著者

Nobuki Takamatsu Masayuki Imahashi Kyoko Kamimura Makoto Tsutsumi

出版者

GEOCHEMICAL SOCIETY OF JAPAN

雑誌

GEOCHEMICAL JOURNAL (ISSN:00167002)

巻号頁・発行日

vol.20, no.3, pp.143-151, 1986-06-20 (Released:2008-04-08)

参考文献数

27

被引用文献数

3 8

---

Lithium as well as major chemical constituents, and stable hydrogen and oxygen isotopic ratios in 30 saline spring waters (Cl>5, 000 mg/l) in Japan were determined to clarify the genesis of the waters. The relationship between log (Na/Li) and the temperature estimated by geothermometers revealed that the lithium content of saline spring waters are not usually controlled at the present-day temperatures of the hydrothermal systems. Taking into account the values of the deviation coefficient of lithium to seawater, CLi = (Li/Cl) sample/(Li/Cl) seawater, and the regions from which the spring waters were collected, the spring waters can be classified into the following four groups: Group 1, representing saline waters from coastal line (CLi = 1.2–22), Group 2 those from greentuff region (CLi = 17–110), Group 3 those from Osaka Basin (CLi = 160–220), and Group 4 those from the outer part of Median Tectonic Line (CLi = 250–440). The genetic features of the respective groups are discussed in detail.

著者

Sebastian Oscar Danielache Chisato Yoshikawa Mizuo Kajino Satoshi Itou Wataru Kakeya Naohiro Yoshida Yasuhito Igarashi

出版者

GEOCHEMICAL SOCIETY OF JAPAN

雑誌

GEOCHEMICAL JOURNAL (ISSN:00167002)

巻号頁・発行日

vol.53, no.2, pp.103-118, 2019 (Released:2019-04-05)

参考文献数

24

被引用文献数

1

---

We present a numerical study conducted using a regional Lagrangian model to account for the transport, deposition and radioactive decay of 35S in sulfur dioxide and sulfate aerosols emitted into the atmosphere during the Fukushima Dai-ichi Nuclear Power Plant incident. The model is a Eulerian-Lagrangian hybrid system that accounts for chemical conversion of SO2 into SO42− in a Eulerian manner. The simulations were compared to field measurements of atmospheric 35S in sulfate collected at Kawamata, Tsukuba, Kashiwa, Fuchu and Yokohama, Japan. The 35S emission scenario that best replicated the field measurements followed the same temporal variation pattern as the 134/137Cs emissions. These results suggest that 35S and 134/137Cs follow a similar release pattern. Among the considered emission scenarios, a maximum flux of emitted chemical compounds was assumed to be either 100% 35SO42− or 100% 35SO2, with values of 4.0 × 1019 molecules/hour and 4.0 × 1020 molecules/hour, respectively on March 14th. These emission scenarios reflect the findings reported in the literature, where traces of 35SO2 were measured along with 35SO42−, so the actual emission is expected to be a combination of both chemical forms. The Kawamata measurements (Figs. 5 and 6) presented a large concentration in the July–August period, several months after emissions decreased by more than an order of magnitude. To explain this anomaly, re-suspension ratios were calculated for the Kawamata site, which ranged between 0.1 and 1.5% and partially, but not fully, explain the large measured concentrations. Furthermore, they show large discrepancies with 134/137Cs re-suspension values for measurements at the town of Namie. This situation indicates a lack of understanding of the transformations of 35S that occurs after deposition and the mechanisms involved in the 35S re-suspension process.

著者

Lin-gun Liu

出版者

GEOCHEMICAL SOCIETY OF JAPAN

雑誌

GEOCHEMICAL JOURNAL (ISSN:00167002)

巻号頁・発行日

vol.16, no.4, pp.179-198, 1982 (Released:2008-04-08)

