Kyshtym Accident Research Articles

Cytogenetic consequences of chronic irradiation in rodent populations inhabiting the Eastern Ural Radioactive Trace zone

Chromosome instability in bone-marrow cells and 90Sr accumulation in the bone tissue are studied in rodents (Apodemus (Sylvaemus) uralensis Pall., 1811 and Apodemus agrarius Pall., 1771)* inhabiting the Eastern Ural Radioactive Trace (EURT) zone (Kyshtym radiation accident 1957) and adjacent areas of the Urals. Intensive mutagenic process in both species from impact plots (soil pollution by 90Sr, 2322–16690 kBq/m2) is found. Significant positive correlation of the frequency of aberrant cells and the concentration of 90Sr is shown. Possible causes of the lack of resistance to long-term mutagenic factors (over 100 generations in the 50 years since the accident), such as migration of animals and the specific configuration of the EURT zone (an extended narrow territory with a sharply falling gradient of radionuclide pollution), which considerably decrease the probability that certain changes will be fixed and inherited in a series of generations of rodents, are discussed.

Some radiobiological effects in higher plants growing on the territory of the East Ural Radioactive Trace

The spontaneous level of cytogenetic damage in three plant species (Achyrophorus maculatus (Scop.) L., Plantago lanceolata L., Plantago media L.) growing at the territory of East Ural radioactive trace was studied. The radiation resistance of plants from radioactive and control nonpolluted sites was determined. The effects of additional fractionated irradiation by different doses and the role of antioxidant systems in the formation of radioprotector effect were examined. It was shown that the level of mutation process in the plant populations growing at the radiation polluted sites is increased compared to the control populations from the pure territory. The additional acute gamma-irradiation of seeds collected from the polluted and pure territories showed the improved radiation resistance of the plants from the polluted territory. In the control population of A. maculatus in the versions with a one-hour interval between fractions, the radiation effect follows the additivity principle; in the same time, at a one-day interval between fractions, a highly significant radioprotective effect manifested most clearly in the experimental population is induced. For higher plants, the enhanced effectiveness of the functioning of antioxidant systems in plants growing at radiation polluted territories was first shown. Thus, the radioprotector mechanisms of low-dose chronic and preliminary irradiation are similar and one of these mechanisms is the activation of antioxidant systems in plants growing under conditions of chronic low-intensity irradiation for long periods of time.

Accumulation of 90Sr in the bone tissue of northern mole voles in the head portion of the East Ural Radioactive Trace

The accumulation of 90Sr in the bone tissue of northern mole voles (Ellobius talpinus Pallas, 1770) living under chronic exposure to 90Sr in the center of the Eastern Ural Radioactive Trace (EURT) with a 90Sr contamination density of 37 MBq/m2 or 1000 Ci/km2 has been evaluated. Northern mole voles live under-ground and are characterized by family organization of populations and an extremely weak tendency toward dispersal. While there are no sex- or age-related differences in 90Sr accumulation, sevenfold interindividual differences have been found. Hereditary (familial) determination of the variability of 90Sr accumulation has been demonstrated. The probable causes of the difference in the familial component from the results of laboratory experiments on inbred mice are considered. The age-related inversion of 90Sr accumulation previously found in other mammalian species in the EURT area has been confirmed. A possible mechanism of its formation is suggested.

The impacts of permanent irradiation on the terrestrial ecosystems of the Eastern-Ural Radioactive Trace

The complex radioecological investigations of the East-Ural Radioactive Trace were conducted. Three transects were established in EURT area: central, eastern and western. The current levels of soil contamination near the epicenter of the accident reach 30 × 10 3 kBq/m 2 for 90 Sr and 1 × 10 3 kBq/m 2 for 137 Cs. Contamination levels are reduced in accordance with a power function with increasing distance from the accident site and at a distance of more than 100km become close to background values. In the EURT impact area vegetation is a complex of synanthropic and semi-natural plant communities in various stages of degradation and restoration successions. The current state of phytocenosises on the sites of the demolished local villages is largely determined by the degree of human impact in the pre-accident period, and remediation activities. For most species the viability of their seed progeny, formed in a gradient of radioactive contamination, are either not different from background samples or reduced half a century after the accident. Mutability of seed progeny in impact coenopopulations in all studied species was high. Radioadaptation phenomenon, i.e. increased resistance to provocative irradiation is rare and unstable.

