カテゴリー「ecology・environment」
Title: Gamma-dose rates from terrestrial and Chernobyl radionuclides inside and outside settlements in the Bryansk Region, Russia in 1996–2003
Author: Valery Ramzaev, Hidenori Yonehara, Ralf Hille, Anatoly Barkovsky, Arkady Mishine, Sarat Kumar Sahoo, Katsumi Kurotaki, Masafumi Uchiyama
Reference: Journal of Environmental Radioactivity, Volume 85, Issues 2–3, 2006, Pages 205-227
DOI: http://dx.doi.org/10.1016/j.jenvrad.2004.04.014
Keywords: Chernobyl accident; Cesium; Terrestrial radionuclides; Gamma-dose rates; Effective doses
Abstract: In order to estimate current external gamma doses to the population of the Russian territories contaminated as a result of the Chernobyl accident, absorbed gamma-dose rates in air (DR) were determined at typical urban and suburban locations. The study was performed in the western districts of the Bryansk Region within the areas of 30 settlements (28 villages and 2 towns) with the initial levels of 137Cs deposition ranging from 13 to 4340 kBq m−2. In the towns, the living areas considered were private one-story wooden and stone houses. DR values were derived from in situ measurements performed with the help of gamma-dosimeters and gamma-spectrometers as well as from the results of soil samples analysis. In the areas under study, the values of DR from terrestrial radionuclides were 25 ± 6, 24 ± 5, 50 ± 10, 32 ± 6, 54 ± 11, 24 ± 8, 20 ± 6, 25 ± 8, and 18 ± 5 nGy h−1 at locations of kitchen gardens, dirt surfaces, asphalt surfaces, wooden houses, stone houses, grasslands inside settlement, grasslands outside settlement, ploughed fields, and forests, respectively. In 1996–2001, mean normalized (per MBq m−2 of 137Cs current inventory in soil) values of DR from 137Cs were 0.41 ± 0.07, 0.26 ± 0.13, 0.15 ± 0.07, 0.10 ± 0.05, 0.05 ± 0.04, 0.48 ± 0.12, 1.04 ± 0.22, 0.37 ± 0.07, and 1.15 ± 0.19 μGy h−1 at the locations of kitchen gardens, dirt surfaces, asphalt surfaces, wooden houses, stone houses, grasslands inside settlement, grasslands outside settlement, ploughed fields, and forests, respectively. The radiometric data from this work and the values of occupancy factors determined for the Russian population by others were used for the assessments of annual effective doses to three selected groups of rural population. The normalized (per MBq m−2137Cs current ground deposition) external effective doses to adults from 137Cs ranged from 0.66 to 2.27 mSv y−1 in the years 1996–2001, in accordance with professional activities and structures of living areas. For the areas under study, the average external effective doses from 137Cs were estimated to be in the range of 0.39–1.34 mSv y−1 in 2001. The average external effective doses from natural radionuclides appeared to be lower than those from the Chernobyl fallout ranging from 0.15 to 0.27 mSv y−1.
URL: http://www.sciencedirect.com/science/article/pii/S0265931X05002171
Title: Validation of 131I ecological transfer models and thyroid dose assessments using Chernobyl fallout data from the Plavsk district, Russia
Author: I. Zvonova, P. Krajewski, V. Berkovsky, M. Ammann, C. Duffa, V. Filistovic, T. Homma, B. Kanyar, T. Nedveckaite, S.L. Simon, O. Vlasov, D. Webbe-Wood
Reference: Journal of Environmental Radioactivity, Volume 101, Issue 1, January 2010, Pages 8-15
DOI: http://dx.doi.org/10.1016/j.jenvrad.2009.08.005
Keywords: Chernobyl accident; Iodine-131; Environment modeling; Models validation; Population; Thyroid dose
Abstract: Within the project “Environmental Modelling for Radiation Safety” (EMRAS) organized by the IAEA in 2003 experimental data of 131I measurements following the Chernobyl accident in the Plavsk district of Tula region, Russia were used to validate the calculations of some radioecological transfer models. Nine models participated in the inter-comparison. Levels of 137Cs soil contamination in all the settlements and 131I/137Cs isotopic ratios in the depositions in some locations were used as the main input information. 370 measurements of 131I content in thyroid of townspeople and villagers, and 90 measurements of 131I concentration in milk were used for validation of the model predictions.A remarkable improvement in models performance comparing with previous inter-comparison exercise was demonstrated. Predictions of the various models were within a factor of three relative to the observations, discrepancies between the estimates of average doses to thyroid produced by most participant not exceeded a factor of ten.
