著者
渡辺 豊
出版者
日本地球化学会
雑誌
地球化学 (ISSN:03864073)
巻号頁・発行日
vol.50, no.1, pp.01_i-01_iii, 2016-03-25 (Released:2016-03-25)
著者
山本 政儀 坂口 綾
出版者
日本地球化学会
雑誌
地球化学 (ISSN:03864073)
巻号頁・発行日
vol.49, no.4, pp.173-184, 2015-09-25 (Released:2015-12-25)
参考文献数
25

Huge amounts of radionuclides were released into the atmosphere and ocean from the Fuku shima Dai-ichi Nuclear Power Plant (FDNPP), as a result of the reactor accident after the magnitude 9.0 Great East Japan Earthquake and subsequent gigantic tsunami on March 11, 2011. This paper summarizes our research activities on measurements of actinide elements (236U, 238,239,240,241Pu, 241Am and 242,243,244Cm) in the environmental samples.
著者
橘 省吾 澤田 弘崇 岡崎 隆司 高野 淑識
出版者
一般社団法人日本地球化学会
雑誌
地球化学 (ISSN:03864073)
巻号頁・発行日
vol.48, no.4, pp.265-278, 2014-12-25 (Released:2015-01-06)
参考文献数
101

Hayabusa2 is the sample return mission to the near-Earth C-type asteroid (162173) 1999 JU3 (2014–2020). Samples from C-type asteroids, which are abundantly present in the asteroid belt and of which reflectance spectra resemble those of carbonaceous chondrites, may well preserve the information covering the entire history of the Solar System; the epoch prior to the birth of the Sun, planetesimals and planet formation including a behavior of volatiles to terrestrial planets. Moreover, asteroidal surface samples record current surface geological processes and the dynamical evolution of small bodies in the Solar System, which are not recorded in meteoritic samples. The Hayabusa2 spacecraft will launch off in 2014, and arrive at the asteroid 1999 JU3 in mid-2018. Investigations by several remote sensing techniques and sample collections at three different locations will be carried out during its 18-month stay. The spacecraft will return to Earth with asteroidal samples in December 2020. In this article, we describe the outline and cosmochemical rationales of the Hayabusa2 mission with its significance in primitive small body exploration missions.
著者
大野 剛 村松 康行
出版者
日本地球化学会
雑誌
地球化学 (ISSN:03864073)
巻号頁・発行日
vol.49, no.4, pp.239-246, 2015-09-25 (Released:2015-12-25)
参考文献数
26

Inductively coupled plasma (ICP) is characterized by high ionization efficiency for almost all elements. Recently, a triple quadrupole ICP-MS (ICP-MS/MS) has been applied to the measurements of isotope ratios for ultra-low level radioisotopes. The ICP-MS/MS features an additional quadrupole mass filter situated in front of the octopole reaction cell and quadrupole mass filter, which allows only the analyte ion to enter the cell by rejecting all the other ions. In this manuscript, we review recent studies on environmental radioactivity in Fukushima achieved by ICP-MS/MS techniques.
著者
丸山 誠史 服部 健太郎 平田 岳史
出版者
日本地球化学会
雑誌
地球化学 (ISSN:03864073)
巻号頁・発行日
vol.48, no.3, pp.187-199, 2014-09-25 (Released:2014-10-10)
参考文献数
41

Concentrations of uranium and thorium in commercial bottled mineral waters (81 domestic and 11 foreign products) have been analyzed using ICP-MS. Domestic bottled mineral waters exhibit very wide range of the uranium concentrations (0.1–3300 ng/L). However uranium concentrations of most samples were below 100 ng/L. There is no obvious correlation between the values of hardness and the uranium concentrations of the domestic bottled mineral waters. The uranium concentrations of foreign bottled mineral waters tended to be much higher than those of domestic ones (up to 4000 ng/L), and the values of hardness correlate roughly with the uranium concentration. It may be due to interactions between limestone and groundwater. Thorium concentrations of both domestic and foreign bottled mineral waters are typically less than 3.0 ng/L. Concentrations of uranium and thorium in bottled mineral waters were greatly lower than provisional guideline values defined by WHO. Therefore, it can be considered that there is no health risk chemically/radioactively induced by natural uranium and thorium in commercial mineral waters currently available in Japan, especially in Kyoto City.
著者
飯島 和毅
出版者
日本地球化学会
雑誌
地球化学 (ISSN:03864073)
巻号頁・発行日
vol.49, no.4, pp.203-215, 2015-09-25 (Released:2015-12-25)
参考文献数
59

