タグ「Technetium-99」
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: Concentration levels of technetium-99 in forest soils collected within the 30-km zone around the Chernobyl reactor
Author: S Uchida, K Tagami, E Wirth, W Rühm
Reference: Environmental Pollution, Volume 105, Issue 1, April 1999, Pages 75-77
DOI:http://dx.doi.org/10.1016/S0269-7491(98)00210-3
Keywords: Technetium-99; Chernobyl accident; Forest soil; Cesium-137; ICP-MS
Abstract: Technetium-99 (99Tc) concentrations in surface soil samples collected from three forest sites within the 30-km zone around the Chernobyl reactor were determined. A simple and rapid analytical method, which consists of volatilizing and trapping Tc in a combustion apparatus, purifying the Tc with an extraction chromatographic resin and measuring it by ICP-MS, was used for the determination. The concentrations of 99Tc in the samples ranged from 1.1 to 14.1 Bq kg−1 on an air-dried soil basis. The activities of the nuclide in the soils around the Chernobyl reactor were one or two orders of magnitude higher than in other areas which were less affected by the accident. The activity ratios of 99Tc/137Cs ratios in the soils were calculated as on the order of 3.7×10−5 to 1.3×10−4.
URL: http://www.sciencedirect.com/science/article/pii/S0269749198002103
Title: Levels and trends of radioactive contaminants in the Greenland environment
Author: Henning Dahlgaard, Mats Eriksson, Sven P. Nielsen, Hans Pauli Joensen
Reference: Science of the Total Environment. Sep2004, Vol. 331 Issue 1-3, p53-67. 15p.
DOI: http://dx.doi.org/10.1016/j.scitotenv.2004.03.023
Keywords: Caesium-137; Strontium-90; Technetium-99; Plutonium-239-240; Polonium-210; Greenland; Environmental radioactivity
Abstract: Levels of radioactive contaminants in various Greenland environments have been assessed during 1999–2001. The source of 137Cs, 90Sr and 239,240Pu in terrestrial and fresh water environments is mainly global fallout. In addition, the Chernobyl accident gave a small contribution of 137Cs. Reindeer and lamb contain the largest observed 137Cs concentrations in the terrestrial environment—up to 80 Bq kg−1 fresh weight have been observed in reindeer. Due to special environmental conditions, 137Cs is transferred to landlocked Arctic char with extremely high efficiency in South Greenland leading to concentrations up to 100 Bq kg−1 fresh weight. In these cases very long ecological half-lives are seen. Concentrations of 99Tc, 137Cs and 90Sr in seawater and in marine biota decrease in the order North-East Greenland and the coastal East Greenland current>South-West Greenland>Central West Greenland and North-West Greenland>Irmiger Sea∼Faroe Islands. The general large-scale oceanic circulation combined with European coastal discharges and previous contamination of the Arctic Ocean causes this.
URL: http://www.sciencedirect.com/science/article/pii/S0048969704002025
Title: Separation of Tc-99 in soil and plant samples collected around the Chernobyl reactor using a Tc-selective chromatographic resin and determination of the nuclide by ICP-MS
Author: Uchida, S.; Tagami, K.; Ruhm, W.; Steiner, M.; Wirth, E.
Reference: Applied Radiation and Isotopes, July-Aug. 2000, vol.53, no.1-2, pp. 69-73
DOI: http://dx.doi.org/10.1016/S0969-8043(00)00112-3
Keywords: Technetium-99; Chernobyl fallout; Organic soil; Plants of the understorey vegetation
Abstract: Technetium (Tc) is known to have high mobility in a soil–water system and also high bioavailability for plants, because the most stable form of Tc in natural surface environment is thought to be TcO−4 which is highly soluble. The chemical form of Tc, however, changes with environmental conditions. Thus, it is necessary, for realistic assessment, to obtain transfer parameters, such as transfer factors, under natural conditions. However, it is difficult to obtain these parameters using global fallout in actual fields due to its low concentration. In this study, concentrations in surface soil and plant leaf samples collected from forest sites within the 30-km zone around the Chernobyl reactor were measured for the first time. In the case of soil samples, a simple and rapid analytical method for determination of is used which consists of volatilizing and trapping Tc in a combustion apparatus, purifying the Tc with an extraction chromatographic resin, and measuring it by inductively coupled plasma mass spectrometry (ICP-MS). For plant samples, a wet digestion method in combination with the resin is applied and the is measured by ICP-MS. Concentrations of in organic soil samples and leaves of strawberry (Fragaria vesca) range from 1.1–14.8 Bq kg−1 dry weight and 0.2–6.0 Bq kg−1 dry weight, respectively. Our results indicate that soil-to-plant transfer factors for Tc are similar to those for Cs.
URL: http://www.sciencedirect.com/science/article/pii/S0969804300001123