Assessment of radiation impact on Stellaria graminea cenopopulations in the zone of the Eastern Ural Radioactive Trace

The seed progeny of the little starwort (Stellaria graminea) growing in the zone of the Eastern Ural Radioactive Trace (EURT) and in background areas was studied. The radiation exposure of this species in the EURT zone was three orders of magnitude higher than in the background. Evidence was obtained for high interannual variation in seed viability and tolerance to additional acute irradiation, but no specific connection was revealed between these parameters and radioactive contamination level in plant habitats. Weather conditions are an important source of variation in seed viability, but significant influence of temperature and precipitation was revealed only for cenopopulations of the EURT. The proportion of seedlings with morphoses in samples from the EURT was found to be increased; additional irradiation facilitated the detection of latent abnormalities. A negative correlation between seedling survival rate and the content of low-molecular antioxidants in the seedlings was revealed in all test areas. The allozyme structure of starwort cenopopulation was analyzed for the first time. A directed switch of allele frequencies at loci Pgi-2 and Fdh was revealed in samples from the EURT.

Relationship between morphological disparity and taxonomic diversity in rodent communities in the zone of influence from the Eastern Ural Radioactive Trace in the Southern Urals

To test the hypothesis that morphological disparity increases while taxonomic diversity decreases in a radioactively contaminated environment, the relationship of these parameters was studied in communities (taxocenes) of rodents living in the Southern Urals in the zone of influence from the Eastern Ural Radioactive Trace (EURT) (2003–2008). Young of the year of six rodent species (98 samples) were examined in the background (control) area (0.2 Ci/km2) and in the impact area polluted with radionuclides from the EURT (750 Ci/km2). The dynamics of morphological disparity (MD), assessed with regard to average values of five exterior characters, was compared between the control and impact taxocenes. Taxonomic (taxocenotic) diversity was estimated with the Shannon index (H). Morphological disparity was found to increase significantly at low rodent abundance (in conditionally unfavorable years) and decrease at high abundance, with the value of MD in the impact taxocene being significantly higher. A negative correlation between MD and H was revealed (r = −0.70), in conformity with the above hypothesis. Discordance (difference in direction) of annual changes in the test parameters, with H increasing while MD decreases (or vice versa) was observed in unfavorable years; it can be used as an indicator of conditions unfavorable for rodent taxocenes.

Radioactive contamination as a type of soil degradation

Radioactive contamination of soils is considered as a separate type of degradation decreasing their fertility. Natural soil radioactivity is described. The main sources of technogenic radionuclides for the soil cover (global radionuclide fallout after nuclear weapons tests, the operation of nuclear facilities, radioactive waste) were shown. The phytomelioration of soils containing radionuclides was assessed. Issues were analyzed related to the remediation of agricultural soils after radiation accidents associated with the release of radionuclides into the environment: the discharge of radionuclides into the Techa River (1949–1953) and the Kyshtym (Southern Urals, 1957), Windscale (United Kingdom, 1957), and Chernobyl (Ukraine, 1986) accidents. The hazard of radioactive contamination of the soil-plant cover was assessed from two viewpoints: the anthropocentric (sanitary-hygienic) principle, when the degree of radioactive contamination of agricultural crops and the conformity of their radionuclide content to radiological standards are taken into account (maximum permissible concentrations of radionuclides), on the one hand, and the ecocentric (biospheric, environmental) approach, when the consequences of the irradiation of soil biota and living terrestrial organisms caused by radionuclides present in the soils are taken into account (conformity to the radiation standards and permissible radiation doses), on the other hand. For some technogenic radionuclides, the use of these principles for assessing the hazard of radioactive contamination of the soil was exemplified, which is of importance for determining the rehabilitation strategy of agricultural lands contaminated with radionuclides.

Intrapopulation variation in the quality of dandelion seed progeny in zones of chemical and radioactive contamination

Interfamilial variation in metal tolerance and radioresistance of seed progeny from F1 plants was studied in the dandelion from cenopopulations growing over several decades in gradients of radioactive or chemical contamination. The progeny from the impact zone of the Eastern Ural Radioactive Trace (EURT) proved to be highly viable but had latent injuries that accounted for a high sensitivity to additional techno� genic impact. In the F1 generation from the zone of chemical contamination, high seed viability was com� bined with increased tolerance to additional impact of radiation and heavy metals. No significant differences between responses to challenge with habitual and new factors were revealed in samples from either zone.

