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Journal Articles

Quantitative micro-X-ray fluorescence scanning spectroscopy of wet sediment based on the X-ray absorption and emission theories; Its application to freshwater lake sedimentary sequences

Katsuta, Nagayoshi*; Takano, Masao*; Sano, Naomi; Tani, Yukinori*; Ochiai, Shinya*; Naito, Sayuri*; Murakami, Takuma*; Niwa, Masakazu; Kawakami, Shinichi*

Sedimentology, 66(6), p.2490 - 2510, 2019/10

 Times Cited Count:2 Percentile:39.34(Geology)

Micro-X-ray fluorescence (XRF) scanning spectroscopy of marine and lake sedimentary sequences can provide detailed paleoenvironmental records available through element intensities proxy data. However, problems for effects of interstitial pore water on the micro-XRF intensities have been pointed out so far because of direct measurement on the split wet sediment surfaces. In this study, new methods for the XRF corrections were developed by being considered with the micro-X-ray scanning spectroscopy.

Journal Articles

Hydrological and climate changes in southeast Siberia over the last 33 kyr

Katsuta, Nagayoshi*; Ikeda, Hisashi*; Shibata, Kenji*; Kokubu, Yoko; Murakami, Takuma*; Tani, Yukinori*; Takano, Masao*; Nakamura, Toshio*; Tanaka, Atsushi*; Naito, Sayuri*; et al.

Global and Planetary Change, 164, p.11 - 26, 2018/05

 Times Cited Count:6 Percentile:46.34(Geography, Physical)

Paleoenvironmental and paleoclimate changes in Siberia were reconstructed by continuous, high-resolution records of chemical compositions from a sediment core retrieved from the Buguldeika Saddle, Lake Baikal, dating back to the last 33 cal. ka BP. The Holocene climate followed by a shift at ca. 6.5 cal. ka BP toward warm and dry, suggesting that the climate system transition from the glacial to interglacial state occurred. In the last glacial period, the deposition of carbonate mud from the Primorsky Range was associated with Heinrich events (H3 and H1) and the Selenga River inflow was caused by meltwater of mountain glaciers in the Khamar-Daban Range. The anoxic bottom-water during Allerod-Younger Dryas was probably a result of weakened ventilation associated with reduced Selenga River inflow and microbial decomposition of organic matters from the Primorsky Range. The rapid decline in precipitation during the early Holocene may have been a response to the 8.2 ka cooling event.

Journal Articles

Retention of rare earth elements, thorium and uranium in sedimentary rocks; A Case study in the Horonobe area of Hokkaido, Japan

Murakami, Takuma; Sasamoto, Hiroshi; Mizuno, Takashi

Chikyu Kagaku, 50(4), p.299 - 317, 2016/12

Development of techniques for investigating the long-term migration of elements in deep underground is important with respect to safety assessment for the geological disposal of high-level radioactive waste. As one study of the migration of elements in deep underground, the distribution of REE, Th and U in sedimentary rock of Horonobe area in Hokkaido was investigated, and discussed whether the difference of hydrogeological structure and lithofacies influences on the distributions. As the results, it was considered that REE and Th were mainly retained in minerals originating from terrigenous clastic and secondary mineral occurred in early diagenesis, and their distributions were relatively homogenous in both the Koetoi and Wakkanai formations. Uranium was indicated to be maintained in the sedimentary rock until now after depositing in deep-sea sediment. It was considered that the U deposition was occurred by adsorption on organic matter and reductive precipitation with decomposition of organic matter. In addition, it was confirmed that the distributions of these elements were not influenced by the difference of hydrogeological and lithofacies.

Journal Articles

RCA/IAEA third external dosimetry intercomparisons in East Asia region

Yamamoto, Hideaki; Yoshizawa, Michio; Murakami, Hiroyuki; Momose, Takumaro*; Tsujimura, Norio*; Kanai, Katsuta*; Cruz-Suarez, R.*

Radiation Protection Dosimetry, 125(1-4), p.88 - 92, 2007/07

 Times Cited Count:0 Percentile:0.01(Environmental Sciences)

The purpose of this paper is to discuss the results of the third intercomparison exercise of external radiation dosimetry organized under the Regional Cooperative Agreement (RCA) in the East Asia region of the International Atomic Energy Agency (IAEA). Twenty five laboratories from 16 member states participated in the exercise. Japan Atomic Energy Research Institute (JAERI) and Japan Nuclear Cycle Development Institute (JNC) arranged the standard irradiation of the participants' dosimeters. The results of the measurements of the irradiated dosimeters for the determination of external doses were satisfactory for all participants, demonstrating good performance in their external dosimetry.