The Fukushima Dai-ichi Nuclear Power Plant accident led to the release of various and huge amount of radionuclides into the environment, and contamination of wide area of eastern Japan, mainly Fukushima prefecture. More than 70% of radioactive cesium, which dominates the exposure dose, was deposited in forest far from our living sphere and is considered to be remobilized with time by water flow and strong wind caused by natural events such as typhoons. Numerous researches on the behavior of radionuclides in the environment have been performed not only by observation in the contaminated regions but also by model analysis so far. This paper overviewed results of understanding and modeling of transport behavior of radiocesium from forests through river systems.
著者
足立 光司
出版者
日本地球化学会
雑誌
地球化学 (ISSN:03864073)
巻号頁・発行日
vol.49, no.4, pp.185-193, 2015-09-25 (Released:2015-12-25)
参考文献数
27

Water-insoluble radioactive materials emitted during an early stage of the Fukushima Dai-ichi Nuclear Power Plant accident in 2011 were identified, and their chemical and physical properties were characterized as particulate matters. In this report, studies on radioactive particles collected from filter samples in Tsukuba on March 14–15, 2011 are summarized. Their compositions, chemical states, sizes, shapes, crystallinity, and hygroscopicity were analyzed using microscopic analyses such as electron microscopy and synchrotron with a micro-beam. The results indicate that they include Cs, Fe, and Zn as well as elements from fission products and are water insoluble, spherical-glassy particles with ca. 2 micrometer in size. Understanding of their detailed properties is significant to improve the numerical models during the accident and to understand their occurrences in soil as well as the accident itself. In addition to the water-insoluble radioactive materials, water-soluble radioactive materials, which were likely emitted in different events during the accident, should be investigated to have comprehensive understanding of the accident and its environmental effects. More samples from various environments such as soil will be needed, and more detailed chemical and physical analyses will help to understand their formation process, influences on human health, and long term decrements in ambient conditions.
著者
小暮 敏博 向井 広樹 甕 聡子
出版者
日本地球化学会
雑誌
地球化学 (ISSN:03864073)
巻号頁・発行日
vol.49, no.4, pp.195-201, 2015-09-25 (Released:2015-12-25)
参考文献数
13

Mineral species that really retain radioactive cesium in Fukushima soil have been investigated by analyzing actual contaminated soil samples in Fukushima using IP autoradiography, electron microscopy and X-ray diffraction. Weathered biotite originated from granitic body in Fukushima was frequently found as radioactive fine particles. The weathered biotite is mineralogically a biotite-vermiculite mixed-layer mineral. Besides, smectite-like clay mineral was identified in biotite-free particles using X-ray diffraction. A new cesium-sorption experiment was conducted, in which various clay minerals were immersed together in dilute 137Cs radioisotope solutions and the amount of 137Cs adsorbed in each mineral was measured by IP autoradiography to reproduce the sorption at actual concentration level in the radioactive particles. It was found that 137Cs was sorbed predominantly by the weathered biotite collected in Fuku shima, confirming the results from the investigation of the actual contaminated soil mentioned above.
著者
本多 牧生
出版者
日本地球化学会
雑誌
地球化学 (ISSN:03864073)
巻号頁・発行日
vol.49, no.4, pp.227-238, 2015-09-25 (Released:2015-12-25)
参考文献数
27

Settling particle collector, sediment trap, has played an important role in the study of spatiotemporal variability in biogeochemical particles' cycle in the ocean. This report reviews the observational study of behavior (such as dispersion, distribution and existence form) of particulate artificial radionuclides in the ocean emitted from severe accidents of two nuclear power plants (Chernobyl NPP and Tokyo Electric Power Corporation Fukushima Dai-ichi NPP) by using time-series sediment trap.
著者
北台 紀夫 青野 真士 大野 克嗣
出版者
日本地球化学会
雑誌
地球化学 (ISSN:03864073)
巻号頁・発行日
vol.50, no.3, pp.155-176, 2016-09-25 (Released:2016-09-25)
参考文献数
156

The origin of life must be studied through addressing a problem of the emergence of a free-energetically open complex system, rather than a problem of abiotic syntheses of various building blocks of life (Aono et al., 2015). One of the key aspects of the origin question is the origin of metabolism, since no (genetic) information may be preserved without ample and ordered materials supply. Thus, from the perspective of the origin of ‘proto-metabolism' we critically review currently prevailing approaches to the origin problem. Then, referring to the latest biological and geochemical findings, we will describe a scenario of the electrochemically driven emergence of ‘proto-metabolism' together with experimental proposals.
著者
田中 万也 高橋 嘉夫 福士 圭介 宇都宮 聡
出版者
日本地球化学会
雑誌
地球化学 (ISSN:03864073)
巻号頁・発行日
vol.49, no.4, pp.169-171, 2015-09-25 (Released:2015-12-25)

