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Ishimori K.-I.,Japan Atomic Energy Agency | Kameo Y.,Japan Atomic Energy Agency | Matsue H.,Japan Atomic Energy Agency | Ohki Y.,Japan Chemical Analysis Center | And 2 more authors.
Applied Radiation and Isotopes | Year: 2011

In order to establish a simple and rapid analytical method for 14C in solidified products made from non-metallic low-level radioactive solid wastes such as concrete, mortar and glass by melting treatment, a radiochemical analysis in combination with alkaline fusion as a sample decomposition method was examined. A simulated solidified product containing 14C, which was prepared by using nuclear reaction 14N(n, p)14C with thermal neutron irradiation, was analyzed by the present method to compare with a conventional radiochemical analysis using oxidizing combustion. The reproducible and quantitative recovery of 14C from the simulated solidified product indicates that the present method is more efficient for 14C analysis in solidified products than the conventional method using oxidizing combustion. © 2010 Elsevier Ltd.

Fujiyoshi R.,Hokkaido University | Amano H.,Japan Chemical Analysis Center | Sakuta Y.,Hokkaido University | Okamoto K.,Hokkaido University | And 3 more authors.
Environmental Earth Sciences | Year: 2012

Carbon sources were estimated by measuring carbon isotope ratios (δ 13C and Δ 14C) with accelerator mass spectrometry (AMS) in forest soils of different lithology. Six locations were selected in temperate deciduous and coniferous stands in Slovenia (Žirovski vrh, Idrija, Kočevski Rog, Pohorje, Gorišnica, and Rakitna), where carbonate rocks consisting of limestone and dolomite are abundant as underlying bedrock. Carbon isotope fractionation would not have occurred in two carbonaceous soils, since the values of both δ 13C and Δ 14C changed consistently in these soils after thermal (550°C, 2 h) or chemical (1 M HCl, 24 h) treatments. Organic components were found to be predominant carbon sources (70-100%) in the uppermost portions (0-2 cm in depth). In deeper portions at a depth of about 30-35 cm, soil carbon may be derived completely from underlying carbonate minerals in Idria, western part of Slovenia. The Combination of heat and chemical treatments with AMS provides practical information on soil carbon sources in carbonaceous soils. © 2011 Springer-Verlag.

Kushita K.N.,Japan Atomic Energy Agency | Atarashi-Andoh M.,Japan Atomic Energy Agency | Amano H.,Japan Chemical Analysis Center
Bunseki Kagaku | Year: 2014

Gold is useful not only for traditional, ordinary human applications as ornaments, coins or electric devices, but also for nuclear and radiation applications. Here we report a study of activated gold for estimating the neutron dose in the environment in the case of the JCO criticality accident that occurred in Tokai, Japan, in 1999. We collected and analyzed 16 gold samples, such as rings, coins or necklaces stored at residents’ houses located in the range of 168 to 568 m from the accident site of the JCO. They indicated activities of gold from 91.9 to 0.322 Bq g−1 as standardized values at 06: 15 on October 1, 1999, when the criticality reaction had ceased after 20 hours of continuation. The induced radioactivity of gold samples showed a good correlation as a power function of distance. The induced radioactivity of gold is discussed with the reference data in order to estimate dose equivalent in the environment around the JCO. This paper gives an example showing the usefulness of gold in the field of nuclear and radiation studies and applications. © 2014, The Japan Society for Analytical Chemistry.

Tanaka T.,Japan Atomic Energy Agency | Otosaka S.,Japan Atomic Energy Agency | Wakita M.,Japan Agency for Marine - Earth Science and Technology | Amano H.,Japan Chemical Analysis Center | Togawa O.,Japan Atomic Energy Agency
Nuclear Instruments and Methods in Physics Research, Section B: Beam Interactions with Materials and Atoms | Year: 2010

Radiocarbon in dissolved organic matter in seawater gives information on the dynamics and origin of the dissolved organic matter. Here, we present the vertical profile of Δ14C of dissolved organic carbon in the western North Pacific Ocean. The profile was almost parallel to that for Δ14C of dissolved inorganic carbon, indicating that the time scale of seawater circulation was the main influence on the Δ14C signature of dissolved organic carbon. On the basis of the Δ14C differences between dissolved organic carbon and dissolved inorganic carbon, and a comparison with Δ14C of dissolved organic carbon in the central North Pacific Ocean, we suggest that there may be a source of younger dissolved organic carbon in the western North Pacific Ocean. © 2009 Elsevier B.V. All rights reserved.

Krajnc B.,Jozef Stefan International Postgraduate School | Fujiyoshi R.,Hokkaido University | Vaupotic J.,Jozef Stefan International Postgraduate School | Vaupotic J.,Jozef Stefan Institute | And 5 more authors.
Environmental Earth Sciences | Year: 2016

Global carbon estimates have identified abiotic CO2 as a potentially significant source of atmospheric CO2, albeit little is known about its origin. The aim of this study was to identify the origin of soil CO2 using carbon isotopes and 222Rn data. The study involved collecting data from seven Slovenian forest soils developed over bedrock with contrasting geology where different origin of soil CO2 was expected; two sampling sites were located on soils formed above carbonate bedrock, one above metamorphic bedrock and the remainder above clastic sedimentary rocks. Analysis of soil gas including the levels of CO2, carbon isotope measurements (12C, 13C and 14C) and 222Rn activity was recorded at a soil depth of 80 cm. Isotopic analysis revealed that the CO2 was young and there was no difference in the age of soil CO2 above either carbonate or non-carbonate bedrock. The data also suggest that the 13C-enrichment in soil CO2, above carbonate bedrock was a consequence of the mixing of soil CO2 with atmospheric CO2 and/or the ventilation of subterranean CO2 from pores, fissures and cavities. The latter effect was supported by the high 222Rn concentrations observed at these sites. Based on the δ13CCO2 data, photosynthesis prevailed over microbial respiration accounting for the majority (>70 %) of total soil CO2 over non-carbonate bedrock—at least at the time of sampling. Overall, results from this study could represent useful information for global carbon cycle models used to predict the impacts of climate changes. © 2016, Springer-Verlag Berlin Heidelberg.

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