著者

加藤 真悟

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.49, no.1, pp.1-17, 2015-03-25 (Released:2015-03-30)

参考文献数

87

被引用文献数

2

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Iron is a key element to understand global biogeochemical cycling. Microorganisms are involved in redox cycling of iron in natural environments. In particular, neutrophilic iron-oxidizing microorganisms that grow at circumneutral pH potentially play a significant role in global iron oxidation at redox boundaries. However, little is known about neutrophilic iron-oxidizing microorganisms because only a few cultivated species have been reported to date despite a long research history. In this review, knowledge about neutrophilic iron-oxidizing microorganisms, i.e., phylogeny, physiology, ecology, spatial distribution, and unique extracellular polymeric substances, is summarized, including the most recent reports. This will provide useful information to various scientific fields: not only microbiology, but also geochemistry, astrobiology and environmental engineering.

著者

北台 紀夫

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.53, no.3, pp.91-105, 2019-09-25 (Released:2019-09-25)

参考文献数

116

---

How and where did life on Earth originate? Did the life’s origin happen from a combination of a huge number of geological events that were specially and temporally separated from each other, or did it occur within a local environment through a series of chemical processes that were compatible with the conditions prevailing within the setting? One of the key sites to resolve these questions is deep-sea hydrothermal systems, where the emergence of protometabolism through sulfides-promoted abiotic CO2 fixation has long been suggested to be the most plausible initial process toward the origin of life. However, geochemical mechanisms to harness the reductive power provided by hydrothermal systems remain to be elucidated. Here, this review introduces “geoelectrochemistry” as a general potent means to realize protometabolism at the vent–seawater interface in early ocean hydrothermal systems. Based on the relevant field, laboratory, and theoretical investigations of these systems, together with the latest astronomical observations of extraterrestrial planets/satellites, the fundamental nature of driver for life are discussed as a base to consider the ubiquity and similarity of life in Universe.

著者

唐牛 譲 石橋 之宏 上椙 真之 矢田 達 中藤 亜衣子 熊谷 和也 岡田 達明 安部 正真

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.211-220, 2014-12-25 (Released:2015-01-06)

参考文献数

17

被引用文献数

1

---

The Extraterrestrial Sample Curation Center of JAXA curates the Hayabusa-returned samples in conditions of minimum terrestrial contaminants, because these samples are very tiny. We evaluated the cleanliness of the handling instruments, the cleanroom environments and the sample storage chamber to improve the cleanliness of particles, organic molecules and metallic elements to a level not to affect the analyses of the Hayabusa-returned samples. In the environment of the clean chamber No. 2 where the samples have been stored, the organic molecule abundance was lower than the detection limit, furthermore, metallic elemental concentrations were the lowest among other evaluated place. A multi-stage ultrasonic cleaning by organic solvents and the ultrapure water have been applied to instruments made of stainless steel and/or aluminum alloy, and additionally, acid-alkali liquids cleaning have been performed for those made of quartz glasses. For the cleanliness of quartz glasses after the cleaning, the organic molecules abundances were blank level, and the metallic element concentrations were 1~100×109atom/cm2/24 h. It was confirmed by optical microscope that no particle of size more than 10 μm was observed on quartz glasses after the cleaning.

著者

西田 梢

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.56, no.1, pp.1-17, 2022-03-25 (Released:2022-03-25)

参考文献数

96

---

Climate changes, such as global warming and ocean acidification, are projected to affect survival, growth, and metabolic and physiological activities in marine calcifiers. To improve understanding of the future climate and its impact on marine calcifiers, development of environmental and ecological proxies by using culture experimental and isotope geochemical approaches are important. This review undertook recent advances in (1) culture experimental study that has implications for understanding the evolution of biomineralization and future impact on marine calcifiers, and in (2) environmental and ecological proxies by using stable and radio isotopes of biogenic carbonate to enhance understanding of the climate reconstruction and physiological effect under changing environment. The use of cultured specimens under well-controlled environmental conditions for geochemical studies will improve the application of environmental proxies, and will also be applicable for the estimation of carbon assimilation and physiological effect on calcification. In addition, micro-volume stable isotopic analysis will contribute to ensuring the reliability of international standard reference materials of carbonate and to promote high-resolution environmental reconstruction in collaboration with various research fields.