Radioactive inventories within the East-Ural radioactive state reserve on the Southern Urals

The large-scale nuclear accident took place at the production association “Mayak” in the Southern Urals in 1957. About 74 PBq of radioactive substances were released into the atmosphere, which resulted in the contamination of a vast area – East-Ural radioactive trace (EURT). The results of our study have shown that the density of contamination of 90Sr and 137Cs in the frontal part of the EURT are 6700–15000 and 200–400 kBq/m2, respectively. The total deposition for 90Sr within the East-Ural Radioactive State Reserve was 428.2 (286.4–643.4) TBq, for 137Cs – 15.1 (10.2–22.4) TBq, for 239,240Pu – 1.175 (0.623–2.242) TBq.

Radioadaptation of rodents in the zone of local radioactive contamination (Kyshtim Accident, Russia): 50 years on

Results of radioecological investigations of rodents having different ecological specialization - wood and field mice, northern red-backed voles and mole-voles to acute (laboratory experiment) and chronic (long-term inhabiting the East Ural Radioactive Trace - EURT) irradiation are summarized. These species are greatly distinguished by a way of life, a migratory activity, an average life span etc. Numerous immunological, hematological and cytogenetical disturbances were found in more radioresistant wood and field mice and northern red-backed voles inhabiting the EURT zone (density of soil pollution by 90 Sr − 18.5MBq/m 2 = 500Ci/km 2 ) as compared with the reference samples. On the contrary there were no pathological shifts in more radiosensitive mole-voles from the more radioactively contaminated site ( 90 Sr − 37MBq/m 2 = 1000Ci/km 2 ). The absorbed dozes during the life for the mole-voles from the EURT zone were significantly higher (in 30 times) than these ones for mice and voles. These data testify about the possibility of radioadaptation in a series of generations in mole-voles that developed due to their ecophysiological features and isolation of settlement in the radiocontaminated zone. Mice and voles form a flowing population and slip off the prolonged influence of a damaging factor, this circumstance prevents the development of radioadaptation.

Radiation accidents – contribution to radioecological science and ecological lessons

The development of atomic industry and nuclear power engineering was accompanied by radiation incidents and catastrophes, some of these being rather large and resulting in radioactive contamination of the environment. Among the most important radiation accidents which have affected expanded areas are: the accident in the USSR in the South Urals with the formation of the East Urals Radioactive Trace in 1957, the accident in Sellafield, the United Kingdom in 1957, and the catastrophe at the Chernobyl NPP in 1986. The resulting radioactive traces – Emergency Radioactive Zones (ERZ) – have become the test sites for large-scale long-term radioecological investigations. The unique natural peculiarities of ERZs (wide variations in the environmental conditions – soil, plant-animal life, climatic factors, etc.) considering a wide range of man-made radionuclides (primarily biologically important 90 Sr, 131 I and 137 Cs) released into the environment have made it possible to quantify the parameters of radionuclide migration via a large number of trophic chains in different natural environments (terrestrial, aquatic and other ecosystems). Information has been collected on radiation and post-radiation effects in various biota representatives in a wide range of doses and dose rates (especially at the population and ecosystem levels). Different countermeasures have been developed and applied on large territories for reducing exposure of the ERZ population and for remediation of the affected areas.

Radionuclides in terrestrial ecosystems of the zone of Kyshtym accident in the Urals

It was shown that along the Eastern Ural Radioactive Trace central axis, about 100 km in length, decrease of the 90Sr and 137Cs deposition densities in soil samples may be described as an exponential function. At the western and eastern periphery of the trace, 90Sr contents in soils approached to the background level due to global fallout. 90Sr and 137Cs concentrations in seeds of some herbaceous plants have been determined. The radionuclide concentrations and the resulting dose loads upon plant seeds showed an excess over the background level of about two or three orders of magnitude.