URL: http://www.sciencedirect.com/science/article/pii/S0265931X09001751
Title: Calculations of the deposition of 137Cs from nuclear bomb tests and from the Chernobyl accident over the province of Skåne in the southern part of Sweden based on precipitation
Author: Mats Isaksson, Bengt Erlandsson, Maj-Lena Linderson
Reference: Journal of Environmental Radioactivity, Volume 49, Issue 1, May 2000, Pages 97-112
DOI: http://dx.doi.org/10.1016/S0265-931X(99)00101-0
Keywords: Deposition; Precipitation; Radiocalsium; ; Global fallout; Chernobyl fallout
Abstract: The deposition of over the province of Skåne (an area of about 100×100 km2) in the southern part of Sweden has been investigated. The origin of the deposition of is, in about equal parts, from nuclear weapons tests and from the Chernobyl nuclear accident and amounts to about 1–3 kBq/m2. The activity concentrations of and in soil samples from 16 sites distributed in a grid pattern over the investigated area have been measured and the depositions from the nuclear weapons tests and from the Chernobyl accident have been separated. These pre- and post-Chernobyl activities have been compared with depositions calculated from measurements of the activity concentrations of and in precipitation at two places and from measurements of the precipitation from a network of between 113 and 143 precipitation stations. Comparisons with in situ measurements and with aerial survey measurements have also been made. The agreement is good gain and it has been possible to gain a good and detailed knowledge in retrospect of the deposition from measurements of the deposition per mm of precipitation from just a few stations, and of the precipitation from a network of stations.
URL: http://www.sciencedirect.com/science/article/pii/S0265931X99001010
Title: Reconstruction of radioactive plume characteristics along Chernobyl’s Western Trace
Author: Ronald K. Chesser, Mikhail Bondarkov, Robert J. Baker, Jeffrey K. Wickliffe, Brenda E. Rodgers
Reference: Journal of Environmental Radioactivity, Volume 71, Issue 2, 2004, Pages 147-157
DOI: http://dx.doi.org/10.1016/S0265-931X(03)00165-6
Keywords: Chernobyl; Radioactivity; Fallout; Dispersion; Aerosol
Abstract: Using data obtained from 435 radiation sampling stations in the Red Forest, 1.5 km W of the Chernobyl Nuclear Complex, we reconstructed the deposition pathway of the first plume released by the accident, Chernobyl’s Western Trace. The dimensions and deposition rates of the plume remain sharply defined 15 years after the accident. Assuming a uniform particle distribution within the original cloud, we derived estimates of plume dimensions by applying geometric transformations to the coordinates at each sample point. Our derived estimates for the radioactive cloud accounted for 87% of the variation of radioactivity in this region. Results show a highly integrated bell-shaped cross-section of the cloud of radiation, approximately 660 m wide and 290 m high, traveling at a bearing of 264° from reactor IV. Particle sizes within Chernobyl’s Western Trace were within the most dangerous range for inhaled aerosols (2–5 μm). Therefore, reconstruction of the dispersion of such particles is critical for understanding the aftermath of nuclear and biological aerosol releases.
URL: http://www.sciencedirect.com/science/article/pii/S0265931X03001656
Title: Analysis of radiocaesium in the Lebanese soil one decade after the Chernobyl accident
Author: O. El Samad, K. Zahraman, R. Baydoun, M. Nasreddine
Reference: Journal of Environmental Radioactivity, Volume 92, Issue 2, 2007, Pages 72-79
DOI: http://dx.doi.org/10.1016/j.jenvrad.2006.09.008
Keywords: 137Cs; Activity concentration; Soil; Chernobyl accident; Lebanon
Abstract: Fallout from the Chernobyl reactor accident due to the transport of a radioactive cloud over Lebanon in the beginning of May 1986 was studied 12 years after the accident for determining the level of 137Cs concentration in soil. Gamma spectroscopy measurements were performed by using coaxial high sensitivity HPGe detectors. More than 90 soil samples were collected from points uniformly distributed throughout the land of Lebanon in order to evaluate their radioactivity. The data obtained showed a relatively high 137Cs activity per surface area contamination, up to 6545 Bq m−2 in the top soil layer 0–3 cm. The average activity of 137Cs in the top soil layer 0–3 cm in depth was 59.7 Bq kg−1 dry soil ranging from 15 to 119 Bq kg−1 dry soil. The horizontal variability was found to be about 45% between the sampling sites. The depth distribution of total 137Cs activity in soil showed an exponential decrease. Estimation of the annual effective dose due to external radiation from 137Cs contaminated soil for selected sites gave values ranging from 19.3 to 91.6 μSv y−1.
