Prediction of vertical distribution of 137CS and 90SR in forest soils in Belarus

Title: Prediction of vertical distribution of 137CS and 90SR in forest soils in Belarus

Author: Perevolotsky A.N., Perevolotskaya T.V.

Reference: Radiation Biology. Radioecology, (Russian: “РАДИАЦИОННАЯ БИОЛОГИЯ. РАДИОЭКОЛОГИЯ“) 52(6), December 2012

ISSN: 0869-8031

DOI: 10.1134/S0869803112060082

Keywords: forecast, migration, 137Cs, 90Sr, specific activity, supply of radionuclides, distribution of radionuclides , quasi-factor, soil

Abstract: The article analyzes the distribution of 137cs and 90sr in vertical profile onto the soil of forest ecosystem, in Belorussia, in various conditions: content of moisture, composition of woody vegetation.  Describes various types of vertical migration of radionuclides under the surface of soil.

URL: http://lekarius.ru/external/paper/36946

Transfer of radiocesium from uncultivated soils to grass after the Chernobyl accident

Title: Transfer of radiocesium from uncultivated soils to grass after the Chernobyl accident

Author: Z. Pietrzak-Flis, P. Krajewski, G. Krajewska, N.R. Sunderland

Reference: Science of The Total Environment, Volume 141, Issues 1–3, 25 January 1994, Pages 147-153

DOI: http://dx.doi.org/10.1016/0048-9697(94)90024-8

Keywords: Radiocesium; Grass; Soil; Transfer factor; Chernobyl

Abstract: Transfer of radiocesium from uncultivated peat, loam and two sandy soils to grass in northeastern Poland was evaluated. Samples of grass and soil were collected from the same area of about 100 m² in the period from June 1988 to November 1991 twice a year. Grass was sampled from 1 m × 1 m squares by cutting to the plant base. Afterwards core samples of soil were taken from an area of 132.73 cm². ¹³⁴Cs, ¹³⁷Cs and ⁴⁰K were determined by gamma spectrometry. The average concentration of ¹³⁷Cs (to 10 cm depth) in the studied areas was in the range from 22.8 ± 2.5 Bq kg⁻¹ to 154.3 ± 13.7 Bq kg⁻¹. The average concentration of this radionuclide in grass varied from 6.76 ± 0.99 Bq kg⁻¹ dry weight (dry wt.) to 152.6 ± 37.4 Bq kg⁻¹ dry wt and depended upon the type of soil. The transfer of radiocesium to grass in the studied soils decreased in the following order: Sand I > peat > Sand II > loam. The results indicated that apart from soil, other parameters also influenced the transfer of radiocesium to grass. It has been found that ¹³⁴Cs from Chernobyl is more available to grass than ¹³⁷Cs from nuclear weapon tests.

URL: http://www.sciencedirect.com/science/article/pii/0048969794900248

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

Title: Chemical forms of γ-emitting radionuclides in soils adjacent to the Chernobyl NPP

Author: A.L. Kliashtorin, A.I. Shcheglov, F.A. Tikhomirov

Reference: Science of The Total Environment, Volume 164, Issue 3, 30 March 1995, Pages 177-184

DOI: http://dx.doi.org/10.1016/0048-9697(95)04464-C

Keywords: Radionuclides; Chernobyl NPP; Caesium; Soils

Abstract: 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 γ-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. Exchangable 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.

URL: http://www.sciencedirect.com/science/article/pii/004896979504464C

Changes in the forms of 137Cs and its availability for plants as dependent on properties of fallout after the Chernobyl nuclear power plant accident

Title: Changes in the forms of ¹³⁷Cs and its availability for plants as dependent on properties of fallout after the Chernobyl nuclear power plant accident

Author: N.I. Sanzharova, S.V. Fesenko, R.M. Alexakhin, V.S. Anisimov, V.K. Kuznetsov, L.G. Chernyayeva

Reference: Science of The Total Environment, Volume 154, Issue 1, 1 September 1994, Pages 9-22

DOI: http://dx.doi.org/10.1016/0048-9697(94)90609-2

Keywords: Chernobyl NPP; Radionuclide; Forms in soil; Availability; Transfer factor; Ecological half line