Analysis of rodent populations in technogenically transformed areas (with reference to Apodemus (S.) uralensis from the EURT zone)

It is shown that the response of rodent populations to acute and chronic irradiation depends on its functional structure, i.e., on specific features of animals with two alternative types of ontogenetic development. Upon acute irradiation, sexually immature young of the year (animals with the second type of ontogeny) are most radioresistant. Exposure to chronic irradiation, as in the zone of the Eastern Ural Radioactive Trace (EURT), leads to an increase in the proportion of mature young of the year (animals with the first type of ontog- eny), which are the most radiosensitive part of the population. The abundance and fecundity of mice in the impact zone are consistently higher than in the background zone, which improves the adaptive potential of the population. The role of species ecological specialization and configuration of the contaminated zone in the for- mation of migrant rodent population is emphasized. It is concluded that a high migration activity allows the pigmy wood mouse (a radiosensitive species) to avoid long-term radiation exposure. DOI: 10.1134/S1067413608040085

Long-term consequences of Hypochoeris maculata L. chronical irradiation on the East-Urals radioactive trace.

The caryological study has been carried out on Hypochoeris maculata L. plants growing on the East-Urals radioactive trace. Two Hypochoeris maculata L. populations have been observed. The experimental population grows in contaminated area. 90Sr contamination density is 55 MBq/m2, 137Cs contamination density is 2,5 MBq/m2 . The control population grows in radionuclide-free area. Both in the experimental and in the control populations the plants have been detected bearing extra B-chromosomes in their karyotype. But their frequency was higher in the experimental population than in the control one. In the experimental population the plants with main A-chromosome set caryotype changes have been met in 9 families out of 30 families observed. In the control population one such family has been detected out of 27 families observed. Two plants with karyotype changes in both chromosome sets have been detected in one family of the experimental population, which indicates sibling species appearance in the experimental population.

Windscale and Kyshtym: a double anniversary

The autumn of 2007 has seen the fiftieth anniversary of two separate events that were of great importance both for the worldwide nuclear industry and for the science of radioecology. This short article marks this anniversary by briefly reviewing the causes, releases, impacts and legacies of both the Kyshtym accident of September 1957 and the Windscale accident of October 1957.

Specific features of the allozyme structure of dandelion populations under conditions of radionuclide and chemical contamination

A study of allozyme spectra has been performed in dandelion cenopopulations growing for a long time under conditions of chemical pollution (the zone of the Nizhnii Tagil Metallurgical Plant, NTMP) or radioactive contamination (the zone of the Eastern Ural Radioactive Trace, EURT). Cenopopulations from the NTMP and EURT zones and from the background area differ significantly in the qualitative and quantitative composition of allozyme phenes. An analysis of clonal diversity has shown that all cenopopulations are phenogenetically unique. The genesis of each cenopopulation proceeded in a specific way: they had different sets of progenitor plants, whose descendants varied genetically in the course of their reproduction and more or less successful colonization of habitats, undergoing selection under the impact of natural environmental factors and technogenic stress. An increased variability of enzyme systems, compared to the sample from the background area, and, as a consequence, reduced clonal diversity may be regarded as a trait common to populations exposed to chemical or radiation stress.

Distribution of radionuclides among the main components of Lake Chervyanoe in the Eastern Ural Radioactive Trace

Radioecological conditions have been estimated in Lake Chervyanoe located on the central axis of the Eastern Ural Radioactive Trace (EURT) about 100–110 km northeast of the Mayak Production Association. Data on the 90Sr and 137Cs contents in the main components of the lake, the distribution of these radionuclides over the profile of bottom sediments, and their amounts in the lake are presented. The experimental data have been used to construct mathematical models for estimating changes in the radionuclide concentrations and amounts in the water and bottom sediments of the lake over a long period after the nuclear accident, as well as the tritium content of the lake water in different periods of time.

Pathways of adaptation of common dandelion cenopopulations to long-term chemical and radiation influences

A comparative study of the seed progeny of dandelions was performed with samples from cenopopulations growing for a long time under conditions of radioactive contamination (the zone of the Eastern Ural Radioactive Trace, EURT) or chemical pollution (the impact zone of the Nizhnii Tagil Metallurgical Plant, NTMP). The viability of seeds proved to decrease in a similar way along with an increase in technogenic pressure, irrespective of its nature. Experiments on acute exposure to heavy metals and γ-irradiation made it possible to reveal the adaptive capacities of the seed progeny from each cenopopulation. The background sample (formed beyond the zone of any impact) was relatively resistant to irradiation and very sensitive to heavy metals. The cenopopulations from the EURT and NTMP zones manifested nonspecific responses to the effects of both habitual and new factors.

