カテゴリー「ecology・environment」
Title: Testing of a foodchain model using Chernobyl 137Cs fallout data and considering the effect of countermeasures
Author: Zitouni Ould-Dada
Reference: Science of The Total Environment, Volume 301, Issues 1–3, 1 January 2003, Pages 225-237
DOI: http://dx.doi.org/10.1016/S0048-9697(02)00285-1
Keywords: Chernobyl; 137Cs; Foodchain; Countermeasures; SPADE; Dose assessment; Uncertainty; BIOMASS
Abstract: Chernobyl 137Cs fallout data obtained during the period 1986–1996 from the most contaminated area in Russia were used within the IAEA BIOMASS programme to test the reliability of radiological assessment models. This model-testing scenario included information and data on countermeasures that were applied in the test area after the accident. This paper presents the predictions of the terrestrial foodchain model SPADE that was used in this model-testing exercise. SPADE predictions compared reasonably well with test data except for pigs and wild berries where differences were up to a factor of 50 and 200, respectively. Estimated intake of 137Cs and ingestion dose by adult men and women living in the test area compared favourably with the test data. Overall, SPADE proved to be capable of simulating agricultural countermeasures and their effectiveness. Modelling of countermeasures was found to be a complex process with large uncertainties regarding their ‘real’ implementation and effectiveness. The lessons learned from this exercise will be valuable in making future dose assessments/reconstructions involving countermeasures with improved results.
URL: http://www.sciencedirect.com/science/article/pii/S0048969702002851
Title: Determination of 99Tc deposited on the ground within the 30-km zone around the chernobyl reactor and estimation of 99Tc released into atmosphere by the accident
Author: S. Uchida, K. Tagami, W. Rühm, E. Wirth
Reference: Chemosphere, Volume 39, Issue 15, December 1999, Pages 2757-2766
DOI: http://dx.doi.org/10.1016/S0045-6535(99)00210-6
Keywords: Technetium-99; Chernobyl accident; Forest soil; Deposition; Cesium-137; Migration
Abstract: Technetium-99 was determined in samples from the 30-km zone around the Chernobyl reactor. Concentrations of 99Tc in soil samples taken from three forest sites ranged from 1.1 to 14.1 Bq kg−1 dry weight for the organic soil layers, and from 0.13 to 0.83 Bq kg−1 dry weight for the mineral soil layers. In particular, for the organic layers, the measured 99Tc concentrations were one or two orders of magnitude higher than those due to global fallout 99Tc. The 99Tc depositions (Bq m−2), based on the sum of the depositions measured in organic and mineral layers, ranged from 130 Bq m−2 within the 10-km zone to about 20 Bq m−2 close to the border of the 30-km zone. Taking the corresponding measured 137Cs depositions into account, it was found that the activity ratio of ranged from 6 × 10−5 to 1.2 × 10−4. It was estimated that about 970 GBq of 99Tc had been released by the Chernobyl accident. This figure corresponded to 2%–3% of the total 99Tc inventory in the core.
URL: http://www.sciencedirect.com/science/article/pii/S0045653599002106
Title: Atmospheric deposition of cosmogenic 7Be and 137Cs from fallout of the Chernobyl accident
Author: C. Papastefanou, A. Ioannidou, S. Stoulos, M. Manolopoulou
Reference: Science of The Total Environment, Volume 170, Issues 1–2, 18 August 1995, Pages 151-156
DOI: http://dx.doi.org/10.1016/0048-9697(95)04608-4
Keywords: Atmospheric depositional flux; Cosmogenic radionuclides; Chernobyl accident
Abstract: Atmospheric (tropospheric) depositional fluxes of the naturally occurring 7Be of cosmogenic origin and 137Cs from fallout of the Chernobyl accident were measured over a 7-year period (January 1987–December 1993) at Thessaloniki, Greece (40° 38′N, 22° 58′E). The annual total deposition fluxes of 7Be varied between 854 Bq/m2 (1987) and 1242 Bq/m2 (1992), showing a minimum in the years 1988–1989. The annual total deposition fluxes of 137Cs varied between 183 Bq/m2 (1987) and 16.4 Bq/m2 (1992), showing a significant decrease as expected for natural removal and radioactive decay and no new releases from nuclear facilities or weapons testing. The annual average total deposition velocity for 7Be was from 0.3 cm/s (1988) up to 0.8 cm/s (1991), while for 137Cs the corresponding values were much higher, hence 137Cs was associated with larger atmospheric particles. High 7Be concentrations in air were related to the very little solar activity (1987–1988 and 1993–1994), while low 7Be concentrations in air related to the high solar activity (1989–1991). Maximum 137Cs concentrations in air were registered during the spring 1991 and 1992, reflecting some stratospheric inputs. An unusual highly elevated value of 137Cs concentration in air, reaching 0.25 mBg/m3, was observed during the summer 1990.
