Ecological risks in some sites in Kaluga region contaminated with radionuclides as a result of the Chernobyl accident

The study was aimed to evaluate ecological risks in some sites in Kaluga region contaminated with radionuclides following the Chernobyl accident. Data of the "Chernobyl" data base were used for risk evaluation. Dose rates to biota and ecological risks were evaluated in accordance with recom-mendations of "Roshydromet" and ICRP (Publication 108). Density of soil contamination with radio-nuclides in May 1986 was evaluated with the use of measured data and calculated isotope ratios. The highest calculated dose rate to reference organisms was 0.19-0.46 mGy/d in the first period af-ter the accident, it was below the level of ecological safety. The main contributor to radiation dose to plants and soil invertebrates was soil radionuclides. The main contributors to dose to vertebrates were external radiation and internal exposure to incorporated radionuclides. In the first period fol-lowing the accident some vertebrates and the pine tree received the highest radiation doses. Radi-onuclides 131I, 140Ba+140La were the main contributors to dose to the reference organisms. Cesium radionuclides were main contributors to dose to vertebrates; radionuclides 140Ba+140La were main contributors to dose to plants and soil invertebrates. In May 1986 contribution of short-living radio-nuclides to dose was 30-80%. In the course of time contribution of 137Cs to dose increased. At pre-sent time in all sites contaminated in 1986 the level of radiation is lower, than the level, which en-sures preservation of favorable environment. Results presented in the article can be useful for study of dynamics of ecological risk values and for planning radioecological monitoring the sites af-fected by radiation as a result of radiological events. © 2018 National Medical Research Radiological Centre of the Ministry of Health of the Russian Federation. All rights reserved

Assessment of reference levels of radionuclides in soil in the areas of the Kaluga oblast affected by the Chernobyl accident

The paper presents values of reference levels of 137Cs, 90Sr and 239Pu in soil, adjusted to different land-use scenarios and specific characteristics of the Kaluga oblast areas, contaminated with radionuclides following the Chernobyl accident. The levels were assessed on the basis of radiation-hygienic and eco-logical criteria. According to radio-hygienic criterion the annual effective radiation dose from the radionu-clides in soil should not exceed 1 mSv/year. The reference levels meeting the criterion were calculated for the following land-use scenarios: 1 - permanent stay in the territory contaminated with radionuclides and unlimited agricultural exploitation; 2 - limited agricultural exploitation of the territory (homesteading); 3 - permanent stay in urban area; 4 - temporal stay of people in contaminated area (industrial usage); 5 - recreational land use (tourism). Values of transfer factors of the radionuclides from soil to food prod-ucts were calculated with the use of data of ecological and radiation-hygienic monitoring in the settle-ments of the Kaluga oblast and other settlements contaminated with radionuclides as a result of the acci-dents at the Chernobyl NPP and Mayak Production Association. For calculating reference levels on the basis of ecological criteria the following reference species were used: the Scots pine (Pinus sylvestris), red clover (Trifolium pratense), the earthworm (Lumbricus terrestris), the honey bee (Apis mellifera), the grass-snake (Natrix natrix), the mollard duck (Anas platyrhynchos), the elk(Alces alces). In areas of un-limited agricultural exploitation internal radiation dose from 137Cs is formed mainly due to intake of mashrooms and berries (79%), potato, milk and meat (19%), the dose from 90Sr - due to intake of milk (56%), vegetables (36%); from 239Pu - due to intake of fish, meat and milk (98%). The lowest reference levels of the radionuclides in soil should be in agricultural lands (scenario 1), the highest - in lands used for industrial purposes (scenario 4). Reference levels of soil contamination with 137Cs in urban territories (scenario 3) was 1.9 times higher than in lands for agricultural exploitation, with 90Sr - 105 times and for 239Pu - 156 times. Internal radiation dose within the town is lower than in rural territories, however, the contribution of gamma-radiation from 137Cs to the external dose remains the same. If the land is used in accordance with the scenario 5, reference levels values depend on natural food chains. In total, assessed reference levels of the radionuclides in lands for unlimited agricultural exploitation meet the criteria used in territories affected by radioactive contamination as a result of the Kyshtym disaster and the Chernobyl accident. The use of regional specific characteristics of radionuclides accumulation in farm products and natural foods for the assessment allows reducing conservatism in assessment of reference levels of radi-onuclides in soil, as compared to the assessment with the use of summarized reference values of the pa-rameters. The radiation-hygienic criterion, the basis for estimating reference levels of 137Cs, 90Sr and 239Pu in the scenario 1 is more rigid than the ecological criterion, whereas, in contrast, ecological criterion used for estimating reference levels for 90Sr and 239Pu in scenarios 3 and 4 is more rigid. It is recom-mended to use the most conservative value of the reference level that meets both radiation-hygienic and environmental requirements as a single indicator of the permissible content of radionuclides in soil, that ensuring the radiation safety of the population and the preservation of a favorable environment. © 2019 National Medical Research Radiological Centre of the Ministry of Health of the Russian Federation. All rights reserved

Ecological risks in some sites in Kaluga region contaminated with radionuclides as a result of the Chernobyl accident

The study was aimed to evaluate ecological risks in some sites in Kaluga region contaminated with radionuclides following the Chernobyl accident. Data of the "Chernobyl" data base were used for risk evaluation. Dose rates to biota and ecological risks were evaluated in accordance with recom-mendations of "Roshydromet" and ICRP (Publication 108). Density of soil contamination with radio-nuclides in May 1986 was evaluated with the use of measured data and calculated isotope ratios. The highest calculated dose rate to reference organisms was 0.19-0.46 mGy/d in the first period af-ter the accident, it was below the level of ecological safety. The main contributor to radiation dose to plants and soil invertebrates was soil radionuclides. The main contributors to dose to vertebrates were external radiation and internal exposure to incorporated radionuclides. In the first period fol-lowing the accident some vertebrates and the pine tree received the highest radiation doses. Radi-onuclides 131I, 140Ba+140La were the main contributors to dose to the reference organisms. Cesium radionuclides were main contributors to dose to vertebrates; radionuclides 140Ba+140La were main contributors to dose to plants and soil invertebrates. In May 1986 contribution of short-living radio-nuclides to dose was 30-80%. In the course of time contribution of 137Cs to dose increased. At pre-sent time in all sites contaminated in 1986 the level of radiation is lower, than the level, which en-sures preservation of favorable environment. Results presented in the article can be useful for study of dynamics of ecological risk values and for planning radioecological monitoring the sites af-fected by radiation as a result of radiological events. © 2018 National Medical Research Radiological Centre of the Ministry of Health of the Russian Federation. All rights reserved

A case study in the Chernobyl zone Part 2: Predicting radiation induced effects in biota

In this paper we use the FASSET framework to estimate absorbed dose rates for biota within the Chernobyl exclusion zone. The estimated doses are compared to observed biological effects within the Chernobyl exclusion zone and effects expected from summaries of existing knowledge and the extent of contamination. Although paucity of observations under conditions of chronic irradiation makes direct comparison difficult, the biological effects observed in the Chernobyl exclusion zone over the period considered here (1988-2003) are broadly in agreement with those which may have been expected