Many studies have been carried out since the Fukushima Dai-ichi Nuclear Power Plant (FDNPP) accident. Here, we would like to introduce the special issue on the FDNPP accident which includes contributions from various fields covering aerosols, soil, forest, river, ocean and application of new analytical technique to samples collected in Fukushima.
著者
癸生川 陽子
出版者
日本地球化学会
雑誌
地球化学 (ISSN:03864073)
巻号頁・発行日
vol.50, no.3, pp.211-225, 2016-09-25 (Released:2016-09-25)
参考文献数
105

I have been studying origin and evolution of extraterrestrial organic matter on the basis of experimental kinetic approaches that enable us to predict changes in its molecular structure and chemistry during parent body processes. Here I summarize experimental studies of organic solid formations starting from formaldehyde and ammonia with the presence of liquid water, and decreasing in aliphatic C–H bonds as observed in infrared spectra with heating experiments of Murchison meteorite. The related works are also reviewed and the applications for deciphering thermal histories of asteroids are discussed.
著者
石渡 良志 内田 邦子 長坂 洋光 塚本 すみ子
出版者
日本地球化学会
雑誌
地球化学 (ISSN:03864073)
巻号頁・発行日
vol.44, no.3, pp.69-76, 2010

A 90 cm sediment core (HAR 99A) from Lake Haruna, Gumma Prefecture, Japan was dated by tephrochronology, lead-210 and cesium-137 methods and was compared stratigraphically with the cores obtained in 1966 (HAR 96B) and 1971 (HAR 71). For the HAR 99A core, the 24-26 cm depth layer was estimated to be AD 1963 by <sup>137</sup>Cs. The tephra layer in 62-66 cm depth was identified to be volcanic ashes from Asama volcano eruption (Asama-A tephra: As-A) in AD 1783. Average mass sedimentation rate (AMSR) for 1963 to 1999 (0-26 cm depth) is 0.050 g cm<sup>-2</sup>yr<sup>-1</sup> and that for 1783 to 1963 (25-62 cm depth) is 0.033 g cm<sup>-2</sup>yr<sup>-1</sup>. AMSR for the 0-62 cm depth obtained by <sup>210</sup>Pb ranges between 0.052 and 0.058 g cm<sup>-2</sup>yr<sup>-1</sup>. In addition, it is proposed that the previous assignment of As-B (AD 1108) for a tephra layer at 40-50 cm depth of the HAR 71 core should be changed to As-A tephra (AD 1783).
著者
西尾 嘉朗
出版者
一般社団法人日本地球化学会
雑誌
地球化学 (ISSN:03864073)
巻号頁・発行日
vol.40, no.2, pp.83-96, 2006-05-25 (Released:2017-01-25)
参考文献数
64
被引用文献数
1

The non-traditional lithium (Li) isotopic tracer has a great potential to provide a major breakthrough in the investigation of the material cycle in the terrestrial mantle. Using a developed multiple-collector ICP mass spectrometry method, we revealed Li isotopic systematics of mantle-derived samples. The main significance in our results is the finding of extremely low 7Li/6Li values in several mantle-derived samples. Based on earlier results for eclogites, it had been proposed that subducted highly altered oceanic crust would have extremely low 7Li/6Li values. The significantly low 7Li/6Li values, however, had never been observed in any mantle-derived samples before our finding. We have also proposed that the enrichment of isotopically light Li may be general property of the enriched mantle type 1 end-member component (EM 1). In this scenario, the Li in the EM 1 source mainly originates from Li in the highly altered basalt of the uppermost part of subducted oceanic crust. Thus, the Li isotopic signature is sensitive to the degree of alteration experienced by the basaltic crust and can thus be used to distinguish what part of the basaltic crust was recycled.
著者
東田 盛善 佐竹 洋 渡久山 章
出版者
日本地球化学会
雑誌
地球化学 (ISSN:03864073)
巻号頁・発行日
vol.35, no.1, pp.27-41, 2001
被引用文献数
6

