巻号一覧
46 巻 (2012)
- 6 号 p. 477-
- 5 号 p. 371-
- 4 号 p. 267-
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- 2 号 p. 77-
- 1 号 p. 1-
46 巻, 4 号
Special Issue: Fukushima Review
選択された号の論文の15件中1～15を表示しています
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MITSURU EBIHARA, NAOHIRO YOSHIDA, YOSHIO TAKAHASHI2012 年 46 巻 4 号 p. 267-270
発行日: 2012/08/20
公開日: 2013/11/08
ジャーナル フリー
電子付録PDF形式でダウンロード (50K) -
H. HABA, J. KANAYA, H. MUKAI, T. KAMBARA, M. KASE2012 年 46 巻 4 号 p. 271-278
発行日: 2012/08/20
公開日: 2013/11/08
ジャーナル フリー
電子付録Airborne radionuclides from the accident of Fukushima Dai-ichi Nuclear Power Plant (FDNPP) in 2011 were measured at the RIKEN Wako Institute, Japan, about 220 km to the southwest of FDNPP, from March 15, 2011 to March 16, 2012. Radioactivity concentrations of 140Ba, 137Cs, 136gCs, 134gCs, 133gI, 132Te, 131I, 129mTe, 110mAg, 99Mo, and 95gNb (m: metastable state; g: ground state) were determined by γ-ray spectrometry with a germanium detector. The time variations of the radioactivity concentrations and their ratios in Wako are discussed by referring to those of the ambient effective dose rate as well as the amount of rainfall. The pronounced peaks of the radioactivity concentrations were observed on March 15, 20-21, and 29-31, 2011. The highest concentrations for typical radionuclides in unit Bq m-3 were 8.8 ± 0.2 for 137Cs, 1.2 ± 0.2 for 136gCs, 8.5 ± 0.2 for 134gCs, 4.7 ± 0.3 for 133gI, 58 ± 2 for 132Te, 8.0 ± 1.2 for 129mTe, and 35 ± 1 for 131I in the sample collected in the period of March 15, 2011, 11:15-11:45 JST (Japan Standard Time). The 134gCs/137Cs radioactivity ratio was determined to be 1.0 ± 0.1 for March 11, 2011, and this value was consistent with other observations related to the FDNPP accident. The environmental radioactive contamination in Wako occurred mainly on March 21, 2011, due to the first rainfall after the accident.抄録全体を表示PDF形式でダウンロード (376K) -
TAKAHIRO WATANABE, NORIYOSHI TSUCHIYA, YASUJI OURA, MITSURU EBIHARA, C ...2012 年 46 巻 4 号 p. 279-285
発行日: 2012/08/20
公開日: 2013/11/08
ジャーナル フリーThe Tohoku earthquake and tsunami occurred off the Pacific coast of Japan in March 2011 and caused the Fukushima Dai-ichi nuclear power plant accident. To assess the distribution of artificial radionuclides in Miyagi Prefecture (northeastern Japan), we measured the activity concentrations of 110mAg, 129mTe, 134Cs, and 137Cs in surface soil samples that were collected from 60-190 km north of the power plant approximately 1 month (April 16-29, 2011) after the earthquake. Since the studied samples were obtained from depths of 0-1 cm, the activity concentrations we determined were higher than those reported by the Japanese Government, whose measurements were based on soil samples obtained from depths of 0-5 cm. We found relatively high concentrations of radionuclides in surface soils in the southern and northern parts of Miyagi Prefecture. In the south, close to the border with Fukushima Prefecture, the total activity concentrations in the period April 16-29, 2011, reached approximately 27,600 Bq/kg dry soil. Relatively high total concentrations (2600-6600 Bq/kg dry soil) were also found in the northern part of Miyagi Prefecture (north Osaki, Kurihara, and Kesen-numa), but relatively low concentrations (400-1900 Bq/kg dry soil) were found in Sendai city and other areas in central Miyagi Prefecture (Higashimatsushima, south Osaki, Ishinomaki, and Onagawa). The concentrations found are consistent with the spatial variation in radiation dose rates in the air in Miyagi Prefecture.抄録全体を表示PDF形式でダウンロード (1284K) -
TAKESHI OHNO, YASUYUKI MURAMATSU, YOSHINORI MIURA, KAZUMASA ODA, NAOYA ...2012 年 46 巻 4 号 p. 287-295
発行日: 2012/08/20
公開日: 2013/11/08