著者

吉村 寿紘

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.52, no.3, pp.131-142, 2018-09-25 (Released:2018-09-25)

参考文献数

59

---

Major cations (Na, Mg, K and Ca) are essential for life and play a major role in the global geochemical cycles. Dissolved cations in terrestrial waters derive from both silicate and carbonate rocks, and rivers and groundwater deliver them to the ocean, where there is a steady-state balance between inputs and outputs over geological time. Calcium carbonates are central components in understanding the chemical budgets of major cations for modern and past oceans. Biogenic CaCO3 is an important tool for elucidating the oceanic chemical evolution and past climate changes. Recent advances in mass spectroscopy techniques have made it possible to explore the stable isotope system of Mg, Ca, K and Sr in geologic materials, each of which are novel indicator for constraining the interplay of natural systems in the geological past; continental weathering, carbonate budgets, mid-ocean ridge spreading rates, etc.

著者

増田 彰正

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.37, no.1, pp.31-41, 2003-03-19 (Released:2017-01-12)

被引用文献数

1

著者

菅崎 良貴 村上 隆

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.51, no.2, pp.61-77, 2017-06-25 (Released:2017-06-25)

参考文献数

153

被引用文献数

1

---

Atmospheric oxygen evolution has long been discussed, especially with its relevance to the origin and evolution of life and the planet. Presence/absence of detrital redox-sensitive minerals, iron formations and red beds, behaviors of redox-sensitive elements in paleosols (ancient, subaerially-altered continental rocks) and ratios of carbon and sulfur stable isotopes in sedimentary rocks have been utilized to constrain atmospheric oxygen levels, which can dictate surface redox states, in the distant past, leading to a conventional view that the beginning (2.5–1.8 Ga) and ending (0.8–0.5 Ga) of the Proterozoic were two major periods when the oxygen level significantly increased in the Earth's history. More recent studies adopt multiple sulfur isotopes, iron speciation and trace elements (isotopes) as additional redox proxies. These proxies are not inconsistent with the conventional view, but the magnitude and timing of changes in these proxies are different between proxies and between geological records obtained from, e.g., iron formations, shales and paleosols. Also, the proxies suggest that there may have been transient oxygen increases of uncertain magnitude at 3.3–3.0 and 2.7–2.5 Ga. To better understand atmospheric oxygen evolution, process-based methods which quantify oxygen levels from individual proxies need to be developed to consistently and comprehensively explain multiple geochemical signatures.

著者

平賀 岳彦 渡部 泰史 宮崎 智詞

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.46, no.4, pp.231-242, 2012-12-31 (Released:2017-02-20)

参考文献数

39

被引用文献数

1

---

Investigation of intergranular regions of fine-grained metamorphic rocks using various electron microscopy reveals the presence of intergranular pores previously filled with an aqueous fluid. Such intergranular fluid inclusions exhibit a characteristic shape which minimizes interfacial energy at intergranular regions. The distribution of the inclusions indicates that they were formed from fluid filled intergranular microcracks that ovulated into inclusions due to the initially unstable form of a fluid film at grain boundaries. A simple calculation of interfacial stresses produced by anisotropic thermal contraction of quartz grains during cooling of the quartz aggregate demonstrates that most grain boundaries in crustal rocks experience intense intergranular cracking accompanied by infiltration of fluids. Presence of the fluid filled cracks might explain the observations of low electrical resistivity and seismic wave speeds at middle to shallow crustal depths. The inhibition of the crack formation due to the interfacial stress relaxation in ductile crustal regions results in higher electrical resistivity and seismic wave speeds at greater deep. Intergranular chemical components in mantle rocks are ubiquitously found in mantle xenoliths. We can attribute these components to intergranular melts which were present in the mantle.

