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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.
Takahashi, Hiroshi*; Minami, Masayo*; Aramaki, Takafumi*; Handa, Hiroko*; Kokubu, Yoko; Ito, Shigeru*; Kumamoto, Yuichiro*
Radiocarbon, 61(6), p.1879 - 1887, 2019/12
Times Cited Count：2 Percentile：11.66(Geochemistry & Geophysics)Water sample for interlaboratory comparison (here after "comparison water") must have inalterable 
C concentration during the comparison campaign and inter-batches homogeneity. In this study, the procedure for preparing of comparison water was discussed. We employed that comparison waters were artificially made by mixing chemical reagents, controlling C concentration and chemical composition. We could prepare six comparison waters, having 1, 14, 37, 56, 72 and 100 pMC, respectively. The stable carbon isotopic values and chemical compositions of some batches were measured to exanimate the inter- batches homogeneity. The C discrepancies among the batches were negligible for the inter-laboratory comparison. Finally, the results of trial comparison in Japan will be presented. Most of C results of CO extracted by six laboratories showed good agreements each other.
Be concentrations in bed-sediments of Ado and Yasu rivers flowing into Lake BiwaFujisawa, Jumpei*; Minami, Masayo*; Kokubu, Yoko; Matsuzaki, Hiroyuki*
JAEA-Conf 2018-002, p.91 - 94, 2019/02
Beryllium-10 (Be) of a cosmogenic nuclide precipitates in forms of BeO and Be(OH) attaching with aerosol on the Earth surface. It is accumulated on the sea- and lake-bottoms. Recently, the meteoric Be is attracting attention as a powerful tool for investigating the past climate change, because it is affected by the earth- and lorcal- cyclical changes of materials such as atmosphere and water circulation. The Be exists mostly as hydroxide at pH 
5, and is easy to adhere to soil and mineral surface. Therefore, Be concentration in sediment could be influenced by its grain size composition because fine-grained sediment has a big surface area per unit mass. The purpose of this study is to reveal the relationship between Be concentrations and the grain-size of river sediments. The samples used were bottom-sediments of 18 rivers flowing into Lake Biwa, Japan. The sediments were sieved to 5 fractions and analyzed each for Be concentration by JAEA-AMS-TONO.
Minami, Masayo*; Takahashi, Hiroshi*; Aramaki, Takafumi*; Kokubu, Yoko; Ito, Shigeru*; Nakamura, Toshio*
Nagoya Daigaku Kasokuki Shitsuryo Bunsekikei Gyoseki Hokokusho, 26, p.132 - 137, 2015/03
We have started a Radiocarbon Intercomparison on Chemical Experiments, Water series (RICE-W) program to examine whether carbon isotopic fractionation and carbon contamination occur or not on C analysis of dissolved inorganic carbon (DIC) in water by different sample preparation and storage methods. Eight water samples of four kinds (surface seawater, ground water, hot spring water, and sodium bicarbonate solution) have already analyzed by six AMS laboratories in Japan, and the results obtained are gradually being published. Here, we report the progress of RICE-W program briefly, and then give consideration to the result using the precipitation method, by which DIC is precipitated into SrCO
or BaCO, and then oxidized with HPO
to extract CO.
Yoshida, Hidekazu*; Metcalfe, R.*; Ishibashi, Masayuki; Minami, Masayo*
Geofluids, 13(1), p.45 - 55, 2013/02
Times Cited Count：14 Percentile：55.31(Geochemistry & Geophysics)In granitic rocks fracture networks provide pathways for groundwater flow and solute transport that need to be understood to assess the long-term performance of deep underground environment. In order to clarify the long-term processes, Japanese plutons of different ages were studied. Detailed investigation of in-situ fracture fillings sampled from a depth of 300 meters was carried out to clarify the fracturing and mineral infilling processes. Different plutons show identical episodes, consisting of: brittle tensile fracturing (Stage I); relatively rapid uplifting accompanied by hydrothermal water circulation that produced fracture fillings (Stage II); and a period of low-temperature meteoric water circulation (Stage III). The paragenesis of carbon isotopic compositions of carbonate minerals show that there were distinct episodes of mineral precipitation. The evolution of fillings identified here enable development of a model of fracturing and persistence of fluid conducting systems.
