著者
新村 龍也 沢田 健
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.1, pp.17-29, 2010
被引用文献数
2

Dietary preferences of archaeological and paleontological animals have been investigated based on stable carbon isotope ratios (δ<sup>13</sup>C) of collagen and non-collagenous proteins in fossil bones. The δ<sup>13</sup>C of individual compound in lipids from fossil bones were recently applied to the reconstruction of palaeodietary of animals. In the present study, we analyze the concentrations, class distributions, and δ<sup>13</sup>C values of fatty acids and steroids in the Pleistocene to Pliocene fossil whale and the Miocene fossil sea cow (<i>Dusisiren</i> sp.) bones, and evaluate their applicability as indicators of palaeodietary and fossil diagenesis. Biosynthetic steroids as cholesterol are detected in the Pleistocene whale bones, while the sterols are very poor in the older Pliocene whale samples, of which major steroids are their diagenetic compounds such as cholestanes and cholestenes. However, a large amount of cholesterol characterizes the Miocene fossil sea cow bone. We also can identify labile unsaturated fatty acids from all fossil whale and sea cow bones. It is suggested that the relative abundances of unsaturated to saturated fatty acids can be useful indicator for estimating diagenetic stage of fossil bones and checking contamination. The δ<sup>13</sup>C values of fatty acids in the fossil whale and sea cow bones range widely from -25.7 to -16‰, and there are differences of 1 to 4‰ between several fatty acid homologues within the same sample. Thus, the δ<sup>13</sup>C analyses of fatty acids in fossil bones may be less applicable for reconstructing palaeodietary. On the other hand, the δ<sup>13</sup>C values of steroidal compounds within the same sample are almost similar, although these values vary ranging between -29.6‰ and -24.4‰ among the different whale samples. Furthermore, the steroidal δ<sup>13</sup>C value in the sea cow sample is -20.5‰, which is concordant with that of food in sea cow. From these results, the δ<sup>13</sup>C value of steroid in fossil bone can be strongly useful tool for reconstructing palaeodietary of paleontological animal.
著者
小路 翔子 笹木 康平 上田 晃 中本 利正
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.2, pp.97-114, 2016-06-20 (Released:2016-06-20)
参考文献数
38
被引用文献数
1

Chemical and isotopic (δD and δ18O) compositions of 30 hot spring waters and 5 river waters in Okuhida Hot Springs, Gifu, were investigated to examine the geochemical characteristics and geothermal resources. Most hot springs were of meteoric origin and of Na+–Cl-・HCO3- and Na+–HCO3- types with low salinity (less than 30 meq/L). In the study area, meteoric water infiltrates into ground and is heated by magmatic source and enriched in Ca2+and HCO3- during interaction with underlying carbonate rocks. A part of the hot spring is enriched in CO2 due to contribution of CO2-rich volcanic fluid. The estimated underground temperatures by several geothermometers are 150 to 200℃ at the depth of ca. 1 km. The total geothermal resources in the study area are estimated to be ca. 400 MWe for producing the electricity. In the study area, most hot springs have been provided for bathing in hotels and a part of them (60℃, 3,000 L/min) has not been used. We provide this unused geothermal energy to apply for snow melting on road and room heating. For the safety use of geothermal resources in the study area, scaling problem was considered. On the basis of the saturation index of several minerals from the observed chemical compositions of hot spring waters, calcite scale is expected to be precipitated in the reservoir and in the production wells and should be considered to prohibit the precipitation.
著者
八代 尚 滝川 雅之 須藤 健悟 菅原 敏 青木 周司 中澤 高清
出版者
日本地球化学会
雑誌
日本地球化学会年会要旨集
巻号頁・発行日
vol.56, pp.233-233, 2009