著者

荒井 章司 阿部 なつ江 松本 一郎 三浦 真

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.55, no.1, pp.5-30, 2021-03-25 (Released:2021-03-25)

参考文献数

146

---

Chromitites (chromite ores) are reviewed for their importance in magmatism, hydrothermalism, geodynamics and production of resources. The key process for chromitite production is possibly the formation of magmas oversaturated with chromite (or chromian spinel).Production of relatively silica-rich magma during the formation of dunite envelope is coupled with the production of the podiform chromitite. The origin of stratiform chromitites is challenged based on a new idea on the origin of chromite-hosted mineral inclusions, commonly found in all types of chromitites. The chromite-hosted melt inclusions, now characterized by the assemblage pargasite+aspidolite+orthopyroxene, are possibly formed during reaction melting of orthopyroxene within the mantle. Chromite grains in the crustal stratiform chromitites, at least in part, are produced in the mantle stage and transported upward to the magma chamber. Origin of ultrahigh-pressure chromitites has been highly debated, but is still enigmatic. Chromitites of hydrothermal origin have been found and may contribute to redistribution of Cr both in the mantle and in the crust. Production of chromitite ores in Japan is also reviewed. Chromitites serve as a good petrologic marker in both mantle and crustal rocks, and will greatly contribute to our understanding of deep-seated structure and mantle processes in the mantle drilling.

著者

石橋 純一郎

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.51, no.3, pp.103-118, 2017-09-25 (Released:2017-09-28)

参考文献数

90

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A seafloor hydrothermal fluid circulation system develops beneath the seafloor where a magma as heat source and fault systems as fluid conduits are equipped. Seafloor hydrothermal systems act as important intermedia among the lithosphere, hydrosphere and biosphere. Seawater entrained into the seafloor evolves to the vent fluid that exit smokers or chimneys, through the processes during the fluid circulation such as elemental exchanges by water-rock interactions and involvement of magmatic volatiles. These interactions cause hydrothermal alteration of the lithosphere, looking from the opposite perspective. Chemical species dissolved in the vent fluids provide energy sources for biosphere around and beneath the seafloor of hydrothermal fields. Geochemical flux transported into the deep ocean by hydrothermal plumes affects chemical and biological processes in the hydrosphere. Formation of mineral deposits from the hydrothermal fluids leads concentration of specific metal elements resulting from long duration of hydrothermal activity. As hydrothermal vent sites have been discovered ubiquitously in various geologic settings, their diversity especially in geochemical aspects becomes more noticeable and interesting.

著者

野崎 達生 加藤 泰浩 鈴木 勝彦

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.4, pp.279-305, 2014-12-25 (Released:2015-01-06)

参考文献数

132

被引用文献数

1

---

Along with the progresses in analytical procedure and mass spectrometry, the number of papers using a Re–Os isotope system has rapidly increased, although Re and Os are trace elements whose typical concentrations in geological materials are ppt~ppb levels. Rhenium has two isotopes and 187Re is a radio isotope which generates 187Os through β- decay in the half-life of 41.6 Gyr. Since both Re and Os are highly siderophile and chalcophile elements, they are concentrated into sulfide minerals. Besides the 187Re–187Os decay system, Re is more incompatible than Os during a magma differentiation process, producing a large variety of the 187Re/188Os and 187Os/188Os ratios among various reservoirs on the Earth. The seawater 187Os/188Os ratio is mainly controlled by riverine flux having a high 187Os/188Os ratio (~1.4) and hydrothermal fluid/cosmic dust fluxes with low values (0.12~0.13). Thus, the Re–Os isotope system is a powerful tool for (1) geochronology of sulfide deposit, black shale and petroleum deposit using an isochron method, (2) geochronology of ferromanganese crust whose sedimentary age can be determined by fitting their 187Os/188Os ratios with the secular variation curve of the marine Os-isotope ratio, (3) decoding the trigger and processes of global climate change and impact event, and (4) unraveling the magma source and formation processes of volcanic rocks. Here, we review the recent geochemical study using the Re–Os isotope system and especially focus on a geochronology of the sulfide deposit.

著者

野津 憲治

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.19, no.1-2, pp.71-84, 1985-10-15 (Released:2016-11-26)

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Four topics on "Geochemistry of the crust and mantle" are reviewed. The contents are as follows. 1. Introduction 2. Abundances of the elements (2.1) Crustal abundances (2.2) Chemical composition of the earth (2.3) Cosmic abundances 3. Age determination 4. Partition of the elements (4.1) MASUDA-CORYELL plot: Partition of rare earth elements (4.2) ONUMA diagram: Crystal structure control of the element distribution between solid and liquid phases (4.3) Intracrystalline exchange equilibrium 5. Evolution of the crust and mantle, and mantle heterogeneity (5.1) MASUDA-MATSUI model (5.2) Isotopic evolution model of the crust and mantle (5.3) Layered mantle model and mantle heterogeneity 6. Epilogue