参考文献数

52

被引用文献数

1

---

The distribution of chemical elements in the Earth's crust and its inferred interior is controlled mainly by the density periodicity of the elements, and is further perturbed by chemical affinity of the elements. The chemical elements have been classified into four major groups: heavy, medial, light and volatile, according to the physical and chemical properties and the distribution pattern of the elements. The light elements are generally enriched in the Earth's surface and the heavy elements are concentrated in its center. The abundances of most of the heavy and light elements increase and decrease respectively, very rapidly with increasing depth, whereas those for the medial and volatile elements remain relatively uniform throughout the Earth (except the core). Chemical affinity controls the abundances of the volatile and medial elements more than those of the light and heavy elements. On the basis of the principles of elemental distribution observed in the Earth, it is deduced that the chondrites were formed in an enviornment which experienced little gravitational influence, whereas the achondrites were formed under the influence of gravitation. The distribution of chemical elements in the Sun does not appear to be influenced by its gravitational field, which might be a consequence of nuclear fusion processes.

著者

Hidekazu Yoshida Koshi Yamamoto Toshiaki Ohe Nagayoshi Katsuta Yusuke Muramiya Richard Metcalfe

出版者

GEOCHEMICAL SOCIETY OF JAPAN

雑誌

GEOCHEMICAL JOURNAL (ISSN:00167002)

巻号頁・発行日

vol.54, no.4, pp.233-242, 2020 (Released:2020-08-27)

参考文献数

35

被引用文献数

7

---

Spherical carbonate concretions are commonly observed in marine clayey sedimentary strata and often contain well preserved fossils. Previous studies revealed that the spherical concretions are formed by the very rapid reaction with decomposed organic matter from inside and Ca2+ ion of seawater. However, the detailed mass transport process during concretion formation has not been completely understood. Here two different size of spherical concretions, cm size of tusk-shell concretions and metre size of Moeraki boulders, are re-examined to understand the diffusion oriented formation process. Field observations, and detailed mineralogical (XRD) and geochemical analyses (SXAM, XRF, δ13C) revealed diffusive transport of HCO3− from decaying organic matter and Ca2+ from surrounding pore-water of marine origin led to solid carbonate precipitation reactions that progressed from the margin of a concretion. Based on the compositional gradients across the concretions, a diffusion based diagram has been applied to estimate the growth rates of the different size of spherical concretions. The process and rate estimation indicate that even gigantic spherical concretions can form quite rapidly in the muddy matrices under a diffusion-controlled transport regime.

著者

Gil Michard Anton Stettler Christian Fouillac Gérald Ouzounian Dominique Mandeville

出版者

GEOCHEMICAL SOCIETY OF JAPAN

雑誌

GEOCHEMICAL JOURNAL (ISSN:00167002)

巻号頁・発行日

vol.10, no.3, pp.155-161, 1976-09-20 (Released:2008-04-08)

参考文献数

15

被引用文献数

13 26

---

The chemical analyses of the mineral waters issuing in the basin of Vichy St Yorre provide the means to decipher different subsuperficial modifications superposed on the fluid originating at great depths: (1) Increasing amounts of dissolved Ca, Sr, Mg and sometimes K, by gradual attack of shallow host rocks. (2) Precipitation of silica and associated aluminium. (3) Mixing with fresh surface waters. The comprehensive study of these alterations allows to shed light on the initial composition of deep water. From the silica content, the Na/K ratio and the calcite saturation, a temperature of 135°C is inferred for this water.

著者

Kazuhiro Suzuki Mamoru Adachi

出版者

GEOCHEMICAL SOCIETY OF JAPAN

雑誌

GEOCHEMICAL JOURNAL (ISSN:00167002)

巻号頁・発行日

vol.25, no.5, pp.357-376, 1991 (Released:2008-04-08)