URL: http://www.sciencedirect.com/science/article/pii/S0265931X06001676
Title: Seasonal 7Be and 137Cs activities in surface air before and after the Chernobyl event
Author: A. Kulan
Reference: Journal of Environmental Radioactivity, Volume 90, Issue 2, 2006, Pages 140-150
DOI: http://dx.doi.org/10.1016/j.jenvrad.2006.06.010
Keywords: 7Be; 137Cs; Atmosphere; Aerosols; Chernobyl fallout; Nuclear weapons fallout; Sweden; Europe
Abstract: Seasonal fluctuations of cosmogenic 7Be (T1/2 = 53.4 days) and anthropogenic 137Cs (T1/2 = 30 years) activities in surface air (aerosols) have been extracted from a long data record (1972–2000) at high latitude (56°N–68°N, Sweden). Normalization to weekly average values was used to control long-term trends so that cyclical trends could be investigated. Enhanced 7Be activity was observed in spring and summer seasons and likely relates to the seasonal thinning of the tropopause. Variations in the 137Cs activity record seem to reflect how the isotope was injected in the atmosphere (stratospheric from bomb tests and tropospheric from the Chernobyl accident) and subsequent transport mechanisms. Accordingly, until 1986, the surface air 137Cs activity was strongly related to nuclear weapons test fallout and exhibits temporal fluctuations resembling the 7Be. Conversely, since 1986 the Chernobyl-produced 137Cs dominates the long-term record that shows annual cycles that are strongly controlled by atmospheric boundary layer conditions. Additionally, short-term data within the post-Chernobyl period suggest subtle intrusion of air masses rich in 137Cs that may occur throughout the year, and differences resulting from spatial occurrence at these latitudes. This is an important observation that may have to do with year-to-year variation and calls for caution when interpreting short-term data records.
URL: http://www.sciencedirect.com/science/article/pii/S0265931X06001032
Title: Fuel particles in the Chernobyl cooling pond: current state and prediction for remediation options
Author: A. Bulgakov, A. Konoplev, J. Smith, G. Laptev, O. Voitsekhovich
Reference: Journal of Environmental Radioactivity, Volume 100, Issue 4, April 2009, Pages 329-332
DOI: http://dx.doi.org/10.1016/j.jenvrad.2008.12.012
Keywords: Chernobyl; Cooling pond; Fuel particles; 90Sr; Dissolution; Remediation
Abstract: During the coming years, a management and remediation strategy for the Chernobyl cooling pond (CP) will be implemented. Remediation options include a controlled reduction in surface water level of the cooling pond and stabilisation of exposed sediments. In terrestrial soils, fuel particles deposited during the Chernobyl accident have now almost completely disintegrated. However, in the CP sediments the majority of 90Sr activity is still in the form of fuel particles. Due to the low dissolved oxygen concentration and high pH, dissolution of fuel particles in the CP sediments is significantly slower than in soils. After the planned cessation of water pumping from the Pripyat River to the Pond, significant areas of sediments will be drained and exposed to the air. This will significantly enhance the dissolution rate and, correspondingly, the mobility and bioavailability of radionuclides will increase with time. The rate of acidification of exposed bottom sediments was predicted on the basis of acidification of similar soils after liming. Using empirical equations relating the fuel particle dissolution rate to soil and sediment pH allowed prediction of fuel particle dissolution and 90Sr mobilisation for different remediation scenarios. It is shown that in exposed sediments, fuel particles will be almost completely dissolved in 15–25 years, while in parts of the cooling pond which remain flooded, fuel particle dissolution will take about a century.