ジャーナル フリーIn order to understand the behavior of radionuclides released from the Fukushima Daiichi nuclear power plant, the depth distributions of radiocesium and radioiodine were investigated in a wheat field, a rice paddy, an orchard, and a cedar forest in Koriyama, Fukushima Prefecture. Our results demonstrate that, following the nuclear power plant disaster, more than 90% of the radionuclides were distributed in the upper 6 cm of the soil column in the wheat field and within 4 cm of the surface in the rice paddy, orchard, and cedar forest. According to the measurement of radionuclides in the three adjacent agricultural fields, the variation of deposition densities in the wheat field was smaller than that of the orchard and rice paddy, suggesting that the low permeability of the orchard and paddy soils may cause horizontal migration of radionuclides during the initial deposition. This result indicates that the deposition densities in the wheat field should be appropriate for estimating the amount of fallout in the area. The deposition densities of 134Cs, 137Cs, and 131I in this area were estimated to be 512 ± 76 (SD, n = 5), 522 ± 80 (SD, n = 5), and 608 ± 79 (SD, n = 5) kBq/m2 (decay corrected to April 1, 2011), respectively. A comparison of the deposition density between the wheat field and the cedar forest suggests that more than half of the radionuclides are distributed in the tree canopies of the evergreen forestland.抄録全体を表示PDF形式でダウンロード (113K) -
HAIBO QIN, YUKA YOKOYAMA, QIAOHUI FAN, HOKUTO IWATANI, KAZUYA TANAKA, ...2012 年 46 巻 4 号 p. 297-302
発行日: 2012/08/20
公開日: 2013/11/08
ジャーナル フリーPrevious studies have shown that radiocesium (mainly 137Cs) was retained at the very surface of soils in Fukushima Prefecture. Clay minerals and micas are assumed as the main sorbents for cesium (Cs) in Fukushima, but direct evidence is lacking for this hypothesis. In this study, radiocesium in the natural sample (soil and sediment) from Fukushima Prefecture was investigated through sequential extraction experiment (modified BCR method), which showed that more than 94% of 137Cs was fixed in the residual phase. The results indicated that most of Cs occurred in the interlayer of phyllosilicate minerals. Furthermore, Cs LIII-edge extended X-ray absorption fine structure (EXAFS) showed that the Cs species adsorbed on the natural samples were very similar to those adsorbed on clay minerals and micas. This finding provided the direct evidence on the significant contribution of clay minerals or micas to Cs retention in soils from Fukushima Prefecture.抄録全体を表示PDF形式でダウンロード (169K) -
YASUJI OURA, MITSURU EBIHARA2012 年 46 巻 4 号 p. 303-309
発行日: 2012/08/20
公開日: 2013/11/08
ジャーナル フリーRadioactivity concentrations of 131I, 134Cs and 137Cs were determined for the river water sampled from the Edogawa River, the Arakawa River and the Tamagawa River, three major rivers spreading in or surrounding Tokyo Metropolis. Data from March 28 to April 7 are presented. Among the three radioactive nuclides, 131I recorded the highest radioactivity concentrations of 31 Bq/L and 11 Bq/L in water samples collected on March 28 from the Edogawa and the Arakawa Rivers, respectively. Two trends of the 131I concentration change occur from March 28 to April 7 for the Edogawa River water; the 131I concentration decreased abruptly from March 28 to March 30 and then decreased gradually until April 7. These trends suggest that 131I in the Edogawa River in late March primarily originated from fallout in the Tokyo-Chiba area, which dropped to the ground together with rain from March 21 to 24. The 137Cs concentration in river water from the Edogawa River changed differently from the 131I concentration. The highest 137Cs concentration was measured for the sample collected on March 31. Apparently, fractionation between 131I and 137Cs occurred during the transportation from FDNPP to the metropolitan area and also during the transportation from the ground where radionuclides deposited to the sampling site of river water.抄録全体を表示PDF形式でダウンロード (468K) -
MUTSUO INOUE, HISAKI KOFUJI, SEIYA NAGAO, MASAYOSHI YAMAMOTO, YASUNORI ...2012 年 46 巻 4 号 p. 311-320
