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

Abstract

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 gamma-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.

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

“…Therefore, the opinion concerning isolation of radiogenic groups of mice and voles in the Eastern Urals radiocontaminated Reserve is erroneous. Our results are supported by data [18] about significantly lower activity concentrations of 137 Cs and 134 Cs in yellow-necked mice (Apodemus flavicollus Melchior, 1834) than bank voles (Clethrionomys glareolus Shreber, 1780) in Belarus after the Chernobyl Accident. It was also established that in the EURT zone absorbed doses, which have been accumulated in molevoles in the course both the pre-reproductive period of life and for the whole life span were significantly higher (up to 30 times) than in mice (table 1).…”

10. Chernobyl's Radioactive Impact on Fauna

“…The level of radionuclides maintained in an animal's body depends on the transfer ratio (TR, transition coefficient) and the coefficient Ryabokon' et al, 2005 * 187,000 Wild swine (Sus scrofa) Russia Pel'gunov et al, 2006 74,750 Roe deer (Capreolus capreolus) Russia Pel'gunov et al, 2006 48,355 Common shrew (Sorex araneus) Russia Ushakov et al, 1996 42,000 Little shrew (Sorex minutus) Russia Ushakov et al, 1996 24,630 Yellow neck mouse Russia Ushakov et al, 1996 (Apodemus flavicollis) 7,500 Brown hare (Lepus europaeus) Russia Pel'gunov et al, 2006 3,320 Moose (Alces alces) Russia Pel'gunov et al, 2006 1,954 White tailed deer Finland Rantavaara, 1987 1,888 Arctic hare (Lepus timidus) Finland Rantavaara et al, 1987 1,610 Moose (Alces alces) Finland Rantavaara et al, 1987 760 1 Moose (Alces alces) Sweden Johanson and Bergström, 1989 720 Reindeer (Rangifer tarandus) Finland Rissanen et al, 1987 Cs-134 60,000 Bank vole (Clethrionomys glareolus) Belarus Ryabokon' et al, 2005 * …”

“…Indicator species such as the bank vole (Clethrionomys glareolus) and the yellow-necked mouse (Apodemus flavicollus) that inhabit the natural forest ecosystems of Belarus showed maximum levels of Cs-134 and Cs-137 for 1 to (Ryabokon' et al, 2005).…”

25 years after the accident at the Chernobyl nuclear power plant: Radioecological lessons

“…Levels of contamination and dose rate estimates reported [15,16] would be expected to confer considerable insult to genetic material by ionizing radiation. Whether the observed levels of genetic anomalies in plants and animals inhabiting areas affected by Chernobyl accident have any detrimental biological significance to populations is still not known [17].…”