Spring waters from limestone terrains of the southern area of Okinawa Island have been analysed for chemical and isotopic compositions. The isotopic compositions of river waters from the central and northern areas of the island have also been measured. Spring and river water samples were collected during the following periods: spring waters from April 26th to June 28th, river waters June 1 st and 2nd, and July 20, 21 and 22, 1996, respectively. P<sub>CO2</sub> of spring waters is 10<sup>-2.3</sup> to 10<sup>1.1</sup> atm. These high P<sub>CO2</sub> are probably caused by a large supply and fast decomposition of litter, owing to the climatic characteristics of the island. High concentrations of Ca<sup>2+</sup> and HCO<sub>3</sub><sup>-</sup> in spring waters may be caused by the reaction of limestone with CO<sub>2</sub>. High concentrations of SO<sub>4</sub><sup>2-</sup>, HCO<sub>3</sub><sup>-</sup> and excess Na<sup>+</sup> (Na<sup>+</sup> of non sea water origin) are found in spring waters from the southern area. These Ca-SO<sub>4</sub>・HCO<sub>3</sub> type spring waters are possibly formed by oxidation of pyrite occurring in the bedrock (Shimajiri Group). Equilibrium relationships among the spring water, feldspar, and clay mineral suggest that spring waters may be equilibrated with kaolinite. The NO<sub>3</sub><sup>-</sup>-N content of spring waters has been increased by contamination with chemical fertilizers and waste waters from domestic areas. The increment is striking in the central areas, comparing with data of 1987. Values of δD and δ<sup>18</sup>O for spring and river waters are -36 to -18‰ and -5.6 to -3.3‰, respectively. These values are almost the same with those of groundwaters in Hateruma and Yonaguni Islands, located about 2° south of Okinawa Island. This is probably due to that the water vapor in these areas are mainly recharged from the sea around the islands. The d-parameter (d=δD-8δ<sup>18</sup>O) of spring and river waters ranges from 2.8 to 13.4 with an average of 8.6. This indicates that these waters are mainly recharged with precipitations from the Pacific Ocean airmass in summer.
著者
淵田 茂司
出版者
日本地球化学会
雑誌
地球化学 (ISSN:03864073)
巻号頁・発行日
vol.49, no.4, pp.247-259, 2015-09-25 (Released:2015-12-25)
参考文献数
87

Amino acids, necessary to form life body, are present in greater abundances in natural seafloor hydrothermal fluids over 200℃ than in ambient seawater, although these are unstable and decomposed rapidly under simulated hydrothermal conditions. Serine and aspartic acid, which are thermally labile amino acids, are detected in the high temperature fluids. Inorganic matters such as metal ions and minerals could protect these labile amino acids in the fluids. Most of the dissolved amino acids are combined form and L form, suggesting that these are derived from organisms around hydrothermal vents. In addition, low levels of non-protein amino acids content indicate that amino acids are fresh and not experienced thermal alteration for long time. Amino acids are important as common sources of carbon and nitrogen for heterotrophic marine microbes. The release of biogenic amino acids along circulation paths of hydrothermal fluids could be effective for the development of hydrothermal vent fauna. In this paper, I review the origins and characteristics of dissolved amino acids in the natural hydrothermal fluids and implicates importance of the biogeochemical cycle of nitrogen and carbon around hydrothermal venting in detail.
著者
松本 英二
出版者
日本地球化学会
雑誌
地球化学 (ISSN:03864073)
巻号頁・発行日
vol.17, no.1, pp.27-32, 1983
被引用文献数
13

The aim of this paper is to review the sedimentary environment in the Tokyo Bay. Great emphases were placed to the sedimentation rate and heavy metal and organic pollution to reveal the history of pollution and environmental changes in the Tokyo Bay.
著者
奥地 拓生
出版者
一般社団法人日本地球化学会
雑誌
地球化学 (ISSN:03864073)
巻号頁・発行日
vol.33, no.4, pp.247-254, 1999
参考文献数
37

The fate of H<sub>2</sub>O accreted to the primordial Earth is discussed using the results of the hydrogen partitioning experiments between molten iron and silicate melt at high pressure. Previous works related to this problem give no weight to the partitioning of hydrogen into the core, so that the origin and abundance of H<sub>2</sub>O in the hydrosphere, crust and mantle of the present Earth should be reconsidered from the viewpoint of the evolution of the primordial Earth including core formation processes. The results indicate that there is large possibility for most of H<sub>2</sub>O accreted to the Earth to be transported into the core as molten iron hydride (FeH<i>x</i>), rather than to be left into the hydrosphere and mantle in every case of H<sub>2</sub>O concentration in the accreting planetesimals. In other words, the mantle must have been dried up after the core formation. These results are consistent with the observed H<sub>2</sub>O concentration in the hydrosphere, crust and upper mantle of the present Earth. The presence of hydrogen in the core may quantitatively settle the problem of density deficit of the present Earth's core.