大気中水素(H<SUB>2</SUB>)はメタンに次いで濃度の高い反応性気体であり、土壌細菌による消費を主な吸収源とすることから、陸域-大気間の相互作用を研究する上で有用なトレーサーである。本研究において観測された日本上空のH<SUB>2</SUB>濃度は明瞭な鉛直勾配を示し、地表付近での大きな季節変動が明らかになった。全球三次元化学輸送モデルCHASERを用いたH<SUB>2</SUB>濃度の計算結果はおおむね観測結果を再現するが、北半球で秋から冬にかけて過小評価の傾向を示し、より詳細な吸収過程の表現を必要とすることが示された。
著者
長尾 誠也
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.217-226, 2015-09-25 (Released:2015-12-25)
参考文献数
43

This paper reviewed the transport behavior of 137Cs in river systems of Fukushima Prefecture, Japan after the Fukushima Dai-ichi Nuclear Power Plant accident during 2011–2014. Total radioactivity of 137Cs in water samples from the Abukuma River and small watershed river systems in eastern Fukushima, Hama-dori region, decreases exponentially with increasing time after the accident at normal flow condition. Higher radioactivity was found at higher flow condition caused by rain events. Particulate phase of 137Cs in river waters ranged from 60 to 99% to total radioactivity. Apparent distribution coefficient (Kd value) of 137Cs was 102 to 103 l g-1. The annual export of 137Cs from land to coastal ocean was estimated as 1010 to 1013 Bq in the river basins on the basis of field research data. These results indicate that major part of 137Cs is exported as particulate forms associated with suspended solids in the river waters.
著者
松野 弘貴 中町 鴻 本多 照幸 木川田 喜一
出版者
日本地球化学会
雑誌
日本地球化学会年会要旨集
巻号頁・発行日
vol.60, 2013

2011年3月11日に発生した東北太平洋沖地震(M9.0)(以下東日本大震災)によって、福島第一原子力発電所の原子炉の事故が発生しその結果、1~4号機の原子炉建屋で水素爆発が生じ、大量の放射性物質が大気中に放出された(Ⅰ-131等価で77万兆ベクレル)。 その結果、関東地方(東京都市大学原子力研究所・川崎市西部)でも人工放射性核種Cs-134、Cs-137が検出された。福島原発事故により飛来した、これらの人工放射性核種を調査することで、事故による大気拡散や大気環境への影響を解明する端緒となることが期待される。 本研究では、東京近郊の川崎市郊外を中心とした事故直後と1年後の大気試料中のγ線放出核種(Cs-134、Cs-137)の解析結果について報告する。更に放射性Csの化学形態を調査するためにCsの抽出実験を行ったので報告する。
著者
下島 公紀 前田 義明 間木 道政
出版者
日本地球化学会
雑誌
日本地球化学会年会要旨集
巻号頁・発行日
vol.54, pp.129-129, 2007

活動的な海底地殻で起こっている海底熱水活動域では,天然の状態でCO2が放出されている。熱水中にはマグマ起源のCO2が高濃度に含まれており,熱水噴出孔から放出された後は,高CO2濃度・低pHの熱水プルームとして深層水中に拡散するという現象が繰り広げられている。海底熱水活動域では、溶解したCO2によって高CO2濃度・低pHの環境が発生していることが予想されるため,熱水活動地帯における液体CO2の挙動観測は,CO2貯留の環境影響評価のナチュラルアナログとして最適である。
著者
伊古田 博嗣 岡田 孝一郎 黒木 由貴子 新垣 雄光
出版者
日本地球化学会
雑誌
日本地球化学会年会要旨集
巻号頁・発行日
vol.52, pp.80-80, 2005

海水中の過酸化物の生成起源は、海水中での光化学反応と大気中の過酸化物の海水への乾性沈着、雨の日は大気中の過酸化物の雨水中への溶け込みとその湿性沈着などが考えられている。また、海水中でのオゾンの生産量、光活性物質の濃度、入射光、海面での透過度や光の波長域などの因子が大きく影響していると報告されている。そこで、本研究では晴れの日の海水中の過酸化物のソースを明らかにすることを目的に以下の3項目について研究を行った。まず、海水中の過酸化物に対する海水の循環や潮汐の影響を考察する。次に、乾性沈着の影響を考察する。さらに、大気中の過酸化物の日周変化を測定し、過去の測定結果との比較を行う。
著者
高橋 浩 風早 康平 高橋 正明 稲村 明彦
出版者
日本地球化学会
雑誌
日本地球化学会年会要旨集
巻号頁・発行日
vol.60, 2013

