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PubMed1992

Efficiency of measures aimed at decreasing the contamination of agricultural products in areas contaminated by the Chernobyl NPP accident.

The sequence of agricultural countermeasures taken in the Polessye area of the Ukraine contaminated by radionuclides as a result of the Chernobyl NPP accident is discussed. The efficiency of these countermeasures has been analysed. The concentration of 137Cs in crops has been shown to vary 10-100-fold, depending on the biological features of the plant species and on soil properties. Liming and mineral fertilizing of meadows increase the yield of grass and reduce 137Cs transfer to cows' milk up to 3.5-fold.

Accidents↗
PubMed1992

Mathematical modeling of radionuclide dispersion in the Pripyat-Dnieper aquatic system after the Chernobyl accident.

The Chernobyl accident heavily contaminated the largest aquatic system in the Ukraine, requiring the development of a model-based decision support system in the field of aquatic radioecology. The main objectives of the system were to simulate and predict radionuclide dispersion in the Pripyat-Dnieper River-reservoir system, assess the effectiveness of special hydraulic countermeasures designed to decrease the rate of radionuclide dispersion in the water bodies, and support the Dnieper reservoirs' management operations. A hierarchy of mathematical models was developed. A two-dimensional (2-D) vertical-longitudinal model, a 2-D lateral-longitudinal model, a one-dimensional (1-D) channel model and a box-type model are briefly presented. These models describe the main features of radionuclide dispersion, including the processes governing radionuclide-sediment interactions. Examples of the models' applications are presented to show the peculiarities of radionuclide dispersion in this aquatic system.

Accidents↗
PubMed1992

The structure of Dreissena polymorpha populations from basins adjacent to the Chernobyl atomic power station.

The genetic and morphological differences among seven Dreissena polymorpha populations exposed to various environmental factors in the water basins adjacent to the Chernobyl atomic power station were examined. All of the populations showed differences in gene frequencies at four polymorphic loci. The populations could be divided into two groups according to temperature regime at the breeding site. Differences in Dreissena polymorpha populations were observed largely for those loci that showed significant deviations from the Hardy-Weinberg distribution. Radiation failed to cause any significant effect on the population structure. Within the limits considered, diversity in shell coloration among Dreissena polymorpha populations was governed by conditions at the breeding site (character of the substrate, rate of water flow, etc.), and not by thermal or radioactive contamination.

Accidents↗
PubMed1994

Main investigation results on the forest radioecology in the Kyshtym and Chernobyl accident zones.

As a result of the long-term studies of radionuclide migration in forest ecosystems in zones of radioactive contamination after the Kyshtym and Chernobyl accidents, the following trends were revealed: (1) High retention capacity of stand canopy with respect to radioactive fallout. This leads to high doses absorbed by apical and leaf meristems, beta-radiation giving the main part of the dose; (2) Fast self-decontamination of crowns during the growth period and relatively slow decontamination in the phase of physiological rest, regardless of amount of atmospheric precipitation. The rate of crown decontamination determines the value and duration of radiation stress on woody plants; (3) Accumulation not less than 95% of the total radionuclide amount in the forest litter 1-2 years after the cessation of radioactive fallout; (4) Relatively slow migration of strontium and cesium radionuclides along the forest soil profile; (5) High capacity of the forest when serving as a biogeochemical barrier to the routes of horizontal and vertical radionuclide migration and export out of the zone of initial contamination, including migration into the river water; (6) Considerable difference between strontium and cesium when migrating in forest soils and in the soil-plant system; (7) Broad variations in transfer factors for uptake of cesium-137 from soil into forest plants depending on the plant species and soil type. The primary radiobiological effects connected with irradiation of organisms are considered and secondary disturbances due to changes of ecological bonds between the components of irradiated forest ecosystem are discussed.

Cesium Radioisotopes↗
PubMed1994

Strontium-90 concentrations in human teeth in south Ukraine, 5 years after the Chernobyl accident.