Minami, Masayo*; Takahashi, Hiroshi*; Aramaki, Takafumi*; Kokubu, Yoko; Ito, Shigeru*; Wada, Hideki*; Nakamura, Toshio*
no journal, ,
We generally use some sample preparation methods for radiocarbon analysis of dissolved inorganic carbon (DIC) in water samples; the precipitation method, the bubbling method and the headspace-extraction method. These sample preparation methods have good and bad points each. Therefore, we have initiated a Radiocarbon Intercomparison on Chemical Experiments, Water series (RICE-W) program in Japan to examine whether the CO extraction procedures of water DIC introduce carbon isotopic fractionation and carbon contamination. Eight water samples for four kinds of surface seawater, ground water, hot spring water, and sodium bicarbonate solution have already provided to six AMS laboratories in Japan and are being carried out comparison of C measurements. We show the result of the RICE-W program in this presentation.
from Noto peninsular in Kanazawa, JapanYamada, Rena*; Ikemori, Fumikazu*; Nakamura, Toshio*; Minami, Masayo*; Watanabe, Takahiro; Kinouchi, Kento*; Matsuki, Atsushi*
no journal, ,
PM is becoming the focus of international attention, particularly in eastern Asia, because of air pollution and the health risks. Carbon is one of the major components in aerosol. Therefore, sources of the carbon compound should be known for the understanding material cycles and mechanism of the rise. Radiocarbon analysis is unique and useful techniques for estimation of carbon sources in environmental samples including aerosol. Hence half-life of radiocarbon is 5730 years, percent modern carbon (pMC) value based on radiocarbon concentration of fossil fuels are negligible. Therefore, pMC value can reveal the components of carbon in aerosol (biomass carbon versus fossil fuel). In this study, aerosol samples were taken at Noto Peninsula in Ishikawa pref., Japan, in order to estimate contribution rate of biomass carbon and/or fossil fuel in PM. The pMC values of PM at Noto were more than 70 in the summer of 2014. These results show that biomass contribution is relative high in the area.
at NOTO peninsula using C analysisYamada, Rena*; Ikemori, Fumikazu*; Nakamura, Toshio*; Minami, Masayo*; Watanabe, Takahiro; Kinouchi, Kento*; Matsuki, Atsushi*
no journal, ,
Aerosols and clouds seeded by them both affect the heat budget of the Earth, but their RF (radiative forcing) still involves large uncertainty (IPCC 2013). One of the least understood properties of aerosols is the source and contribution of the organics. Our recent observation revealed that submicron aerosol particles in Noto peninsula also have a relatively high concentration (approximately more than 50%) of carbonaceous matter throughout the year. It is difficult to presume its sources specifying its chemical species in many scenes because of its great variety. However, we can presume its source by using carbon isotope ratio. We conducted sampling in NOTOGRO (NOTO ground-based research observatory), lying at the edge of Noto peninsula, from 26th Jun to 23rd July, 2014. We corrected PM using high volume air sampler for every week. Flow rate was 700L/min, and quartz fiber filter was used for sampling. C was analyzed using AMS C system (High Voltage Engineering Europe, Model 4130-AMS) and 
C using IRMS (isotope ratio mass spectrometer) in Nagoya University. As a result, it was found that 4 samples collected from 26th Jun to 23rd July had approximately 70 percent modern carbon (pMC). This result shows that modern plant (and/or biomass burning) activities mainly contribute to the submicron organic particle concentration in Noto peninsula.
Be in bed-sediments of Ado and Yasu rivers flowing into Lake BiwaFujisawa, Jumpei*; Minami, Masayo*; Kokubu, Yoko
no journal, ,
To investigate grain size dependency on concentration of meteoric Be extracted from river bed-sediment, we analyzed the Be in bed-sediments of Yasu and Ado rivers flowing into Lake Biwa, Shiga Prefecture. Each of 5 grain size fractions was sequentially leached to extract Ex (Exchangeable), Am-Ox (amorphous oxy-hydroxide) and X-Ox (crystalline oxy-hydroxide) phases, respectively, and the Be concentrations of the leachates were measured. Most meteoric Be was located in the Am-Ox and X-Ox phases. The concentrations of bulk and extracted fractions decreased with increasing grain size. Furthermore, the bed-sediments from upper stream showed higher concentration than those from downstream, and this tendency was stronger in Yasu river than in Ado river. The difference between Yasu and Ado river sediments could be due to lower pH of water in Yasu river than in Ado river, that is, due to more partitioning of Be into water relative to sediment particles in Yasu river.
Yoshida, Hidekazu*; Yamamoto, Koshi*; Maruyama, Ippei*; Asahara, Yoshihiro*; Minami, Masayo*; Shirono, Shinichi*; Hasegawa, Hitoshi*; Katsuta, Nagayoshi*; Nishimoto, Shoji*; Muramiya, Yusuke*; et al.
no journal, ,
no abstracts in English