トリチウムを指標として深部流体の化学組成を求めるための解析をシオワッカ、鹿塩、有馬・宝塚、津和野において実施した。推定された深部流体の化学成分は、どの地域もNa-Clが主要成分であるが、宝塚や有馬でCaに富み、津和野やシオワッカでMgに富む傾向があった。さらに、炭素成分にバリエーションが見られた。深部流体に特徴的な成分であるCO2、ClとH2Oについて見てみると、有馬、宝塚、津和野におけるC/Cl比はおおよそ一致し、H2Oとの比が変化している。全炭酸-Cl-Liの比では、有馬・宝塚の方が津和野よりもわずかに高いLi/Cl比を示すものの、非常に似た組成を示した。このことは、有馬・宝塚と津和野では共通した深部流体端成分を示唆し、トリチウムを含まない淡水による希釈の影響を示す。一方、鹿塩地域では、Li/Cl比も有馬・宝塚・津和野より高かった。これは、深部流体の上昇過程において、地層との反応が起きているためと考えられる。
著者
高地 吉一 折橋 裕二 小原 北士 藤本 辰弥 春田 泰宏 山本 鋼志
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.1, pp.19-35, 2015-03-25 (Released:2015-03-30)
参考文献数
44
被引用文献数
1

We carried out an optimization of analytical parameters for U–Pb zircon dating by laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) using a NIST SRM 610 glass. As a result, we obtained the following optimum analytical parameters: laser energy: 11.7 J/cm2, repetition rate: 10 Hz, pre-ablation time: 8 sec, integration time: 10 sec and crater diameter: 25 μm. The average 206Pb/238U ratio of the NIST SRM 610 glass normalized by a 91500 zircon standard under the conditions mentioned above was 0.2236±0.0044 (1σ, N : 87). The median value of this result matches with that of the literature value within range of the analytical precision. Furthermore, the 206Pb/238U weighted mean ages of the Plešovice, OD-3 and Fish Canyon Tuff zircons, having the proposed 206Pb/238U ages of 335.48±0.95 Ma (95% conf., N : 38, MSWD : 1.1), 33.25±0.38 Ma (95% conf., N : 23, MSWD : 1.5), 28.56±0.49 Ma (95% conf., N : 34, MSWD : 5.1), respectively, were measured, normalized by the NIST SRM 610 glass standard. The results were consistent within 1% error range of the recommended values. These results suggest that the matrix effect can be reduced to less than analytical precision on materials with different physical properties under well-optimized analytical conditions.
著者
南 秀樹 加藤 義久 和田 秀樹 岡部 史郎
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.29, no.2, pp.85-97, 1995
被引用文献数
7

Four cores, which penetrated into the Holocene, were collected in 1985-1986 from the center to mouth of Lake Hamana, Japan. Sediments were analyzed for the concentrations of organic C, total N, biogenic SiO<sub>2</sub>, Mg, Al, Fe, Mn, V and P. The age of the sediment near the bottom part of each core, which exhibited a higher C/N mole ratio, changed from 11,000 yr B. P. at the mouth to 7,000 yr B. P. at the center part of the lake. This indicated a higher sedimentation of land plants enriched in carbon, which probably took place during a period of high sealevel. After 4,000 yr B. P. in the inner part of the lake there were some distinctive changes in the distributions of elements, as related to their <sup>14</sup>C ages : (1) higher content and large fluctuations in both the sediment, organic carbon and biogenic SiO<sub>2</sub>, and (2) an excess organic carbon over biogenic SiO<sub>2</sub>. Yet, in contrast, the C/N mole ratio&ap;12 remained constant. These observations suggested that an eutrophic and productive lake was formed when the seawater exchange was restricted. The contents of Fe and Mg also increased remarkably after 4,000 yr B. P. These changes are due to increasing of the transport ation of particles, originating from ultra-basic rocks carried by the Miyakoda River in the northern part of the lake. Before this period marine silt was predominantly transported from the Pacific sea side.
著者
鶴田 治雄 中島 映至
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.46, no.2, pp.99-111, 2012
被引用文献数
1