URL: http://www.sciencedirect.com/science/article/pii/S0265931X08002324
Title: Remediation strategies for rural territories contaminated by the Chernobyl accident
Author: P. Jacob, S. Fesenko, S.K. Firsakova, I.A. Likhtarev, C. Schotola, R.M. Alexakhin, Y.M. Zhuchenko, L. Kovgan, N.I. Sanzharova, V. Ageyets
Reference: Journal of Environmental Radioactivity, Volume 56, Issues 1–2, 2001, Pages 51-76
DOI: http://dx.doi.org/10.1016/S0265-931X(01)00047-9
Keywords: Chernobyl accident;137Cs; Remediation; Contamination; Dose
Abstract: The objective of the present paper is to derive remediation strategies for rural settlements contaminated by the Chernobyl accident in which annual doses to a critical group still exceed 1 mSv. Extensive radioecological data have been collected for 70 contaminated settlements. A dose model based on these data resulted in estimates that are on average close to and a bit less than the official dose estimates (‘catalogue doses’) published by the responsible Ministries of Belarus, Russia and Ukraine. For eight remedial actions that can be applied on a large scale, effectiveness and costs have been assessed in light of their dependence on soil type, contamination level and on the degree of previous application of remedial actions. Remediation strategies were derived for each of the 70 settlements by choosing remedial actions with lowest costs per averted dose and with highest degree of acceptability among the farmers and local authorities until annual doses are assessed to fall below 1 mSv. The results were generalised to 11 contamination/internal-dose categories. The total numbers of rural inhabitants and privately owned cows in the three countries distributed over the categories were determined and predicted until the year 2015. Based on these data, costs and averted doses were derived for the whole affected population. The main results are (i) about 2000 Sv can be averted at relatively low costs, (ii) the emphasis on reducing external exposures should be increased, (iii) radical improvement of hay-land and meadows and application of Prussian blue to cows should be performed on a large scale if annual doses of 1 mSv are an aim to be achieved, (iv) additional remedial actions of importance are fertilising of potato fields, distribution of food monitors and restriction of mushroom consumption, and (v) for inhabitants of some settlements (in total about 8600) annual doses cannot be reduced below 1 mSv by the remedial actions considered.
URL: http://www.sciencedirect.com/science/article/pii/S0265931X01000479
Title: Important factors governing exposure of the population and countermeasure application in rural settlements of the Russian Federation in the long term after the Chernobyl accident
Author: S Fesenko, P Jacob, R Alexakhin, N.I Sanzharova, A Panov, G Fesenko, L Cecille
Reference: Journal of Environmental Radioactivity, Volume 56, Issues 1–2, 2001, Pages 77-98
DOI: http://dx.doi.org/10.1016/S0265-931X(01)00048-0
Keywords: Countermeasures; Chernobyl; Rural settlements; Remediation; Russia
Abstract: Rural settlements located in areas of the Russian Federation contaminated after the Chernobyl accident and exceeding an annual dose of 1 mSv a−1 have been classified according to 137Cs contamination density, internal dose and the neighbourhood of forests. It has been shown that, with the exception of the most contaminated areas, the internal doses decreased in accordance with a decline in 137Cs availability for plant root uptake. An inverse tendency was observed in areas with 137Cs contamination above 555 kBq m−2 which can be explained by a reduction or even termination of countermeasure application and by an increasing consumption of forest products in areas where restrictive countermeasures are still implemented. Twenty-seven settlements have been studied to estimate the effectiveness of countermeasures applied previously and to identify the most important factors governing the radiation exposure to the population and its change with time. It has been shown that the effectiveness of countermeasures which resulted in a decrease of up to 40% of doses has a tendency to decline in the long term.
URL: http://www.sciencedirect.com/science/article/pii/S0265931X01000480
Title: Geographical mapping and associated fractal analysis of the long-lived Chernobyl fallout radionuclides in Greece
Author: N.P Petropoulos, M.J Anagnostakis, E.P Hinis, S.E Simopoulos
Reference: Journal of Environmental Radioactivity, Volume 53, Issue 1, 2001, Pages 59-66
DOI: http://dx.doi.org/10.1016/S0265-931X(00)00111-9
Keywords: Chernobyl fallout; Mapping; Fractal analysis; Deposition pattern
Abstract: Immediately after the Chernobyl accident, a soil sampling programme was undertaken in order to detect and quantitatively analyse the long-lived radionuclides in the Chernobyl fallout. Soil samples (1242 in number) of 1 cm thick surface soil were collected in Greece during the period from May–November 1986. The samples were counted and analysed using Ge detector set-ups. The fallout data have already been analysed, mapped and published. In an attempt to improve this analysis and also to extend it to other fallout radionuclides, an in-house unix-based data base/geographical information system (DBGIS) was developed. Multifractal analyses of the deposition patterns have also been performed. In the present work, an analysis of the results of the deposition of [, , , , , , , , ]and are presented together with relevant fractal analysis and three characteristic contour maps. The maximum detected values of the above-mentioned radionuclides were 149.5±0.1, 76.1±0.1, 32.9±0.2, 46±2, 4.56±0.02, 7.98±0.02, 79.1±0.4, 337±2, 20.1±0.2 and 3.02±0.02 kBq m−2, respectively. Furthermore, a statistical technique to compare contour maps was introduced and applied to explain the differences which appeared in the maps of the above-mentioned radionuclides.
URL: http://www.sciencedirect.com/science/article/pii/S0265931X00001119