参考文献数

42

被引用文献数

145 260

---

Precise electron microprobe analysis makes it possible to determine the Th, U and Pb concentrations in an area less than 5 μm across in a single grain of monazite, zircon or xenotime; the detection limit of PbO at 2σ confidence level is 0.005–0.008 wt.% and the relative error is 3% for 0.2 wt.% concentration level. The subgrain analyses of monazite are plotted on the coordinates of PbO and ThO2* (ThO2 plus the equivalent of UO2), and those of zircon and xenotime on the coordinates of PbO and UO2* (UO2 plus the equivalent of ThO2). Data points are arrayed linearly and enable us to define an isochron which passes through the origin. The chemical Th-U-total Pb isochron ages coincide well with mineral and whole-rock ages isotopically determined for the same samples. The chemical Th-U-total Pb isochron method was applied to the age determination of monazite, zircon and xenotime from the Tsubonosawa paragneiss and the host Hikami granite in the South Kitakami terrane of Northeast Japan. The chemical ages show that (1) the sedimentation of the gneiss-protolith occurred soon after the emplacement of 500 Ma granitoids in the source region, where the 500 Ma granitoids were widespread together with Precambrian rocks possibly dated back to as old as Archean (3080 ± 180 Ma), (2) the gneiss-protolith was metamorphosed to the amphibolite facies grade about 430 ± 10 Ma ago, and (3) the gneiss was affected by multiple thermal events of 350, 260, 180 and 100 Ma. The 350 Ma event corresponds to the intrusion of the Hikami granite, and the 100 Ma one to the intrusion of the Cretaceous Kesengawa granite. The 260 and 180 Ma events may correspond in age to the main metamorphic event and subsequent igneous activity in the Hida terrane, central Japan. The chemical Th-U-total Pb isochron age in terms of the precise microprobe analysis of low-level Th, U and Pb will open a new vista on the Paleozoic-Mesozoic tectonics of the Japanese Islands.

著者

Iwao Kawabe

出版者

GEOCHEMICAL SOCIETY OF JAPAN

雑誌

GEOCHEMICAL JOURNAL (ISSN:00167002)

巻号頁・発行日

vol.29, no.4, pp.213-230, 1995-08-20 (Released:2008-04-08)

参考文献数

42

被引用文献数

23 42

---

All fourteen REE and Y have been determined for eight GSJ reference rocks including granitic and rhyolitic samples by ICP-AES with a preconcentration method. The two rhyolites (JR-1 and JR-2) and one granite (JG-2) exhibit convex tetrad effects of the M-type even in their chondrite-normalized REE patterns. Their tetrad effects, however, are modified from ideal ones by some step-like variations in their abundances from Tm to Lu. Similar step-like irregularities are seen commonly in chondrite-normalized patterns of other samples: granodiorites (JG-1, JG-1a, and JG-3), a fresh water lake sediment (JLk-1), and an alkali basalt (JB-1). We normalized the REE analyses for JR-1, JR-2, and JG-2 by those for JB-1, and then found that they clearly indicate quite regular convex tetrad effects of the M-type without apparent irregularities in heavy REE. The other samples, when similarly normalized by JB-1, also display analogous but less marked convex tetrad effects except for JG-3. Our present results are strong evidence for the tetrad effect in magmatic processes relevant to granitic and rhyolitic rocks formations. There are common chemical characteristics among JG-2, JR-1, and JR-2: (1) large negative Eu anomalies, and (2) rather high F contents of about 1, 000 ppm. The chemical characteristics and the theoretical basis of tetrad effects may suggest that the granitic and rhyolitic rocks with the convex tetrad effects of the M-type are residual silicate melts having partitioned REE with fluids in late stages of differentiation processes. The basalt-normalization appears to be so effective for extracting tetrad effects of granitic and rhyolitic rocks. It filters off the REE characteristics common in magmatic products like the step-like irregularities in heavy REE abundances when normalized by chondrite. This makes it easier to identify lanthanide tetrad effects in magmatic rocks.

著者

NAOTO HIRANO

出版者

GEOCHEMICAL SOCIETY OF JAPAN

雑誌

GEOCHEMICAL JOURNAL (ISSN:00167002)

巻号頁・発行日

vol.45, no.2, pp.157-167, 2011-04-20 (Released:2013-11-01)