Massive radioactive materials were released into the atmosphere after the accident of the Fukushima Daiichi Nuclear Power Plant (FD1NPP) caused by the Tohoku Earthquake and Tsunami on 11 March 2011, and transported and deposited to the land surface in a regional scale. A large amount of dataset has been opened such as the routine monitoring of radiation dose, fallout, and the regional map of radionuclides deposited to the surface soils by an intensive field measurement and aircraft monitoring by MEXT. In contrast, continual field measurements for atmospheric radioactivity were made only at seven stations in the Kanto area, while they are necessary to evaluate the initial radiation exposure, to validate results of atmospheric transport models, and to estimate the emission inventory of radionuclides. In this review, the following five points are introduced. (1) Summary of release rate estimation from the FD1NPP by the combination of WSPEEDI-II with atmospheric radioactivity of <sup>131</sup>I and <sup>137</sup>Cs and radiation dose. (2) The possible mechanisms of many peaks of radiation dose during 11-16 March 2011 which were measured at the monitoring posts near the FD1NPP. (3) Possible mechanism of regional transport and the surface deposition of radionuclides. (4) Summary of atmospheric <sup>131</sup>I in aerosols and gases, and <sup>131</sup>I/<sup>137</sup>Cs in the atmospheric radioactivity. (5) An intensive one-year field measurement of atmospheric radioactivity of <sup>137</sup>Cs at Fukushima and Koriyama since May 2011.
著者
遠嶋 康徳
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.77-93, 2010

Observation of the change in atmospheric O<sub>2</sub> concentration, combined with atmospheric CO<sub>2</sub> observation, provides complementary information about the global carbon cycle. This is based on the fact that O<sub>2</sub> and CO<sub>2</sub> fluxes are tightly coupled during terrestrial photosynthesis, respiration, and fossil fuel and biomass burning, but are less or decoupled during the sea-air gas exchanges. Especially, the long-term O<sub>2</sub> changes can be used to partition the sequestration of fossil fuel CO<sub>2</sub> release between ocean and terrestrial biosphere. In this review, we examine the parameters used for the partitioning calculation, including - O<sub>2</sub>: C exchange ratios for the terrestrial photosynthesis/respiration and fossil fuel burning. In early atmospheric O<sub>2</sub> studies, the net oceanic O<sub>2</sub> flux was assumed to be zero because of the low solubility of O<sub>2</sub> in seawater in comparison with that of CO<sub>2</sub>. However, recent studies have suggested that the upper-ocean warming, reducing the solubility of O<sub>2</sub> and the oceanic ventilation, causes net oceanic O<sub>2</sub> outgassing. We also review approaches to estimate the net oceanic O<sub>2</sub> fluxes. Finally, using the updated fossil CO<sub>2</sub> emission estimates and recently reported warming rates of the global upper ocean, we recalculate the ocean and terrestrial carbon sinks based on the previously reported atmospheric O<sub>2</sub> observations.
著者
中澤 高清
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.16, no.2, pp.63-77, 1982

In view of the importance of the global increase in atmospheric CO<sub>2</sub> for climatic change, extensive studies have been made on the concentration of atmospheric CO<sub>2</sub>. In this paper, the results obtained from these studies are summarized together with those of our own measurements. Methods for measurement of the atmospheric CO<sub>2</sub> concentration by infrared absorption techniques are also described.
著者
北野 康
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.16, no.2, pp.59-62, 1982

