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Miyakawa, Kazuya; Kashiwaya, Koki*; Komura, Yuto*; Nakata, Kotaro*
Geochemical Journal, 57(5), p.155 - 175, 2023/00
Times Cited Count：0 Percentile：0.01(Geochemistry & Geophysics)In the thick marine sediments, groundwater altered from seawater during the burial diagenesis may exist. Such altered ancient seawater will be called fossil seawater. In such a field, groundwater flow is considered extremely slow because it is not affected by the seepage of meteoric water even after the uplift. During diagenesis, dehydration from silicates causes changes such as a decrease in the salinity of the porewater. However, dehydration reactions alone cannot quantitatively explain water chemistry changes. In this study, we developed an analytical model that considers the dehydration reaction from silicates during the burial process and the upward migration of porewater due to compaction and examined the possible evolution of porewater chemistry. The results showed that the water chemistry, which was strongly influenced by the dehydration reaction from opal-A to quartz and from smectite, was similar to the observations from boring surveys. The results suggest that the fossil seawater formed during the diagenesis may have been preserved since the uplift and strongly supports the slow groundwater flow in the area where the fossil seawater exists.
Nara, Fumiko*; Yokoyama, Tatsunori; Yamasaki, Shinichi*; Minami, Masayo*; Asahara, Yoshihiro*; Watanabe, Takahiro; Yamada, Kazuyoshi*; Tsuchiya, Noriyoshi*; Yasuda, Yoshinori*
Geochemical Journal, 55(3), p.117 - 133, 2021/00
Times Cited Count：6 Percentile：57.32(Geochemistry & Geophysics)The absolute date of the Millennium Eruption (ME) of Changbaishan Volcano is widely recognized as AD 946. The Baegdosan-Tomakomai (B-Tm) tephra dispersed during the ME is a robust-age key bed. In order to identify the tephra, refractive index and major-element compositions of volcanic glass shards are conventionally used. However, trace-element analysis has been rarely carried out, especially for rare-earth elements (REEs) and for tephra layer bulk sediments. Here we present the datasets of major- and trace-element compositions datasets for the glass shards and bulk sediments of the B-Tm and Towada caldera eruptions (To-a) tephra deposits from the Lake Ogawara sediment core, Tohoku region, northern Japan. The depth profiles of the major and trace elements show the significant peaks for the K
O and some trace elements (Zn, Rb, Zr, Nb, Sn, Y, La, Ce, Nd, Th, and U) at the B-Tm tephra layer in the Lake Ogawara sediment core, but no peaks of these elements at the To-a tephra layer. High concentrations of the trace elements in the B-Tm tephra layer were observed in individual glass shards as well as in the bulk sediment. These concentrations are highlighted by the elemental abundance pattern normalized by the crustal abundance. The elemental pattern in individual glass shards from other Japanese tephras showed significant differences from those of the B-Tm tephra, especially in REEs compositions. The trace-element compositions of the glass shards and bulk sediment show strong advantages for distinguishing the B-Tm tephra from other Japanese tephras.
Watanabe, Takahiro; Tsuchiya, Noriyoshi*; Kitamura, Akihisa*; Yamasaki, Shinichi*; Nara, Fumiko*
Geochemical Journal, 55(6), p.325 - 340, 2021/00
Times Cited Count：3 Percentile：32.31(Geochemistry & Geophysics)Geochemical signatures of natural samples could be an effective proxy to identify paleo tsunami deposits. However, less geochemical approach has been applied in the Pacific coast of middle Japan. Therefore, geochemical characteristics of the paleo tsunami deposits were studied using geological samples from the Shizuoka plain in the Pacific coast of middle Japan, and this paper shows the first geochemical dataset of paleo tsunami deposits from the area. In this study, typical geochemical biplots and ternary diagrams were applied to discriminate the paleo tsunami deposits from other layers. Additionally, vertical and horizontal distributions of titanium normalized values and statistical methods of geochemical data could provide the information for characteristic of the deposits to detect prehistorical tsunami inundation.