参考文献数

63

被引用文献数

1 43

---

One extremely young volcano (0.05–1 Ma) and other young volcanoes (1.8, 4.2, 6.0, and 8.5 Ma) composed of strongly alkaline magma were recently discovered on the abyssal plain of the Early Cretaceous (135 Ma) Pacific Plate. These volcanoes were dubbed “petit-spots”. The petit-spot volcanic province represents more than 8 Myr of activity over a large area (~600 km along the direction of plate motion), but with a relatively small volume of magma production, thus indicating a small supply of heat inconsistent with a hotspot. The low-flux petit-spot volcanoes may be related to the occurrence of a tensional field of lithosphere caused by plate flexure, with the ascending melt derived from a mantle source susceptible to partial melting. Rock samples from the young volcanoes are highly vesicular (up to 60%) despite high hydrostatic pressures at 6000 m water depth, indicating volatile-rich magmas. The depleted heavy rare earth elements and high radiometric isotopic ratios of noble gases indicate the magma was derived from upper mantle. Nevertheless, the low 143Nd/144Nd, high 87Sr/86Sr, low 206Pb/204Pb, and low 207Pb/204Pb ratios are similar to enriched or fertile compositions such as oceanic island basalts. These apparently conflicting data are explained by the extremely small degree of partial melting of recycled materials in the degassing mantle of the asthenosphere, probably with carbonate in the source. The petit-spot volcanoes, therefore, provide a unique window into the nature of the oceanic plate and underlying asthenosphere prior to subduction.

著者

Yoji Arakawa Xiaolin Li Mitsuru Ebihara Engin Meriç Izavel Tansel Simau Bargu Hayrettin Koral Kuniteru Matsumaru

出版者

GEOCHEMICAL SOCIETY OF JAPAN

雑誌

GEOCHEMICAL JOURNAL (ISSN:00167002)

巻号頁・発行日

vol.37, no.6, pp.681-693, 2003-12-20 (Released:2008-04-08)

参考文献数

42

被引用文献数

2 2

---

Some element concentrations were measured and element profiles were made for the Cretaceous-Tertiary (K-T) boundary layers in Medetli, Gölpazari, northwestern Turkey. In Medetli region, gray-colored medium to coarse grained sandstone (layer A) is overlain by yellow-colored fine-grained sandstone with intercalated thin goethite-rich layers (layer B). White colored limestone (layer C) overlies on the layer B. The layer A is latest Cretaceous and layer C is early Paleocene, and in layer B (28–37 cm in thickness) fossils are absent, and is regarded as a K-T transitional layer. In several goethite-rich layers, siderophile elements such as Fe, Cr, Ni, Co, and chalcophile element, such as As, Sb, and Zn, are enriched, and have maximum in succession from layer A to C. The enrichment of these elements are common features in most of K-T boundary sediments of the world. However, Ir concentration is relatively low (0.05–0.10 ppb) in the goethite-rich layers. The analyzed Ir concentration is slightly elevated (0.24 ppb) only in the top part of layer A. Iridium may have been diluted during sedimentation and diagenesis. The actual K-T boundary may be situated between the top of layer A and the bottom of layer B. The section from the top part of layer A to layer B is assumed to have been formed during the K-T and its successive events.

著者

P. K. Kuroda John C. H. Liou Ashok D. Banavali John D. Akridge Larry A. Burchfield

出版者

GEOCHEMICAL SOCIETY OF JAPAN

雑誌

GEOCHEMICAL JOURNAL (ISSN:00167002)

巻号頁・発行日

vol.18, no.2, pp.55-60, 1984-04-20 (Released:2008-04-08)

参考文献数

14

被引用文献数

2 6

---

The amount of excess 210Po activity injected into the atmosphere by the 18 May 1980 eruption of Mount St. Helens was greater than that of 90Sr released by the 16 October 1980 Chinese test explosion of a 0.2 to 1 megaton nuclear device. The occurrence of a ‘mystery’ cloud prior to the 28 March 1982 eruption of El Chichón volcano was accompanied by an increase in the 210Po/210Pb ratio in rain samples collected at Fayetteville, Arkansas, during the months of January and February, 1982.