Abstract: The dynamics of exchangeable and acid soluble ¹³⁷Cs content in soils, as well as ¹³⁷Cs transfer factors for natural vegetation were studied for different sites within a 50-km zone around the Chernobyl nuclear power plant after the 1986 accident. Changes in ¹³⁷Cs forms in soils during the 6 years after the accidental release of radioactive substances and availability of this radionuclide to plants at that time were dependent on the character of radioactive fallout (fuel particles, aerosols of different dispersion) and soil type. Transformation of different ¹³⁷Cs species in soils with time after the accident was observed (destruction of fuel particles, ageing of ¹³⁷Cs and changes in the ¹³⁷Cs sorption strength of the soil solid phase). Behaviour of ¹³⁷Cs in the ‘near’ and ‘remote’ zones was different. The content of exchangeable ¹³⁷Cs in soils was found to have decreased after the accident. The average half-life of ¹³⁷Cs in grass stand in dry meadow in the ‘remote’ zone is 3.5 years, and in the second (slower) period after the accident, this half-life for ¹³⁷Cs will amount to about 17 years. The ¹³⁷Cs transfer factors for peaty swamped soils were 3.7–6.6 times as high as for soils of automorphous series.

URL: http://www.sciencedirect.com/science/article/pii/0048969794906092

Analysis of radiocaesium in the Lebanese soil one decade after the Chernobyl accident

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

Vertical distribution of radionuclides in soil of a grassland site in Chernobyl exclusion zone

Title: Vertical distribution of radionuclides in soil of a grassland site in Chernobyl exclusion zone

Author: Peter Bossew, Michael Gastberger, Herbert Gohla, Peter Hofer, Alexander Hubmer

Keywords: Chernobyl; Radionuclides; Vertical migration in soil

Abstract: Five soil profiles from a site about 8 km SE of the Chernobyl NPP were investigated for the vertical distribution of radionuclides. The average ¹³⁷Cs-inventory at the site is about 2.6 MBq/m² (reference date 1 May 1986). Apart from ¹³⁷Cs, the following radionuclides have been identified (their activity ratios to ¹³⁷Cs in brackets): ¹³⁴Cs (0.537), ¹²⁵Sb (0.068), ⁶⁰Co (0.0022), ¹⁵⁴Eu (0.016), ¹⁵⁵Eu (0.020), ^94gNb (9.5E-5), ^239/240Pu (0.0088), ²³⁸Pu (0.040), ⁹⁰Sr (0.30) and ²⁴¹Am (0.011). Apparent vertical migration velocities are between 0.14 and 0.26 cm/a, apparent dispersion coefficients range from 0.02 to 0.13 cm²/a. The rankings of the velocities v for different radionuclides are (Sr, Cs, Sb, Co, Pu)<AmD, the following rankings have been found: (Nb, Sr, Cs)<Am<Eu, Csp=0.1 level).

URL: http://www.sciencedirect.com/science/article/pii/S0265931X03002364

Resolving Chernobyl vs. global fallout contributions in soils from Poland using Plutonium atom ratios measured by inductively coupled plasma mass spectrometry

Keywords: Chernobyl; Contamination; Plutonium; Poland; Soils; Isotopic ratios; Inductively coupled plasma, mass spectrometry

Abstract: Plutonium in Polish forest soils and the Bór za Lasem peat bog is resolved between Chernobyl and global fallout contributions via inductively coupled plasma mass spectrometric measurements of ²⁴⁰Pu/²³⁹Pu and ²⁴¹Pu/²³⁹Pu atom ratios in previously prepared NdF₃ α spectrometric sources. Compared to global fallout, Chernobyl Pu exhibits higher abundances of ²⁴⁰Pu and ²⁴¹Pu. The ratios ²⁴⁰Pu/²³⁹Pu and ²⁴¹Pu/²³⁹Pu co-vary and range from 0.186 to 0.348 and 0.0029 to 0.0412, respectively, in forest soils (²⁴¹Pu/²³⁹Pu=0.2407×[²⁴⁰Pu/²³⁹Pu]−0.0413; r²=0.9924). Two-component mixing models are developed to ap portion ^239+240Pu and ²⁴¹Pu activities; various estimates of the percentage of Chernobyl-derived ^239+240Pu activity in forest soils range from <10% to >90% for the sample set. The ²⁴⁰Pu/²³⁹Pu–²⁴¹Pu/²³⁹Pu atom ratio mixing line extrapolates to estimate ²⁴¹Pu/²³⁹Pu and the ²⁴¹Pu/^239+240Pu activity ratio for the Chernobyl source term (0.123±0.007; 83±5; 1 May 1986). Sample ²⁴¹Pu activities, calculated using existing alpha spectrometric ^239+240Pu activities, and the ²⁴⁰Pu/²³⁹Pu and ²⁴¹Pu/²³⁹Pu atom ratios, agree relatively well with previous liquid scintillation spectrometry measurements. Chernobyl Pu is most evident in locations from northeastern Poland. The ²⁴¹Pu activities and/or the ²⁴¹Pu/²³⁹Pu atom ratios are more sensitive than ²⁴⁰Pu/²³⁹Pu or ²³⁸Pu/^239+240Pu activity ratios at detecting small Chernobyl ^239+240Pu inputs, found in southern Poland. The mass spectrometric data show that the ²⁴¹Pu activity is 40–62% Chernobyl-derived in southern Poland, and 58–96% Chernobyl in northeastern Poland. The Bór za Lasem peat bog (49.42° N, 19.75° E), located in the Orawsko-Nowotarska valley of southern Poland, consists of global fallout Pu.