Clonal diversity and rare phenes in Taraxacum officinale s.l. coenopopulations from the East-Ural radioactive trace zone

The East-Ural radioactive trace (EURT) resulting from an accident at the Mayak Production Association in 1957 is a unique region for estimating the genetic consequences of long-term exposure of natural populations to ionizing radiation. We previously used the example of Taraxacum officinale to demonstrate an increased variation in the viability and radiosensitivity of seed progeny, as well as higher frequencies of abnormal morphogenesis, chromosomal aberrations, and allozyme diversity of plant samples [10, 12]. In this study, we estimated the clonal diversity and qualitative composition of rare morphs in dandelion populations from the EURT zone. The dandelion Taraxacum officinale s.l. is a perennial herbaceous polycarpic plant from the Asteraceae Dumort family. This is an apomictic, triploid ( n = 8), polymorphic species [9]. Within the EURT, two experimental plots located on the central axis of the trail were studied. The impact plot was located in the EURT head (13 km away from the accident center); the buffer plot was located in the middle of the trail (86 km from the center). The background plot was outside the region of radionuclide pollution. Etiolated plant leaves (from at least 70 plants) were used for allozyme analysis in 6.4% polyacrylamide gel in a Tris‐EDTA‐borate system [14]. The gel was stained using the standard technique [13]. The clones, i.e., plant groups with identical multilocal allozyme phenotypes, were distinguished from the allozyme spectra of PGI (two zones of activity), 6-PGDH, FDH, EST, GDH, and GOT. Rare morphs were those represented by one to three plants per sample [3]. Detailed radioecological characteristic of the EURT zone were reported earlier [8, 10]. Note that, taking into account the natural radiation background, additional exposure of meristematic plant tissues on the buffer and impact plots exceeded the background level by factors of 4 and 240, respectively. The community was of the secondary dry herb‐grass meadow type in all plots; the soil of the gray forest type in all plots. In total, 21 clones were identified in all populations studied, most of these clones being unique (figure). In the background and buffer samples, ten and seven allozyme phenotypes were determined, which were represented by 32 (78%) and 82 (87%) plants, respectively. In the impact coenopopulation containing 18 plants (42%), six clones were identified. The only common clone (no. 2) was found in chronically irradiated conopopulations. Although this clone dominated in both plots (53.7 and 27.8% in the middle and head EURT regions, respectively), the proportions of this plant phenotype differed almost twofold in the samples. Coenopopulations of the buffer and background regions also contained a common clone (no. 1), and the corresponding proportions of plants were similar. No common allozyme phenotypes were found in the background and impact coenopopulations. Each population from the EURT zone contained five unique clones,

THE ???AQUASCOPE??? SIMPLIFIED MODEL FOR PREDICTING 89,90Sr, 131I, and 134,137Cs IN SURFACE WATERS AFTER A LARGE-SCALE RADIOACTIVE FALLOUT

Simplified dynamic models have been developed for predicting the concentrations of radiocesium, radiostrontium, and I in surface waters and freshwater fish following a large-scale radioactive fallout. The models are intended to give averaged estimates for radionuclides in water bodies and in fish for all times after a radioactive fallout event. The models are parameterized using empirical data collected for many lakes and rivers in Belarus, Russia, Ukraine, UK, Finland, Italy, The Netherlands, and Germany. These measurements span a long time period after fallout from atmospheric nuclear weapons testing and following the Chernobyl accident. The models thus developed were tested against independent measurements from the Kiev Reservoir and Chernobyl Cooling Pond (Ukraine) and the Sozh River (Belarus) after the Chernobyl accident, from Lake Uruskul (Russia), following the Kyshtym accident in 1957, and from Haweswater Reservoir (UK), following atmospheric nuclear weapons testing. The AQUASCOPE models (implemented in EXCEL spreadsheets) and model documentation are available free of charge from the corresponding author.