著者

小路 翔子 笹木 康平 上田 晃 中本 利正

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.50, no.2, pp.97-114, 2016

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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 <i>ca</i>. 1 km. The total geothermal resources in the study area are estimated to be <i>ca</i>. 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

安川 和孝 中村 謙太郎 藤永 公一郎 岩森 光 加藤 泰浩

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.52, no.4, pp.171-210, 2018-12-25 (Released:2018-12-25)

参考文献数

130

被引用文献数

2

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Since the discovery of rare-earth elements and yttrium (REY)-rich mud in the Pacific Ocean, a variety of research has been conducted to understand its spatial distribution and genesis. In this paper, we review the latest research outcomes on REY-rich mud, including the discovery of “extremely REY-rich mud” containing >5,000 ppm of total REY, a promising deep-sea mineral resource in Japan’s exclusive economic zone surrounding Minamitorishima Island. Then, we introduce a new statistical approach based on independent component analysis (ICA) to clarify the origin of REY-rich mud in the Pacific and Indian oceans, with a theoretical background and a protocol of ICA application on geochemical data. Independent components extracted from a multi-elemental dataset of ~4,000 samples demonstrate distinctive geochemical features, and their spatiotemporal distributions indicate that the sedimentation rate is an underlying key factor for REY-enrichment. We also refer to an important link between the genesis of REY-rich mud and Earth system dynamics. Finally, we focus on some challenges to be overcome. One of the most significant questions concerns the formation mechanism of the extremely REY-rich mud. An important key to this question is the depositional age of the extraordinary sediment layer.

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

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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

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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_CO2 of spring waters is 10^-2.3 to 10^1.1 atm. These high P_CO2 are probably caused by a large supply and fast decomposition of litter, owing to the climatic characteristics of the island. High concentrations of Ca²⁺ and HCO₃^- in spring waters may be caused by the reaction of limestone with CO₂. High concentrations of SO₄^2-, HCO₃^- and excess Na⁺ (Na⁺ of non sea water origin) are found in spring waters from the southern area. These Ca-SO₄・HCO₃ 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 NO₃^--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 δ¹⁸O 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-8δ¹⁸O) 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

松本 英二

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.17, no.1, pp.27-32, 1983

被引用文献数

13

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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

篠原 隆一郎 古里 栄一

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.51, no.4, pp.159-170, 2017-12-25 (Released:2017-12-25)

参考文献数

56

被引用文献数

6

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Phosphorus (P) is one of the most important nutrients for all living organisms. Recently, not only inorganic P but also organic P has been focused because of the development of an analytical technique— 31P nuclear magnetic resonance (NMR) spectroscopy. In the current paper, we reviewed historical backgrounds of the P analysis with the reason for using NMR and the limitation. Furthermore, we discussed the processes of sediment and suspended particles in lakes in the recent studies. The processes are complex, including physical, chemical, and biological aspects (i.e. diffusion, resuspension, adsorption/desorption, and enzymatic hydrolysis). Because P is present majorly as particulate forms, it is affected by physical processes compared with carbon and nitrogen. We shed light on how the processes of physical, chemical, and biological aspects affect P behavior in sediment and suspended particles in shallow and deep lakes.

著者

三宅 泰雄 島田 利夫 川村 清 重原 好次

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.Special, pp.131-135, 1975-03-30 (Released:2016-11-07)

著者

中尾 淳

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.55, no.4, pp.96-109, 2021-12-25 (Released:2021-12-25)

参考文献数

105

被引用文献数

3

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Selective adsorption at the frayed edge site (FES) of micaceous minerals is the most important reactions controlling soil-to-plant transfer of radiocesium. In this article, radiocesium adsorption on soils and minerals are reviewed, especially focusing on the wide differences in the amount or effectiveness of the FES between soils. Micaceous mineral contents in parent materials primarily control the FES in soils. Whereas granitoids and shales typically contains biotite and illite, respectively, other rocks may have developed to FES-poor soils unless eolian dusts had been deposited from continental desert areas. Weathering of micaceous minerals into vermiculite increases the FES content. However, large portion of the FES could be inaccessible for radiocesium in soil environments, either through the mineral coverage with humic substances or hydroxy-Al polymers interlayering. Thus, soil formation processes are important to understand how soils obtained the ability to retain radiocesium.