Approximately 1000 human teeth, collected in South Ukraine, in 1990-1991, were measured for 90Sr concentration. The teeth were grouped into 18 samples according to the age and sex of the donors. Measured levels of 90Sr concentrations were lower by a factor of 10 than measurements taken in the mid-1960s and mid-1970s. An interesting feature of the data is a 3-fold enhancement of contamination levels in the 25-45 year-old age group of the male population. A possible explanation for this anomaly is that this age group contains a significant number of men who were mobilized immediately after the Chernobyl accident for clean-up operations within the 30-km zone around the damaged nuclear power plant.

Adolescent↗
PubMed1995

Chemical forms of gamma-emitting radionuclides in soils adjacent to the Chernobyl NPP.

Samples of sandy forest soils, meadow sandy-peat soil and meadow sandy-loam soil were taken at different sites within a 30-km zone around the Chernobyl NPP (ChNPP). The samples were extracted with water and a 0.1-N solution of ammonium acetate. The extracts were measured for gamma-radionuclides and stable cation content. The content of all mobile forms of the radionuclides present in the 0-10-cm soil layer accounts for 0.5-5% of the total radionuclide content in this layer, depending on the type of radionuclide and soil. Water soluble forms of the radionuclides were found in the 0-5-cm layer only. Exchangeable radionuclide forms were represented, as a rule, by radiocaesium in both the 0-5- and 5-10-cm layers. Content of Cs-137 exchangeable forms in the organic-mineral horizon were roughly inversely proportional to the sum of stable exchangeable cations and organic matter content. Forest vegetation takes up a significant share of the mobile forms of radiocaesium from the soils.

Cesium Radioisotopes↗
PubMed1995

Atmospheric deposition of cosmogenic 7Be and 137Cs from fallout of the Chernobyl accident.

Atmospheric (tropospheric) depositional fluxes of the naturally occurring 7Be of cosmogenic origin and 137Cs from fallout of the Chernobyl accident were measured over a 7-year period (January 1987-December 1993) at Thessaloniki, Greece (40 degrees 38' N, 22 degrees 58' E). The annual total deposition fluxes of 7Be varied between 854 Bq/m2 (1987) and 1242 Bq/m2 (1992), showing a minimum in the years 1988-89. The annual total deposition fluxes of 137Cs varied between 183 Bq/m2 (1987) and 16.4 Bq/m2 (1992), showing a significant decrease as expected for natural removal and radioactive decay and no new releases from nuclear facilities or weapons testing. The annual average total deposition velocity for 7Be was from 0.3 cm/s (1988) up to 0.8 cm/s (1991), while for 137Cs the corresponding values were much higher, hence 137Cs was associated with larger atmospheric particles. High 7Be concentrations in air were related to the very little solar activity (1987-88 and 1993-94), while low 7Be concentrations in air related to the high solar activity (1989-91). Maximum 137Cs concentrations in air were registered during the spring 1991 and 1992, reflecting some stratospheric inputs. An unusual highly elevated value of 137Cs concentration in air, reaching 0.25 mBq/m3, was observed during the summer 1990.

Air Pollutants, Radioactive↗
PubMed1995

Residual Chernobyl fallout and Sellafield pollutants found on the Isle of Man.

The Isle of Man is particularly vulnerable to radioactive pollution being located in the middle of the Irish Sea, only 55 km from the Sellafield nuclear site. Paradoxically, radioactive fallout from the accident at Chernobyl is the only significant radioactive pollution on the Island and requires legal restrictions on sheep farming. This paper gives an overview of the occurrence and magnitude of radioactive pollution on the Isle of Man, using results of live-monitoring of the Island's hill flocks since August 1987, and data selected from the results of laboratory analysis of more than 1000 samples of foodstuffs and environmental materials between 1990 and 1993. Radioactive contamination is of no significance in local agricultural produce, however, about one sixth of the Island's hill grazing land is still subject to controls. Sellafield pollutants are found only in samples from the marine environment.