URL: http://www.sciencedirect.com/science/article/pii/0048969795046084
Title: Resuspension of coarse fuel hot particles in the Chernobyl area
Author: Florian Wagenpfeil, Jochen Tschiersch
Reference: Journal of Environmental Radioactivity, Volume 52, Issue 1, January 2001, Pages 5-16
DOI: http://dx.doi.org/10.1016/S0265-931X(00)00081-3
Keywords: Resuspension; Chernobyl fallout; Hot particles; Aerosol sampler; Digital autoradiography
Abstract: Measurements of resuspended aerosol in the Chernobyl 30-km exclusion zone have shown coarse fuel hot particles in the activity range 1–12 Bq per particle. The particles were sampled with newly designed rotating arm impactors which simultaneously collect during the same experiment three samples with fuel particles in the size ranges larger than 3 μm, larger than 6 μm and larger than 9 μm in geometric diameter. The radionuclide ratios, determined after γ-spectrometry, were in good agreement with the theoretical calculations for the radionuclide-composition of the Chernobyl Nuclear Power Plant at the moment of the accident and the measured hot particles in soil in the early years after the accident. The number concentrations of airborne hot particles were derived from digital autoradiography. For wind resuspension, maximal concentrations of 2.6 coarse hot particles per 1000 m3 and during agricultural activities 36 coarse hot particles per 1000 m3 were measured. The geometric diameter of single hot particles was estimated to be between 6 and 12 μm.
URL: http://www.sciencedirect.com/science/article/pii/S0265931X00000813
Title: The use of weather radar in assessing deposition of radioactivity from chernobyl across England and Wales
Author: H.M. ApSimon, K.L. Simms, C.G. Collier
Reference: Atmospheric Environment (1967), Volume 22, Issue 9, 1988, Pages 1895-1900
DOI: http://dx.doi.org/10.1016/0004-6981(88)90078-9
Keywords: Wet deposition; weather radar; Chernobyl; nuclear accidents; 137Cs
Abstract: Deposition of radionuclides from the Chernobyl accident depended critically on patterns of precipitation intercepting the material. This paper describes the use of the RAINPATCH model to calculate wet deposition of 137Cs over England and Wales. This puff-based model makes direct use of precipitation data measured by weather radar to determine the scavenging of airborne material. The detailed spatial and temporal resolution of when and where material was scavenged provides good agreement with measurements. Since all the data used could potentially have been available at the time, such methods could usefully be applied in real time in the event of any future accident releasing such radionuclides.
