To identify effects of chronic internal and external radiation exposure for components of terrestrial ecosystems, a comprehensive study of Scots pine trees in the Chernobyl Exclusion Zone was performed. The experimental plan included over 1,100 young trees (up to 20 years old) selected from areas with varying levels of radioactive contamination. These pine trees were planted after the 1986 Chernobyl Nuclear Power Plant accident mainly to prevent radionuclide resuspension and soil erosion. For each tree, the major morphological parameters and radioactive contamination values were identified. Cytological analyses were performed for selected trees representing all dose rate ranges. A specially developed dosimetric model capable of taking into account radiation from the incorporated radionuclides in the trees was developed for the apical meristem

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This article describes major studies performed by the Chernobyl Center's International Radioecology Laboratory (Slavutich, Ukraine) on radioecology of murine rodents and shrews inhabiting the Chernobyl Exclusion Zone. The article addresses the long-term (1986 -2005) and seasonal dynamics of radioactive contamination of animals, and reviews interspecies differences in radionuclide accumulations and factors affecting the radionuclide accumulations. It is shown that bioavailability of radionuclides in the "soil-to-plant" chain and a trophic specialization of animals play key roles in determining their actual contamination levels. The total absorbed dose rates in small mammals significantly reduced during the years following the Chernobyl Nuclear Power Plant accident. In 1986, the absorbed dose rate reached 1.3 -6.0 Gy hr Plant (ChNPP) accident in April 1986 presents a complex task that requires long-term observations; thereby, making the Chernobyl Exclusion Zone (ChEZ) a one-of-a-kind research site where various groups of species can be studied. Among all other species, small mammals, such as murine rodents and shrews, appear to be the most common objects of studies. They have been studied since the very first months after the ChNPP accident as a reference group; however, the primary focus of those studies was associated with biological effects. Meanwhile, the assessments of these effects only make sense relative to received doses, but, for a long time, the doses received by wild animals have not been addressed. Detailed studies on accumulation, distribution and excretion of radionuclides have been conducted for a long time, but primarily regarding agricultural and laboratory animals (Buldakov and Moskalev 1968; Aleksakhin 1982;Korneev and Sirotkin 1987;Moskalev 1989; Vandecasteele et al. 1989), and, therefore, they are not fully applicable for extrapolation to wild species. There has been very little applicable information available on wild animals inhabiting the ChEZ (Kozlo et al. 1998;Chesser et al. 2000Chesser et al. , 2001Gaychenko et al. 2001;Oleksyk et al. 2002; Ryabokon et al. 2005; Taskaev et al. 1990). In view of this, in 1998 -2010, the International Radioecology Laboratory (IRL) performed a wide range of studies on accumulation and metabolism of radionuclides, as well as on dose rates, in wild murine rodents and shrews under the actual conditions of the ChEZ. These studies were either independent studies or were conducted as part of joint international projects associated with studies of radiation impact on the genetic system of wild rodents and their laboratory analogous species (Matson et al. 2000;Baker et al. 2001; Radiation Ecology Issues Associated with Murine Rodents and Shrews in the ChEZ 3 Rodgers et al. 2001;Oleksyk et al. 2002Oleksyk et al. , 2004 Wiggins et al. 2002; Wickliffe et al. 2002). Cs distributions and assessments of parameters affecting their excretion from bodies of wild rodents can be found in earlier publications (Baryakhtar et al. 2003;Maklyuk et al. 2006. This art...

Studies on vertical migration of Chernobyl-origin radionuclides in the 5-km zone of the Chernobyl Nuclear Power Plant (ChNPP) in the area of the Red Forest experimental site were completed. Measurements were made by gamma spectrometric methods using high purity germanium (HPGe) detectors with beryllium windows. Alpha-emitting isotopes of plutonium were determined by the measurement of the x-rays from their uranium progeny. The presence of 60 Co, 134,137 Cs, 154,155

During the operational history of the Savannah River Site (SRS), many different radionuclides have been released from site facilities into the SRS environment. However, only a relatively small number of pathways, most importantly (137)Cs in fish and deer, have contributed significantly to doses and risks to the public. The "effective" half-lives (Te) of (137)Cs (which include both physical decay and environmental dispersion) in Savannah River floodplain soil and vegetation and in fish and white-tailed deer from the SRS were estimated using long-term monitoring data. For 1974-2011, the Tes of (137)Cs in Savannah River floodplain soil and vegetation were 17.0 years (95% CI = 14.2-19.9) and 13.4 years (95% CI = 10.8-16.0), respectively. These Tes were greater than in a previous study that used data collected only through 2005 as a likely result of changes in the flood regime of the Savannah River. Field analyses of (137)Cs concentrations in deer collected during yearly controlled hunts at the SRS indicated an overall Te of 15.9 years (95% CI = 12.3-19.6) for 1965-2011; however, the Te for 1990-2011 was significantly shorter (11.8 years, 95% CI = 4.8-18.8) due to an increase in the rate of (137)Cs removal. The shortest Tes were for fish in SRS streams and the Savannah River (3.5-9.0 years), where dilution and dispersal resulted in rapid (137)Cs removal. Long-term data show that Tes are significantly shorter than the physical half-life of (137)Cs in the SRS environment but that they can change over time. Therefore, it is desirable have a long period of record for calculating Tes and risky to extrapolate Tes beyond this period unless the processes governing (137)Cs removal are clearly understood.