Air Pollutants, Radioactive↗
PubMed1996

Transfer of radiocaesium in sensitive agricultural environments after the Chernobyl fallout in Sweden. I. County of Gavleborg.

In 1986, 15 farms in the Chernobyl-affected area of the county of Gavleborg were investigated for radiocaesium transfer to grass and cereal grain. The soil surface layer (0-5 cm) in 1986 and the crop products in 1986-1994 were analysed. The aim was to study the impact of site and soil characteristics on sensitivity of 137Cs transfer in a long-term perspective. The transfer was much higher to grass than to cereal grain. For both crop products, however, there was a considerable annual reduction. For grass, and especially in the fallout year 1986, the transfer depended on interception capacity of the stubble and grass sward, on soil fertility and K-fertilization as well as on dilution by crop growth. In the following years, the annual reduction in transfer to grass was reduced by a factor of 2 to 100. Both ploughing through the surface layer and the mixing of radiocaesium with soil contributed to a decreased transfer of radiocaesium to crops. Thick stubble and grass sward on the grassland sites was the main reason for a lag period of high persistent transfer. The annual reduction was less on organic than on mineral soils. Measures to decrease the transfer to crops are discussed in relation to a new concept to evaluate the long-term behaviour of 137Cs in agricultural environments.

Agriculture↗
PubMed1989

An increased frequency of structural chromosome aberrations in persons present in the vicinity of Chernobyl during and after the reactor accident. Is this effect caused by radiation exposure?

About a week after the reactor accident in Chernobyl, a number of German citizens returned to the Federal Republic of Germany from different places of residence in the U.S.S.R. Chromosome analyses of these individuals show a surprisingly significant increase in dicentric chromosomes in comparison to the laboratory control. Acentrics are nearly twice as frequent as dicentrics. Centric rings are also in evidence. Chromatid breaks do not significantly differ from the control with the exception of 1 place of residence. The frequency of aberrations is too high to be induced by absorbed doses calculated physically or by modelling techniques. So far, no explanation is available for the discrepancy-a factor of about 100-between calculated absorbed doses and the measured biological effect.

Accidents↗
PubMed1993

Cytogenetic study in lymphocytes from children exposed to ionizing radiation after the Chernobyl accident.

The present study concerns the monitoring of children from the Byelorussian, Ukrainian and Russian republics exposed to the fall-out of the Chernobyl accident. Cytogenetic analyses have been performed on 41 children coming from different areas and exhibiting varying amounts of 137Cs internal contamination, as evaluated by whole-body counter (WBC) analysis. On a total of 28,670 metaphases scored, radiation-induced chromosome damage is still present, although at a very low frequency. Due to the very low fraction of dicentrics, because of the time elapsed from the accident and the relatively low doses of exposure, radiobiological dosimetry is not possible for these children. However, considering that the WBC data indicate that the children are still exposed to 137Cs contamination, the observed occurrence of stable chromosome rearrangements and breaks may represent the persisting effect of continuous low doses of radiation. The present study also indicates that the parallel use of internal contamination dosimetry and cytogenetics could be usefully employed to monitor individual exposure to radiation and to define further management measures.

Accidents↗
PubMed1992

Chromosome analysis in a population living in an area of Germany with the highest fallout deposition from the Chernobyl accident.

Chromosome analyses were carried out in 1989 in peripheral lymphocytes of 30 persons from the region in southeast Bavaria (Berchtesgaden) that received the highest radiocesium deposition (> 42 kBq/m2) in Germany. These persons belonged to a group for whom body burdens of radiocesium had been surveyed in 1987. Chromosome analyses had been performed by Stephan and Oestreicher for members of the same group in the period 1987-1990, and these authors have reported elevated rates of chromosome aberrations. Pohl-Rüling et al. (1991) have, likewise, concluded that there have been increased rates of chromosome aberrations in the population of the nearby Salzburg region in 1987. In the study reported here we do not see any elevations compared to our large pre-Chernobyl control group. The difference between our findings and the report of earlier increases cannot be fully explained in terms of the known temporal decrease of the rate of dicentrics and ring chromosomes.