発行日: 2012/08/20
公開日: 2013/11/08
ジャーナル フリーA total of 150 surface seawater samples were collected from around the Japanese Archipelago between July 2009 and February 2012, with sample collection peaking in July and October 2011. Low-background measurements revealed that, except for coastal and offshore areas around western Japan, 134Cs and 137Cs concentrations in surface waters were significantly higher than those recorded before the Fukushima Dai-ichi Nuclear Power Plant (FDNPP) accident, although their concentration levels were generally very low (<~0.1 to 1 mBq/L for 134Cs). In June 2011, concentration peaks of 1 mBq/L for 134Cs and 2.5 mBq/L for 137Cs were recorded in the Tsugaru Strait and off western Hokkaido, toward the Japan Sea approximately 150-300 km north of the high-deposition area of Akita in northern Honshu. In October 2011, 134Cs was detected only in the surface waters off western Hokkaido at a concentration of 0.2 mBq/L, which is markedly lower than the values observed in June 2011. These findings indicate that the observed radionuclide distributions could primarily be attributed to the atmospheric deposition of radionuclides emitted from the FDNPP and transported by ocean currents.抄録全体を表示PDF形式でダウンロード (889K) -
MICHIO AOYAMA, DAISUKE TSUMUNE, MITSUO UEMATSU, FUMIYOSHI KONDO, YASUN ...2012 年 46 巻 4 号 p. 321-325
発行日: 2012/08/20
公開日: 2013/11/08
ジャーナル フリーWe present our April to December 2011 observations of 134Cs and 137Cs activities in surface water at Hasaki, a coastal station 180 km south of the Fukushima Dai-ichi Nuclear Power Plant (FNPP1) accident site. We also investigate trends by using published data from several other coastal stations, including the accident site. The maximum in radiocaesium activity at Hasaki was observed in June 2011, representing a delay of two months from the corresponding maximum in April 2011 at FNPP1. Directly discharged 134Cs and 137Cs were transported dominantly southward along the coastline of northeastern Honshu, at least in May and June 2011. The reasons for the two-month delay at Hasaki are not yet clear, but clockwise current associated with a warm water eddy of which center located at 36.5 N, 141.4 E off Iwaki between Onahama and Hasaki in mid of May 2011 might prevent southward transport of 134Cs and 137Cs released from FNPP1 to Hasaki until the end of May 2011.抄録全体を表示PDF形式でダウンロード (470K) -
YASUTO MIYAKE, HIROYUKI MATSUZAKI, TAKESHI FUJIWARA, TAKUMI SAITO, TAK ...2012 年 46 巻 4 号 p. 327-333
発行日: 2012/08/20
公開日: 2013/11/08
ジャーナル フリーIn March 2011, there was an accident at the Fukushima Daiichi Nuclear Power Plant (NPP) and a discharge of radionuclides resulting from a powerful earthquake. Considering the impact on human health, the radiation dosimetry is the most important for 131I among radionuclides in the initial stage immediately following the release of radionuclides. Since 131I cannot be detected after several months owing to its short half-life (8 days), the reconstruction by 129I (half-life: 1.57 × 107 yrs) analysis is important. For this reconstruction, it is necessary to know the isotopic ratio of 129I/131I of radioactive iodine released from the NPP. In this study, the 129I concentration was measured in several surface soil samples collected around the Fukushima Daiichi NPP for which the 131I level had already been determined. The surface deposition amount of 129I was between 15.6 and 6.06 × 103 mBq/m2 within the region 3.6 to 59.0 km distant from the NPP. 129I and 131I data had good linear correlation and the average isotopic ratio was estimated to be 129I/131I = 31.6 ± 8.9 as of March 15, 2011.抄録全体を表示PDF形式でダウンロード (170K) -
SEBASTIAN O. DANIELACHE, CHISATO YOSHIKAWA, ANTRA PRIYADARSHI, TOSHIHI ...2012 年 46 巻 4 号 p. 335-339
発行日: 2012/08/20
公開日: 2013/11/08