Watanabe, Takahiro; Fujita, Natsuko; Matsubara, Akihiro; Miyake, Masayasu*; Nishio, Tomohiro*; Ishizaka, Chika; Kokubu, Yoko
Geochemical Journal, 55(4), p.277 - 281, 2021/00
Times Cited Count：2 Percentile：21.91(Geochemistry & Geophysics)Small-mass radiocarbon dating less than 0.1 mg carbon has been developed by Accelerator mass spectrometry (AMS) and manual preparation techniques using the vacuum glass lines. Because geological samples are limited for the dating in many cases, preparation techniques should be improved for small samples and high efficiency analysis. For radiocarbon dating of geological and other organic samples, small-mass graphitization of international standard reference materials (ca. 0.1 and 0.05 mg carbon) was evaluated using the elemental analyzer and automated graphitization equipment 3 (EA-AGE3; IonPlus AG) in our study. Additionally, this paper presents the first data for the small samples by the EA-AGE3. The average radiocarbon concentration of the small-mass international standards (NIST-SRM4990C, IAEA-C5, and C7) prepared by the EA-AGE3 were agreement with the consensus values within 
2
. Therefore, small-mass graphitization using the EA-AGE3 can be adapted for AMS radiocarbon measurements in our case (down to ca. 0.05 mg carbon).
-edge XANES to determination of U oxidation state in zirconTanaka, Kazuya; Takahashi, Yoshio*
Geochemical Journal, 53(5), p.329 - 331, 2019/00
Times Cited Count：0 Percentile：0.01(Geochemistry & Geophysics)We examined three natural zircon samples with different amounts of radiation doses using M-edge and L
-edge U X-ray absorption near-edge structure (XANES). Analysis of XANES spectra at both M-edge and L-edge suggested that the oxidation state of U in the zircon sample with the highest radiation dose is tetravalent. The XANES spectra of the two other samples with lower radiation doses suggested a mixture of U(IV) and U(VI), while the possibility of U(V) was not excluded. This is the first work on the application of M-edge U XANES to the oxidation state of U in natural zircon.
Yokoyama, Tatsunori; Kimura, Junichi*; Mitsuguchi, Takehiro; Danhara, Toru*; Hirata, Takafumi*; Sakata, Shuhei*; Iwano, Hideki*; Maruyama, Seiji*; Chang, Q.*; Miyazaki, Takashi*; et al.
Geochemical Journal, 52(6), p.531 - 540, 2018/12
Times Cited Count：17 Percentile：65.79(Geochemistry & Geophysics)Sasamoto, Hiroshi; Sato, Hisao*; Arthur, R. C.*
Journal of Geochemical Exploration, 188, p.318 - 325, 2018/05
Times Cited Count：3 Percentile：16.65(Geochemistry & Geophysics)Ammonium is potentially an important constituent of deep groundwater under reducing condition. The retention of cesium by sorption in geological formations may have an important role ensuring the long-term safety of high-level radioactive waste. Cesium sorption will be affected by competing effects due to dissolve cation likely ammonium in groundwater, however. In the present study, a possible reaction to control of ammonium in deep groundwater was evaluated based on the data selected in the Horonobe as a test case in Japan. Results of investigation of mineralogy, thermodynamic evaluation of groundwaters and the Electron Probe Micro Analysis (EPMA) to identify nitrogen distribution on minerals suggest that the clay minerals bearing potassium, particularly smectite, illite and interstratified illite/smectite, appear to control the ammonium concentration in groundwaters by ion exchange reactions. Additionally, the selected groundwaters in the Horonobe seem to resemble to the gas and oil fields groundwater in the screened dataset in Japan in terms of ammonium distribution.
Cs activity concentrations in sediment collected off the coast of Fukushima Prefecture in 2013-2015Fukuda, Miho*; Aono, Tatsuo*; Yamazaki, Shinnosuke*; Ishimaru, Takashi*; Kanda, Jota*; Nishikawa, Jun*; Otosaka, Shigeyoshi
Geochemical Journal, 52(2), p.201 - 209, 2018/00
Times Cited Count：3 Percentile：16.65(Geochemistry & Geophysics)To elucidate recent activity levels and the behavior of radiocesium in the coast off Fukushima Prefecture, lateral and vertical distributions of Cs in sediment were observed in 2013-2015 at 12 monitoring stations. At stations around the water depth of 100 m, relatively higher Cs activities were observed from surface sedimentary layer (0-3 cm). In these stations, sediments had high content of silt to clay particles and organic matter. The high Cs activities in the surface sediments were attributed to accumulation of highly mobile sediment particles. In October 2014, at some coastal stations, sharp peaks of Cs activities were observed in the subsurface (5-16 cm) sediments, whereas such broad peaks were not found in October 2015. These results suggest that the Cs activities in sediment had largely changed by lateral transport and re-sedimentation on the surface, as well as sediment mixing in the middle-layers.