著者

MASAHIRO SAKATA MASAHIRO NATSUMI YUKINORI TANI

出版者

GEOCHEMICAL SOCIETY OF JAPAN

雑誌

GEOCHEMICAL JOURNAL (ISSN:00167002)

巻号頁・発行日

vol.44, no.2, pp.113-123, 2010-04-20 (Released:2013-03-23)

参考文献数

34

被引用文献数

11

---

The boron concentration and isotopic composition (δ11B) of precipitation collected from December 2002 to March 2006 at three sites on the Japan Sea coast were measured. Those sites have been considerably affected by the long-range transport of air pollutants from the Asian continent during winter and spring when the airflows from the Asian continent are predominant. The boron concentration in the precipitation increased primarily during winter whereas the δ11B decreased during winter or spring. It is assumed that this decrease in δ11B is not associated with a Rayleigh distillation process, because the previous δD values of the precipitation collected at a site on the Japan Sea coast did not decrease in the same manner. A weak correlation (r2 = 0.13-0.24, P 11B and the nonsea-salt sulfate (nss-SO42-)/B ratio at each site, suggesting that boron in the precipitation originate primarily from two sources. The first source, which is characterized by high δ11B and nss-SO42-/B = 0, is seawater. At the northern site, the enrichment factor for boron in the precipitation relative to seawater approached unity during winter. This implies that much of the boron in the precipitation is derived from unfractionated sea salts rather than gaseous boron evaporated from seawater. The second source is characterized by low δ11B and high nss-SO42-/B ratio. Most of the nss-SO42- in the precipitation originates from anthropogenic combustion activities in the Asian continent based on the previous model calculations. Coal accounts for a major portion of the total primary energy supply in China. Moreover, coal enriches boron and represents generally negative δ11B values. Hence, we propose that the emission of boron from coal burning is the most likely second source. Thus, boron isotopes may be useful as tracers of coal-burning plumes from the Asian continent.

著者

A. Kracher G. Kurat V. F. Buchwald

出版者

GEOCHEMICAL SOCIETY OF JAPAN

雑誌

GEOCHEMICAL JOURNAL (ISSN:00167002)

巻号頁・発行日

vol.11, no.4, pp.207-217, 1977-12-20 (Released:2008-04-08)

参考文献数

40

被引用文献数

14 41

---

A study of accessory minerals in the Cape York iron meteorite has been carried out with the electron microprobe. Phases analyzed include chromite, sphalerite, two closely related potassium-bearing sulfides, silica, and native copper. In addition, four phosphate minerals were found: One chemically similar to buchwaldite, but rather rich in iron, one corresponding to terrestrial maricite, and two more, which seem to be new minerals on the basis of microprobe analysis. Evidence from the composition of accessory minerals as well as texture elucidates some details of the fractional crystallization of the group III AB parent melt. A modification of the fractional crystallization model is therefore proposed. We suggest that sulfide nodules have originated as droplets of an immiscible sulfur-rich liquid that continuously segregated from the parent melt during crystallization of the metal. The modified model also explains the Ni/Cr anticorrelation and the high abundance of sulfur in group III AB irons which could not be satisfactorily explained by previous models.

著者

ZHONGHUAN XIA BAIQING XU INES MÜGLER GUANGJIAN WU GERD GLEIXNER DIRK SACHSE LIPING ZHU

出版者

GEOCHEMICAL SOCIETY OF JAPAN

雑誌

GEOCHEMICAL JOURNAL (ISSN:00167002)

巻号頁・発行日

vol.43, no.4, pp.275-286, 2009-08-20 (Released:2011-04-19)

参考文献数

55

---

この論文は撤回されました。

著者

YASUTAKA TERAKADO YUKO OFUKA NOZOMI TADA

出版者

GEOCHEMICAL SOCIETY OF JAPAN

雑誌

GEOCHEMICAL JOURNAL (ISSN:00167002)

巻号頁・発行日

vol.44, no.4, pp.315-322, 2010-08-20 (Released:2013-03-23)