URL: http://www.sciencedirect.com/science/article/pii/0004698188900789
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
Title: The transfer capability of long-lived Chernobyl radionuclides from surface soil to river water in dissolved forms
Author: H Amano, T Matsunaga, S Nagao, Y Hanzawa, M Watanabe, T Ueno, Y Onuma
Reference: Organic Geochemistry, Volume 30, Issue 6, June 1999, Pages 437-442
DOI:http://dx.doi.org/10.1016/S0146-6380(99)00028-5
Keywords: Sr-90; Cs-137; Transuranic elements; Speciation; Surface soil; Runoff; Dissolved organic materials; Fulvic acid; Ultrafiltration; Chernobyl 30 km zone
Abstract: Hydrologic runoff is one of the main processes in which radionuclides deposited in the surface environment migrate widely in both particulate and dissolved forms. This paper focuses on the transfer capability of long lived Chernobyl radionuclides from surface soil to river water in dissolved forms. First, concentration and speciation of radioactive Cs, Sr and transuranic isotopes, such as Pu and Am, were examined in undisturbed surface soil along the river in the exclusion zone (30 km zone) near the Chernobyl Nuclear Power Plant (NPP) in order to validate the radioactive contamination characteristics. Almost all radioactivities exist in the very top surface in the undisturbed soil layer. Sr-90 in the soil was estimated to be highest in the water soluble and exchangeable fractions, which were easily accessible to river water as a dissolved fraction. Pu isotopes and Am-241 are major radionuclides in free humic and free fulvic acid fractions. Secondly, surface soil near the Sahan River was extracted with distilled water, as an analogue of rain water, to estimate the dissolved fraction in runoff components from surface soil to river water. After a filtration procedure, extracted water was treated with ultra filtration techniques separating the molecular weight fractions of beyond and below 10,000 Da. Each fraction was measured for the radioactivity and the characteristics of organic materials including humic substances. Most Pu and Am exist in the molecular weight fractions beyond 10,000 Da, in spite of the fact that most of the dissolved organic fractions exist below 10,000 Da. This means that transuranic elements such as Pu and Am are associated with mobile high molecular weight materials like fulvic acids in water leachates.
URL: http://www.sciencedirect.com/science/article/pii/S0146638099000285
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
Title: Application of Chernobyl-derived for the assessment of soil redistribution within a cultivated field
Author: Valentin Golosov
Reference: Soil and Tillage Research, Volume 69, Issues 1–2, February 2003, Pages 85-98
DOI: http://dx.doi.org/10.1016/S0167-1987(02)00130-7
Keywords: Chernobyl; ; Soil redistribution; Erosion; Method
Abstract: Vast areas of Europe were contaminated by the Chernobyl-derived in April–May 1986. This paper reports a detailed study of the post-fallout redistribution within a 1 ha field located in the Chasovenkov Verh catchment in the northern part of the Middle-Russian upland. Particular attention was paid to the study of reference inventories. It is shown that the random spatial variability of is similar within undisturbed and cultivated parts of a flat interfluve. Systematic spatial variability is not essential for a relatively short (200 m) topographical unit with simple relief. The analysis of a soil redistribution pattern within the study field using the Chernobyl technique demonstrates that it is possible to identify areas of soil loss/gain. This pattern does not reflect soil redistribution for the whole field, because these have been only 12 years since the Chernobyl accident. Net erosion rates based on method were comparable to soil losses directly measured at the study field.
URL: http://www.sciencedirect.com/science/article/pii/S0167198702001307
Title: Nuclear weapon and Chernobyl debris in the troposphere and lower stratosphere
Author: Ludwika Kownacka, Zbigniew Jaworowski
Reference: Science of The Total Environment, Volume 144, Issues 1–3, 29 April 1994, Pages 201-215
DOI: http://dx.doi.org/10.1016/0048-9697(94)90439-1
Keywords: Radionuclides; Troposphere; Stratosphere; Nuclear tests; Chernobyl
Abstract: High altitude aircraft sampling of aerosols has been carried out at 4–7 levels up to 15 km over Poland. From 1973 to 1991 a total of 102 vertical concentration profiles of 90Sr, 134Cs and 137Cs, and 83 profiles of 144Ce were determined. One year after the sub-megaton nuclear test in 1980, 137Cs was almost completely removed from the stratosphere. The Chernobyl debris was found in the stratosphere from the third day after the accident until the end of 1991. In May 1986 the concentration of 134Cs and 137Cs at stratospheric altitudes reached about 0.5% of that between the ground level and 3 km. Residence times of Chernobyl radiocesium in the lower stratosphere systematically increased between 1987 and 1991, in variance with those of the debris from nuclear tests. The vertical concentration profiles and the long residence times of radiocesium indicate that the non-violent meteorological processes were transporting the Chernobyl debris into the lower stratosphere, immediately and long after the accident. We postulate that the same quiescent processes transport vast amounts of resuspended particulate organics from the surface of land and sea into high altitudes, and may thus bear on the chemistry of the stratosphere.
URL: http://www.sciencedirect.com/science/article/pii/0048969794904391