ジャーナル フリーWe present a numerical study carried out with the SPRINTARS model modified to account for the radioactive decay of 35S compounds emitted from the Fukushima Daiichi nuclear power plant station after the hydrogen and vapor blast. The transport dynamics of the released material reproduced previous field observations. Four different emission scenarios were compared to the measurements of atmospheric 35S in sulfate collected in La Jolla, Tsukuba, Kashiwa and Yokohama. Linear regressions of the relation between emitted and transported material that reached the sampling sites were used to estimate the amount of 35S atoms and the amount of neutrons released in to the atmosphere. We estimate that a lower limit of 1.9 × 1016 35S atoms sec-1 were released after the events in March and this flux dropped to 4-39 × 1014 35S atoms sec-1 at the end of the month. Based on this calculations we estimated a lower limit of 5.2 × 1021 slow neutrons m-2 sec-1 were emitted from the nuclear fuel rods to the sea water injected in the reactors after the events in March.抄録全体を表示PDF形式でダウンロード (1045K) -
M. YAMAMOTO, T. TAKADA, S. NAGAO, T. KOIKE, K. SHIMADA, M. HOSHI, K. Z ...2012 年 46 巻 4 号 p. 341-353
発行日: 2012/08/20
公開日: 2013/11/08
ジャーナル フリー
電子付録A field survey was carried out soon after the Fukushima Dai-ichi Nuclear Power Plant accident. Gamma-ray emitting radionuclides and plutonium isotopes in a series of soil samples collected from the heavily contaminated areas outside the 20-km exclusion zone, as well as from Okuma Town adjacent to the plant, were measured. Volatile radionuclides such as 131I, 134Cs, and 137Cs contributed largely to the released radioactivity. Higher depositions of these nuclides were observed in areas to the northwestern—including Okuma Town and Iitate Village, which is at a distance of 25-45 km from the plant. The results obtained were consistent with the levels and distributions estimated later by the Japan-USA joint-survey (Asahi Shimbun Company, 2011). Trace amounts of plutonium isotopes originating from the accident were detected mainly in soil samples from Iitate Village and in limited soil samples from Okuma Town. The detected levels of 239,240Pu contamination due to the accident were considered to be less than a millionth those of the 137Cs contamination.抄録全体を表示PDF形式でダウンロード (5981K) -
AYA SAKAGUCHI, AKINOBU KADOKURA, PETER STEIER, KAZUYA TANAKA, YOSHIO T ...2012 年 46 巻 4 号 p. 355-360
発行日: 2012/08/20
公開日: 2013/11/08
ジャーナル フリーConcentrations of the radionuclides, U, Pu, and Cs were measured in water samples (10-20 L) to study analyte dispersion and migration following the Fukushima Daiichi Nuclear Power Plant (FDNPP) accident. A total of 8 water samples including oceanic water and paddy-field water were collected in the vicinity of the plant. Determinations of U, Pu and Cs isotopes were performed by accelerator mass spectrometry (AMS), inductively coupled plasma mass spectrometry (ICP-MS), and γ-ray spectrometry. The 236U/238U atom ratio was in the range 1.83-8.20 × 10-9 for fresh water and around 0.57 × 10-9 for seawater while the concentration of 236U was about 104-105 and 106 atoms/kg, respectively. Plutonium (239,240Pu) was detected in one riverine sample and the marine samples at very low levels and with large uncertainty. The concentrations of 137Cs in fresh riverine samples were 0.02-0.46 Bq/kg which are more than three orders of magnitude larger than the global fallout level. As for seawater samples within 80 km offshore of the FDNPP, the concentrations of 137Cs were 10-20 times higher than that of the Japan Sea water. Also 134Cs and 137Cs were of similar concentrations in all samples. The results show that volatile and refractory nuclides such as Cs, U and Pu exist in the dissolved phase, which can be readily assimilated by plants/humans. However the environmental impact of Pu and U in the vicinity of the FDNPP is considered to be low in comparison to that of the volatile radionuclide Cs.抄録全体を表示PDF形式でダウンロード (180K) -