It was reported that since 1850 human activities have increased the CO<sub>2</sub> content of the terrestrial atmosphere from 290 ppm to slightly more than 330 ppm. It is thought that the CO<sub>2</sub> content would reach twice the current CO<sub>2</sub> content by the year 2020 and at that time there will have been a rise in the average air temperature of about 2℃. This has produced a serious fear that a climatic change will occur and reduce some of the present granary regions to rather arid areas. Thus atmospheric CO<sub>2</sub> studies should be one of the most urgent research subjects internationally. Y. Kitano has organized the research group on "The cycle of carbon dioxide through the phases of the atmosphere, hydrosphere and biosphere" in connection with the atmospheric CO<sub>2</sub> problem, sponsored by the Ministry of Education in Japan as a Special Project Research on Environmental Sciences. It is happy to show the results obtained by some members of the research group here.
著者
佐野 有司 高畑 直人 堀口 桂香 植木 貞夫 中島 淳一 長谷川 昭
出版者
日本地球化学会
雑誌
日本地球化学会年会要旨集
巻号頁・発行日
vol.53, pp.250-250, 2006

日本列島においても温泉や火山、天然ガスなどを通じて固体地球から揮発性元素が定常的に脱ガスされている。これらの中でマントル起源であることが明らかなヘリウムー3と地殻起源のヘリウムー4の比のマッピングをすることで、日本列島におけるテクトニックな場をヘリウム同位体比がどのように反映するか1980年代から研究されてきた。一方、地震波の高精度データが蓄積し、その解析法に進歩があり、地下の構造を示す地震波トモグラフィーの詳細な研究が行われつつある。本研究では、これまでに蓄積されたヘリウム同位体比のデータをコンパイルし、そのマッピングと地震波トモグラフィーのデータを比較検討し、日本列島における脱ガス過程と地下構造の関係について発表する。
著者
小坂 丈予 小坂 知子 平林 順一 大井 隆夫 大場 武 野上 健治 木川田 喜一 山野 眞由美 油井 端明 福原 英城
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.31, no.2, pp.119-128, 1997
被引用文献数
7

Geochemical study on Yugama, a crater lake at Kusatsu-Shirane volcano, has been conducted since 1966. Amounts of various cationic species in Yugama water started increasing around 1981, slightly before the phreatic eruptions in 1982-1983, and kept increasing until 1985. In 1986, they turned to decrease and at present restore their former levels before the eruptions. The concentration of sulfate ion showed a secular change similar to those of cationic species, but no such variation was observed for chloride ion even during the 1976 and 1982-1983 eruptions. However, it started increasing in 1989. A high correlation between the concentrations of chloride and hydrogen ions suggests an increasing influx of hydrogen chloride from the deep volcanic systems under the lake. A Cl<sup>-</sup>-SO<sub>4</sub><sup>2-</sup> is an excellent monitor of the variation in volcanic activity at Kusatsu-Shirane volcano; all of the three past activities since 1966, i.e., the high-level subsurface activity in 1968, the eruption in 1976 and the eruptions in 1982-1983, showed a reverse secular change with time in the Cl<sup>-</sup>-SO<sub>4</sub><sup>2-</sup> plot. This could be attributable to the function of Yugama water as a condenser of volatiles released underground.
著者
友寄 喜貴 棚原 朗 武村 盛久 渡口 輝 平良 初男
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.31, no.4, pp.227-233, 1997
被引用文献数
3

The activities of natural radionuclides, <sup>238</sup>U, <sup>234</sup>U, <sup>226</sup>Ra, <sup>228</sup>Ra, <sup>222</sup>Rn, <sup>210</sup>Pb and <sup>210</sup>Po in ground waters collected from Okinawa Island were measured. The <sup>234</sup>U/<sup>238</sup>U activity ratios in most samples showed more or less unity, whereas, relatively high values of 2.0-4.0 were obtained in samples from Motobu area. <sup>222</sup>Rn activities in the ground waters were much higher than the other uranium series nuclides. The <sup>222</sup>Rn/<sup>226</sup>Ra activity ratios ranged from 3000 to 29000, and those for <sup>210</sup>Po/<sup>210</sup>Pb were from 0.08 to 0.82. On the whole, activities of the nuclides in the ground waters at the studied points showed higher in the order of <sup>222</sup>Rn≫<sup>210</sup>Pb><sup>234</sup>U><sup>238</sup>U><sup>226</sup>Ra><sup>210</sup>Po. In addition to α_recoil dissolution, the selective absorption and/or desorption by some organic or inorganic substances in the aquifer may be happening.