Tanaka, Kazuya; Watanabe, Naoko*; Yamasaki, Shinya*; Sakaguchi, Aya*; Fan, Q.*; Takahashi, Yoshio*
Geochemical Journal, 52(2), p.173 - 185, 2018/00
Times Cited Count：9 Percentile：43.3(Geochemistry & Geophysics)We analyzed riverbed sediments collected at two sites, Yamakiya and Kuroiwa, in Fukushima after the Fukushima accident. The size distributions of K, Rb, and 
Csreflected the mineralogy of sediments, where primary host minerals for these alkali elements would be biotite, K-feldspar, and clay minerals. Silt-size fractions contained high Cs and 
Cs concentrations possibly due to adsorption on clay minerals. Their concentrations decreased with particle size at the Yamakiya site. In contrast, coarse and very coarse sand fractions from the Kuroiwa site showed higher Cs and Cs concentrations in comparison to fine - medium sand fractions. The coarse sand fractions contained many weathered biotite grains. Overall, the size distributions of Cs and Cs were similar in the sediments, suggesting that the Fukushima-derived radiocesium was distributed into each particle size fraction in response to the distribution of the stable Cs that was controlled by mineralogical composition.
Sakaguchi, Aya*; Chiga, Haruka*; Tanaka, Kazuya; Tsuruta, Haruo*; Takahashi, Yoshio*
Geochemical Journal, 52(2), p.187 - 199, 2018/00
Times Cited Count：7 Percentile：35.55(Geochemistry & Geophysics)An aerosol sample collected on the 15th of March 2011 at Kawasaki City (Kanagawa) was sequentially leached with seawater for 30 days. As a result, about 60% of the total Cs was extracted. In addition, a surface soil sample collected from Kawamata Town (Fukushima) two months after the Fukushima accident, was leached for 223 days with a natural seawater, a 1:1 mixture of ultrapure water and seawater, and ultrapure water. Eventually, more than 15% of the total Cs in the surface soil sample was efficiently desorbed by seawater leaching. In comparison, about 9% of the total Cs was leached with 1:1 diluted seawater and less than 1% of the total Cs was leached with ultrapure water over the 223 days. Overall, Cs and Cs showed similar leaching behaviour.
) of radiocesium in the Kuchibuto River in FukushimaMiura, Hikaru*; Kurihara, Yuichi*; Sakaguchi, Aya*; Tanaka, Kazuya; Yamaguchi, Noriko*; Higaki, Shogo*; Takahashi, Yoshio*
Geochemical Journal, 52(2), p.145 - 154, 2018/00
Times Cited Count：48 Percentile：93.68(Geochemistry & Geophysics)Solid-water distribution coefficient () of radiocesium in rivers is apparently increased due to the possible presence of highly radioactive radiocesium-bearing microparticles (CsMPs) in the solid phase. In this study, we evaluated the contribution of CsMPs to apparent Kd values. The ratio of the radioactivity of the separated CsMPs to the total radiocesium on fluvial suspended particles ranged from 0 to 46%. This means that the existence of CsMPs in fluvial suspended partcles did not change apparent Kd values in order magnitude.
Satou, Yukihiko; Sueki, Keisuke*; Sasa, Kimikazu*; Yoshikawa, Hideki; Nakama, Shigeo; Minowa, Haruka*; Abe, Yoshinari*; Nakai, Izumi*; Ono, Takahiro*; Adachi, Koji*; et al.
Geochemical Journal, 52(2), p.137 - 143, 2018/00
Times Cited Count：68 Percentile：97.15(Geochemistry & Geophysics)Yamaguchi, Akiko*; Honda, Tasuku*; Tanaka, Masato*; Tanaka, Kazuya; Takahashi, Yoshio*
Geochemical Journal, 52(5), p.415 - 425, 2018/00
Times Cited Count：18 Percentile：61.41(Geochemistry & Geophysics)Ion-adsorption type REE deposits in weathered granite are main sources of REE essential for high-technology industries. However, these type deposits have not been searched in Japan. In this study, Bulk REE abundances (= REE
), ion-exchangeable REE (= REE
) by ammonium chloride solution, and percentage of REE relative to REE (= REE
) in fresh and weathered granite samples in Southwest Japan (i.e., Hiroshima and Shimane Prefectures) were determined. The REE and REE were comparable to those of ion-adsorption type REE deposits in China. Extended X-ray adsorption fine structure (EXAFS) spectra of REE in original samples and samples after the extraction of ion-exchangeable REE showed that (i) REE in samples with high REE mainly forms outer-sphere complexes and (ii) the remaining REE in the rocks after the extraction forms inter-sphere complexes.