JIAN ZHENG, TATSUO AONO, SHIGEO UCHIDA, JING ZHANG, MAKIO C. HONDA2012 年 46 巻 4 号 p. 361-369
発行日: 2012/08/20
公開日: 2013/11/08
ジャーナル フリーThe Fukushima Dai-ichi Nuclear Power Plant (DNPP) accident has caused serious contamination of the marine environment from atmospheric fallout deposition and the direct discharges of highly radioactive liquid wastes. In contrast to the immediate intensive studies on the distributions of released fission products, such as 131I, 134Cs and 137Cs, information on the possible contamination by actinides in the marine environment is quite limited. In this study, we report the first data-set on the distribution of Pu isotopes in surface sediments in the Pacific 30 km off Fukushima after the Fukushima DNPP accident. Activities of 239+240Pu and 241Pu, and atom ratios of 240Pu/239Pu and 241Pu/239Pu in surface sediments collected in July-August, 2011 were analyzed to make a quick assessment on the environmental impact of the possible Pu contamination. The observed 239+240Pu activities and 240Pu/239Pu atom ratios are comparable to those previously reported in marine sediments in the western North Pacific and its marginal seas, and in Japanese estuaries before the accident. The Pu contamination from the Fukushima DNPP accident was not observed in marine sediments outside the 30 km zone.抄録全体を表示PDF形式でダウンロード (1691K)
Express Letters
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KANGLE DING, YUE LUO, JINGFU SHAN, FUJIA GUAN2012 年 46 巻 4 号 p. e33-e37
発行日: 2012/08/20
公開日: 2013/11/08
ジャーナル フリーExperiments simulating reactions between pyrrole, hydrogen sulfide (H2S), and aluminum oxide (Al2O3) using a dynamic thermochemical process simulator were conducted to investigate the effect of organic-inorganic interactions on pyrrolic N compounds. The results showed that N-S atomic exchange occurred at 350°C with thiophene as the main product. Thermodynamic studies indicated the reaction of pyrrole with H2S could proceed spontaneously in most geologic settings (0-200°C). Thermochemical conversion of pyrrole into thiophene was found to be catalyzed by Al2O3 but inhibited by an increased volume of water. These findings suggest that conventional models may not fully account for the geochemical processes that result in the abundance and distribution of pyrrolic N compounds in sediments and crude oils. The organic-inorganic interactions in sedimentary basins may also have direct effects on the fate and preservation of pyrrolic N compounds in subsurface reservoirs.抄録全体を表示PDF形式でダウンロード (90K) -
HIKARU IWAMORI, HITOMI NAKAMURA2012 年 46 巻 4 号 p. e39-e46
発行日: 2012/08/20
公開日: 2013/11/08
ジャーナル フリーIn order to decipher the mantle geochemical heterogeneity that reflects material differentiation and circulation within the Earth, we examined mid-ocean ridge basalts (MORB), ocean island basalts (OIB) and arc basalts (AB), in terms of the radiogenic isotopic variability and its geographical distribution. It has been found that the Sr, Nd and Pb isotopic ratios of MORB, OIB and AB exhibit a two-dimensional structure, and are mostly distributed on the same compositional plane that is spanned by two independent components (IC1 and IC2). One of the two components (IC2) divides geochemically the mantle broadly into the Eastern and Western Hemispheres. Inspection of the geochemical nature of IC2 suggests that it may represent a fluid mobile component recycled through subduction zones. The mantle geochemical domain beneath the Eastern Hemisphere is enriched in the fluid mobile component, possibly by focused subduction towards the supercontinent Pangea which was surrounded by subduction zones. Although the present-day continents have been dispersed since then, the geochemical domain has seemingly been anchored to the asthenosphere without moving with the continents.抄録全体を表示PDF形式でダウンロード (3191K)
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