参考文献数

44

被引用文献数

10

---

Rare earth elements (REE), Sr, Ba, Fe, Mg, Ca, Na, and K concentrations in three kinds of living foraminiferal tests collected from Iriomote Island, Japan were measured in order to obtain some qualitative aspects of trace element behavior during biogenic CaCO3 formation. The obtained results were examined using the sample/seawater concentration ratios, which can be considered as a measure of total effect of element incorporation into biogenic CaCO3 in marine environments. On a sample/seawater concentration ratio vs. ionic radius diagram, the foraminifera/seawater ratios of trivalent REEs and divalent Mg, Ca and Sr fall on their respective curves having peaks near the Ca ionic radius. This is consistent with the most widely accepted theory that solid/liquid partition coefficients are largely controlled by the sizes of the host site in the crystal and the substituting cation, such that a cation that has the most suitable size for the site can enter the crystal most easily. On the other hand, the foraminifera/seawater ratios of Fe and Ba show higher values than those expected from the crystal structure control model, which might be caused by insoluble precipitates such as Fe-hydroxides and barite. It is interesting that the concentrations of REEs in foraminifera are correlated with those of Fe, which suggests coprecipitation of REE with Fe-hydroxide. Such coprecipitation of REE might have occurred in seawater, followed by uptake of Fe-hydroxides by foraminiferal food micro-organisms. After digestion of such food, the dissolved REEs in intracellular fluid might have fractionated as CaCO3 crystallization proceeds, and the combined crystal structure and ionic radius effect becomes conspicuous forming a peak on the foraminifera/seawater ratio vs. ionic radius diagram.

著者

Isoji Miyagi Osamu Matsubaya Satoru Nakashima

出版者

GEOCHEMICAL SOCIETY OF JAPAN

雑誌

GEOCHEMICAL JOURNAL (ISSN:00167002)

巻号頁・発行日

vol.32, no.1, pp.33-48, 1998-02-20 (Released:2008-04-08)

参考文献数

55

被引用文献数

17 25

---

The hydrogen isotopic composition of hornblende in volcanic rocks has potential to indicate processes such as degassing of a magma reservoir, as well as the origin of magmatic water. However, during eruption and high-temperature interaction with air, the isotope composition of hornblende can be altered. In order to establish criteria to select natural hornblende that preserves magmatic hydrogen isotopic ratios, hydrogen isotopic composition (δD), water contents, and colors of hornblendes were measured. A series of heating experiments on natural green hornblendes was conducted in air and under vacuum up to 1000°C. There observed a negative relationship between the intensity of redness (a∗) and water content among heated hornblendes in air and under vacuum, as well as natural samples from several Quaternary volcanos in Japan. Heating hornblende results in a significant increase in δD value that can be explained by a Rayleigh distillation (simultaneous degassing without hydrogen isotopic exchange between the gas and the mineral) model involving degassing of both H2O and H2. According to the model, maximum fractionation occurs when hornblende dehydrates only by H2 degassing. Application of the model indicates that hornblendes in pumice fragments from Plinian eruptions are most representative of the δD of pre-eruptive magma. In contrast, the δD values of minerals from lava flows, lava domes, or even from thick pumice flow deposits may have suffered from 1) hydrogen isotopic fractionation by mineral dehydration, and/or 2) isotopic re-equilibration with degassing magma during eruption stage and during cooling stage after the emplacement.

著者

OHNO TAKESHI MURAMATSU YASUYUKI MIURA YOSHINORI ODA KAZUMASA INAGAWA NAOYA OGAWA HIROMU YAMAZAKI ATSUKO TOYAMA CHIAKI SATO MUTSUTO

出版者

GEOCHEMICAL SOCIETY OF JAPAN

雑誌

GEOCHEMICAL JOURNAL (ISSN:00167002)

巻号頁・発行日

vol.46, no.4, pp.287-295, 2012

被引用文献数

74

---

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, <i>n</i> = 5), 522 ± 80 (SD, <i>n</i> = 5), and 608 ± 79 (SD, <i>n</i> = 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.

著者

KYOKO MASUKAWA YOSHIRO NISHIO KEN-ICHIRO HAYASHI

出版者

GEOCHEMICAL SOCIETY OF JAPAN

雑誌

GEOCHEMICAL JOURNAL (ISSN:00167002)

巻号頁・発行日

vol.47, no.3, pp.309-319, 2013-06-20 (Released:2013-11-26)

