kBq/m2, is almost in 11 times slashed downstream and is peer 245 kBq/m2 before the Irtysh-river lockin. The 90Sr stores density also was slashed in surveyed leases with 212 down to 106 Bq/m2. Two variants of integrated stores of 137Cs and of 90Sr in flood of the Irtysh-river was held. The balance calculation of annual radionuclides sinks confirms the dominant amount of 137Cs and of 90Sr in downstream Ob-river leases acts now on the Ob's sleeve, instead of from the Irtysh-river as it was supposed earlier. The 137Cs medial annual inflow from the Ob's sleeve almost is in 2 times, and the 90Sr inflow is in 2.3 times more, than are acts from Irtysh-river sleeve.     

Self-renewal capacity of murine hemopoietic stem cells under internal contamination with239Pu and241Am

Summary The self-renewal capacity of murine pluripotent hemopoietic stem cells (CFU-S) of vertebral bone marrow was studied under conditions of short-term and long-term internal contamination with²³⁹Pu or²⁴¹Am in female mice. Measurement of the CFU-S self-renewal capacity was carried out using double transplantation assay. To evaluate the production of differentiated progeny of stem cells average erythroblast numbers/visible spleen colony and⁵⁹Fe-uptake/colony were computed. The marrow cellularity/vertebra and the number of CFU-S/vertebra were decreased and affected more by²³⁹Pu than by²⁴¹Am. The production of erythroblasts per a single CFU-S and the⁵⁹Fe-uptake/colony were reduced, similarly the numbers of secondary spleen colonies and of secondary CFU-S in primary colonies. The above changes resulting from impaired functions of surviving CFU-S were more serious with²⁴¹Am than with²³⁹Pu. The biological effects of plutonium and americium appeared independent of the phase of contamination.     

137Cs and 90Sr distribution peculiarities in soil and accumulation by pine tree wood and bark depending on edaphotops

The range of researches was made on 137Cs and 90Sr distribution regularities in pine tree plantations depending on different edaphic conditions. It is shown that total radionuclide amount in the forest litter depends on its thickness and is thought to be 10 to 70% for 137Cs and 20 to 60% for 90Sr. When soil fertility come increases from trophotop "A" to "C", 137Cs and 90Sr transfer factors for wood reduce. Soil humidity increase for each grade of trophic net results in increase of 137Cs transfer factors to wood and decrease for 90Sr. Total activity of 37Cs and 90Sr in pine wood plantation depends on plantation productivity and radionuclide transfer factors depending on different plantation conditions. In the most prevailing edaphotops pine wood accumulates 1-3% of 137Cs and 6-11% of 90Sr from total activity of radionuclides in biogeocenosis.