Nakada, Ryoichi*; Takahashi, Yoshio*; Zheng, G.*; Yamamoto, Yuhei; Shimizu, Hiroshi*
Geochemical Journal, 44(5), p.411 - 418, 2010/10
Times Cited Count：27 Percentile：58.17(Geochemistry & Geophysics)Patterns of the entire range of REE in crude oils and coexisting water, collected from mud volcanoes in Xinjiang Province of China, are reported here for the first time. Crude oils show light REE enriched patterns with flat or depleted patterns in heavy REE, when normalized to chondrite. The REE concentrations in crude oils are larger than those in coexisting water by a factor of more than one hundred. Considering the hydrophobicity of oil and the high ionic characteristics of REE, it is strongly suggested that REE form complexes with ligands present in the crude oils. Based on the 
C NMR spectroscopy, it is found that small amounts of phenol and carboxyl groups are contained in the crude oil samples, which could possibly provide complexing sites for REE. REE patterns of crude oils are similar to those of coexisting mud samples collected from the same mud volcanoes, which suggests that the REE in crude oils are derived from rocks and sediments where crude oils were generated.
Osawa, Takahito; Hatsukawa, Yuichi; Nagao, Keisuke*; Koizumi, Mitsuo; Oshima, Masumi; Toh, Yosuke; Kimura, Atsushi; Furutaka, Kazuyoshi
Geochemical Journal, 43(6), p.415 - 422, 2009/00
Times Cited Count：4 Percentile：16.49(Geochemistry & Geophysics)The Cretaceous-Tertiary (K-T) boundary about 65 million years ago records a mass extinction event caused by a bolide impact. K-T boundary clay collected from Stevns Klint, Denmark was investigated in this work. Iridium concentrations of eight clays across the K-T boundary were determined using a multiple 
-ray analysis system after neutron activation. Anomalously high Ir concentrations were detected in five marl samples, with the highest concentration being 29.9 ppb. Four samples were analyzed for all noble gases. No extraterrestrial Ar, Kr, and Xe were discovered in any of the samples, although most of the 
He which was detected was extraterrestrial. Solar-like Ne was observed only in the sample SK4, which had an Ir concentration of 14.3 ppb, indicating the presence of micrometeorites.
Yoshida, Yasushi*; Yoshikawa, Hideki; Nakanishi, Takashi*
Geochemical Journal, 42(3), p.295 - 304, 2008/00
Times Cited Count：15 Percentile：37.78(Geochemistry & Geophysics)Partition coefficients (
) of Ra and Ba in calcite were derived in an experiment of coprecipitation. Free Drift Method (FDM) was adopted. As a result of experiment, of Ra and Ba were 9.4e-3 and 4.7e-3, respectively. A saturation state is expected to be a low oversaturation in duration of experiment and according to an estimated saturation index, a composition of a final solution was close to equilibrium with calcite. The values of 
and 
showed the similar extent. It implies that difference of size of ionic radius does not affect incorporation behavior of Ra and Ba in calcite.
Manaka, Mitsuo*; Yanase, Nobuyuki; Sato, Tsutomu*; Fukushi, Keisuke*
Geochemical Journal, 41(1), p.17 - 27, 2007/00
Times Cited Count：29 Percentile：56.2(Geochemistry & Geophysics)Natural attenuation was investigated for the antimony in the drainage water of an abandoned mine. Drainage water, waste rocks, and ocherous precipitates collected from the mine were investigated in terms of their mineralogy and chemistry. The chemistry of the drainage water was analyzed by measuring pH, ORP, and EC on site as well as by ICP-MS and ion chromatography. The results of these investigations indicated that Sb, which is generated by the dissolution of stibnite (SbS
) and secondary formed Sb minerals in waste rocks, was attenuated by iron-bearing ocherous precipitates, especially schwertmannite, that form over time in the drainage water. Bulk distribution coefficients (Kd) for this Sb adsorption to the precipitates ranges up to at least 10
L/kg.
Fu, F.; Akagi, Tasuku*; Suzuki, Yuichiro*; Watanabe, Kazuo; Yabuki, Sadayo*
Geochemical Journal, 38(4), p.333 - 343, 2004/08
Times Cited Count：9 Percentile：20.33(Geochemistry & Geophysics)no abstracts in English
Yui, Mikazu; Sasamoto, Hiroshi; Arthur, R. C,*
Geochemical Journal, 38(1), p.33 - 42, 2004/00
Times Cited Count：10 Percentile：21.97(Geochemistry & Geophysics)None
Nagano, Tetsushi; Sato, Tsutomu*; Williams, I. S.*; Zaw, M.*; Payne, T. E.*; Airey, P. L.*; Yanase, Nobuyuki; Isobe, Hiroshi*; Onuki, Toshihiko
Geochemical Journal, 34(5), p.349 - 358, 2000/10
Times Cited Count：4 Percentile：13.58(Geochemistry & Geophysics)no abstracts in English