Accidents↗
PubMed1987

Distribution of fission products in dust samples from the region of Thessaloniki, Greece, after the Chernobyl nuclear accident.

The distribution of the fission products (95)Zr, (95)Nb, (103)Ru, (106)Ru (determined through (106)Rh), (125)Sb, (129m)Te, (134)Cs, (137)Cs, (140)Ba, (140)La, (141)Ce and (144)Ce has been determined in dust samples from the region of Thessaloniki, Greece, after the nuclear accident at Chernobyl. The samples studied also included (110m)Ag, not belonging to the products of (235)U fission. Samples showing higher concentrations of radionuclides also show a higher content in clay minerals, whereas samples having low concentrations of radionuclides usually contain large amounts of quartz and feldspars. Desorption and leaching experiments using solutions of chlorides of sodium, potassium, calcium and magnesium (0.5 N), as well as distilled and tap water, were also performed. Sodium and potassium chloride solutions were found to be efficient in desorbing and/or leaching of caesium and ruthenium isotopes to an extent of about 30%.

Journal Article↗
PubMed1989

Radiocaesium from Chernobyl in Swedish moose.

The (137)Cs activity concentrations of muscle samples taken from moose collected from the central part of Sweden were determined. Pre-Chernobyl samples had a mean (137)Cs activity concentration of 23 Bq kg(-1). Samples collected during the hunting season (mainly October) had, on average, 760 Bq kg(-1) in 1986 and 664 Bq kg(-1) in 1987. No significant differences between various muscles (neck, thigh and leg) could be seen. The correlation between ground deposition of (137)Cs and activity concentration in moose muscle was significant. There seems, however, to be other important parameters. One is the percentage of farmland within the home range of the moose-less farmland gives higher (137)Cs activity concentrations.

Journal Article↗
PubMed1990

137Cs determination and mutagenicity tests in wild Mus musculus domesticus before and after the Chernobyl accident.

Wild rodents were collected alive in a suburban area to the north of Rome before, during, 6 months and 1 year after the Chernobyl accident. Radionuclide determinations to assess their content of (137)Cs and mutagenicity tests (bone-marrow micronucleus test and sperm abnormalities assay) were performed on the captured animals. The results obtained for the species Mus musculus domesticus (which was the rodent captured in highest numbers), compared with the results obtained before the fallout, showed an increase of both micronucleated polychromatic erythrocytes (MPCEs/1000 PCEs) and (137)Cs content during and after the fallout.

Journal Article↗
PubMed1991

Legally induced abortions in Denmark after Chernobyl.

During the months following the accident in Chernobyl, Denmark experienced an increasing rate of induced abortion, especially in regions with the largest measured increase in radiation. As the increase in radiation in Denmark was so low that almost no increased risk of birth defects was expected, the public debate and anxiety among the pregnant women and their husbands "caused" more fetal deaths in Denmark than the accident. This underlines the importance of public debate, the role of the mass media and of the way in which National Health authorities participate in this debate.

Abortion, Legal↗
PubMed1991

Frequency of trisomy 21 in Germany before and after the Chernobyl accident.

For Berlin (West) the rate of trisomy 21 among newborn and all prenatally diagnosed cases can be almost completely recorded, including the maternal age distribution. During the 9-year-period from 1980 and 1988 the average number of trisomy 21 per month was about 2, following a Poisson distribution. A significant increase (P less than 0.01) was observed in January 1987, exactly 9 months after the Chernobyl accident. In a supraregional study based on greater than 30,000 prenatal diagnoses performed in 1986, no significant effect could be observed. However, the highest rates of trisomy 21 were observed in the more heavily contaminated, southern part of Germany. The majority of these fetuses were conceived during the period of greatest radioactive exposure. The data are discussed with respect to the effect of low-dose radiation around the time of conception on the induction of non-disjunction in man.

Abnormalities, Radiation-Induced↗