参考文献数

43

被引用文献数

10

---

Ore-forming fluid trapped in vein quartz as fluid inclusions from tungsten ore at the Takatori mine was extracted by a crush-leach technique. The trace metal content and isotopic composition (δ7Li and 87Sr/86Sr ratio) of inclusion fluids were measured. Although quartz single crystals can host fluid inclusions associated with different generations, careful selection of analytical samples made it possible to separate the temporal mineralization stages. We succeeded in reconstructing the evolution of the ore-forming fluid from the results of chemical analyses. δ7Li values of the ore-forming fluid were between -2.6 and +7.9‰, gradually increasing in the later stages. The early-stage fluid characterized by low δ7Li values was derived from magma with a meta-sedimentary source (S-type granite). During precipitation of Li-bearing minerals, the δ7Li value of the ore-forming fluid became larger. The initial 87Sr/86Sr ratio of early-stage ore-forming fluid was 0.7202 to 0.7276, suggesting that the fluid responsible for tungsten mineralization was derived from S-type magma, and this magma had a different origin from the granitic rocks widely distributed in the mining area.

著者

TAKASHI TOMIYASU MASAYUKI EGUCHI HAYAO SAKAMOTO KATSURO ANAZAWA RYUSUKE IMURA

出版者

GEOCHEMICAL SOCIETY OF JAPAN

雑誌

GEOCHEMICAL JOURNAL (ISSN:00167002)

巻号頁・発行日

vol.40, no.3, pp.253-263, 2006 (Released:2007-06-22)

参考文献数

21

被引用文献数

3 11

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The atmospheric concentration of mercury was determined daily for 3 years (July 1999-March 2002) in Kagoshima City to clarify the seasonal variation of mercury levels and the influence of mercury emitted from Sakurajima. The atmospheric mercury was collected on a porous gold collector at Kagoshima University approximately 11 km west of Sakurajima and the amount of mercury was determined by cold vapor atomic absorption spectrometry (CVAAS). A loss of temperature dependency was found for the east wind in 1999. However, in 2001, high temperature dependency was observed for all wind directions with the easing of volcanic activity. Short-term movement in the atmospheric concentration of mercury was also investigated by making measurements every two hours over a three-day period at heights of 3 and 12 m. This operation was carried out about every two months in the year 2001 at Kagoshima University. The atmospheric mercury concentration was higher in the daytime than nighttime showing temperature dependency: the concentration at 3 m (Hg(3m)) ranged from 1.65 to 17.9 ng m-3 (5.96 ± 3.47 ng m-3) in the daytime and 1.50 to 12.8 ng m-3 (4.20 ± 2.33 ng m-3) overnight, while that at 12 m (Hg(12m)) ranged from 1.24 to 29.4 ng m-3 (4.74 ± 3.61 ng m-3) and 1.38 to 14.8 ng m-3 (4.50 ± 2.85 ng m-3), respectively. The variation in Hg(3m) from day to night was considerably larger than that in Hg(12m). As a result, Hg(3m) was higher than Hg(12m) in the daytime and lower in the nighttime. On the other hand, the concentration gradient showed a high degree of dependency on solar radiation. These observations suggested that mercury is emitted from the ground with an increase in solar radiation and rise of the temperature in the daytime and deposits with the fall of temperature at nighttime. The influence of rain and volcanic activity on the periodic variation of mercury is also discussed in detail.

著者

YASUTO MIYAKE HIROYUKI MATSUZAKI TAKESHI FUJIWARA TAKUMI SAITO TAKEYASU YAMAGATA MAKI HONDA YASUYUKI MURAMATSU

出版者

GEOCHEMICAL SOCIETY OF JAPAN

雑誌

GEOCHEMICAL JOURNAL (ISSN:00167002)

巻号頁・発行日

vol.46, no.4, pp.327-333, 2012-08-20 (Released:2013-11-08)

参考文献数

28

被引用文献数

1 92

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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.

著者

M. YAMAMOTO T. TAKADA S. NAGAO T. KOIKE K. SHIMADA M. HOSHI K. ZHUMADILOV T. SHIMA M. FUKUOKA T. IMANAKA S. ENDO A. SAKAGUCHI S. KIMURA

出版者

GEOCHEMICAL SOCIETY OF JAPAN

雑誌

GEOCHEMICAL JOURNAL (ISSN:00167002)

巻号頁・発行日

vol.46, no.4, pp.341-353, 2012-08-20 (Released:2013-11-08)

参考文献数

11

被引用文献数

59 24

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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.