URL: http://www.sciencedirect.com/science/article/pii/S0265931X03002522

Kinetics of dissolution of Chernobyl fuel particles in soil in natural conditions

Keywords: Chernobyl; Fuel particles; Dissolution kinetics; Sr-90; Mobility; Soil

Abstract: Kinetic of fuel particles dissolution under natural environmental conditions has been investigated using the data on ⁹⁰Sr speciation in soils collected from 1995 to 1997 within the Chernobyl nuclear power plant 50 km zone. The dependency of fuel particles dissolution constants on the soil acidity (pH=4–7) has been obtained on the basis of large and statistically reliable experimental data. Results show that between 2 and 21% of ⁹⁰Sr activity is associated with weathering resistant fuel particles. Therefore, these particles would not influence the radiological situation in the near future. The map of the main agrochemical characteristics and the map of the fuel particles dissolution constants have been created for the 30-km zone territory. According to the prognosis of dynamics of fuel particles dissolution in the investigated zone, a radiological situation along the fuel paths of radioactive fallout in present time reached a stable state. An increasing in absolute contents of ⁹⁰Sr mobile forms in neutral soils will be observed in the next 10–20 yr. However, the difference between the maximum level of mobile forms contents and their existing contents will not exceed 20%.

Use of 129I and 137Cs in soils for the estimation of 131I deposition in Belarus as a result of the Chernobyl accident

Keywords: Chernobyl; ¹²⁹I; ¹³¹I; ¹³⁷Cs; Soils

Abstract: Using radioactivity measurements for ¹³¹I and ¹³⁷Cs and nuclear activation analysis (NAA) or accelerator mass spectrometry (AMS) for ¹²⁹I, ratios of ¹³¹I/¹³⁷Cs and ¹²⁹I/¹³⁷Cs have been determined in soils from Belarus. We find that the pre-Chernobyl ratio of ¹²⁹I/¹³⁷Cs in Belarus is significantly larger than expected from nuclear weapons fallout. For the Chernobyl accident, our results support the hypothesis that there was relatively little fractionation of iodine and caesium during migration and deposition of the radioactive cloud. For sites having ¹³⁷Cs >300 Bq/kg, ¹²⁹I can potentially give more reliable retroactive estimates of Chernobyl ¹³¹I deposition. However, our results suggest that ¹³⁷Cs can also give reasonably good (±50%) estimates for ¹³¹I in Belarus.

URL: http://www.sciencedirect.com/science/article/pii/S0265931X01000807

Current development of the human and environmental contamination in the Bryansk-Gomel Spot after the Chernobyl accident.

Title: Current development of the human and environmental contamination in the Bryansk-Gomel Spot after the Chernobyl accident.

Author: Hille, R / Hill, P / Heinemann, K / Ramzaev, V / Barkovski, A / Konoplia, V / Neth, R

Reference: Radiation and environmental biophysics, 39 (2), p.99-109, Jun 2000

Keywords: contamination, Bryansk-Gomel, soil, food

Abstract: Up to 1991, it was assumed that after the Chernobyl accident in 1986 the time development of radioactive contamination with regard to environment, foodstuff, and man would decrease due to migration processes in the soil, radioactive decay, and protective measures. This assumption was confirmed by all measurements in the first few years after the accident. Since 1991, however, a change in this development has been observed, as many measurements show stagnation or in some cases even an increase of foodstuff and human contamination. If normalised to an average local ground contamination, only a few groups of foodstuffs (e.g., potatoes) show a slight decrease in radioactivity. In this paper, the time development of radioactive contamination in the Bryansk-Gomel Spot on the basis of measurements since 1991 is presented. The consequences for long-term dose assessment are discussed.

URL: http://link.springer.com/journal/411