Oral presentation

IAEA/RCA personal dosimetry intercomparison in Asian and Pacific region during the years of 1990-2004

Tsujimura, Norio; Momose, Takumaro; Yoshizawa, Michio; Yamamoto, Hideaki; Cruz-Suarez, R.*; Murakami, Hiroyuki

no journal, , 

As one of the IAEA/RCA projects, three phases of personal dosimetry intercomparison programs had been conducted during the years of 1990 to 2004. The purpose of the program was to assess the ability of the personal dosimetry services in the RCA Member States and also to provide technical help in improving a performance of their dosimetry systems and in implementing the operational quantities recommended by ICRU. The purpose of this paper is to trace the history of and to present a summarized review of the results of the intercomparison programs. The trend of the phase-by-phase results showed that the quality of individual monitoring in most of the Member States has become dramatically improved to an acceptable level. There was a successful achievement and advancement over the 15 years effort.

Oral presentation

Coordination of radiation cntrol practices in JAEA

Uezu, Yasuhiro; Tobita, Kazunori; Yamaguchi, Takenori; Momose, Takumaro; Murakami, Hiroyuki; Furuta, Sadaaki; Yamaguchi, Yasuhiro

no journal, , 

JAEA was established on October 1st, 2005 by integrating the Japan Atomic Energy Research Institute and the Japan Nuclear Cycle Development Institute. In these institutes, there were a several radiation control methods or original radiation control levels. After establishing JAEA, in order to make a harmonization of radiation control methods and levels, applications of these are investigated under actual situations.

Oral presentation

Natural analogue study based on chemical composition of the deep boreholes in Horonobe, Hokkaido.

Murakami, Takuma; Mizuno, Takashi

no journal, , 

no abstracts in English

Oral presentation

Behavior of REEs, U and Th in sedimentary rock of Horonobe, Hokkaido, Japan

Murakami, Takuma; Mizuno, Takashi

no journal, , 

no abstracts in English

Oral presentation

Hydrochemical study at the Horonobe Underground Research Laboratory

Mizuno, Takashi; Nanjo, Isao; Yamamoto, Nobuyuki; Miyakawa, Kazuya; Murakami, Takuma

no journal, , 

This study aimed to understand the hydrochemical evolution process at Horonobe area, northern Hokkaido Japan, based on chemical tracers. In this study, existing data was used for the estimation. As the result, it is revealed that the resolution of gas hydrate and the diffusion of porewater from upper strata to lower strata is important factor of hydrochemical evolution.

Oral presentation

The REE pattern in carbonate minerals obtained from sedimentary rocks in Horonobe, Hokkaido

Murakami, Takuma; Mizuno, Takashi; Sasamoto, Hiroshi; Kokami, Takayuki*; Sasaki, Takayuki*

no journal, , 

no abstracts in English

Oral presentation

Continental response to millennial-scale climate change during the last glacial to Holocene period

Ikeda, Hisashi*; Shibata, Kenji; Murakami, Takuma; Kokubu, Yoko; Katsuta, Nagayoshi*

no journal, , 

no abstracts in English

Oral presentation

Late Holocene environmental changes in west Mongolia revealed by the lacustrine sediment analyses

Hayakawa, Tsubasa*; Katsuta, Nagayoshi*; Kokubu, Yoko; Hasebe, Noriko*; Murakami, Takuma; Miyata, Yoshiki*; Hasegawa, Hitoshi*; Nagao, Seiya*; Kawakami, Shinichi*

no journal, , 

no abstracts in English

Oral presentation

Isolation and characterization of a novel fermentative bacterium in the phylum Bacteroidetes from a deep subsurface diatomaceous mudstone formation

Tamazawa, Satoshi*; Ueno, Akio*; Tamaki, Hideyuki*; Tamamura, Shuji*; Murakami, Takuma*; Kiyama, Tamotsu*; Inomata, Hidenori*; Miyakawa, Kazuya; Naganuma, Takeshi*; Kaneko, Katsuhiko*

no journal, , 

no abstracts in English

Oral presentation

Characterization of a novel fermentative iron-reducing Bacteroidetes bacterium isolated from deep subsurface diatomaceous mudstone formation

Tamazawa, Satoshi*; Ueno, Akio*; Tamaki, Hideyuki*; Tamamura, Shuji*; Murakami, Takuma*; Kiyama, Tamotsu*; Inomata, Hidenori*; Miyakawa, Kazuya; Naganuma, Takeshi*; Kaneko, Katsuhiko*

no journal, , 

no abstracts in English

Oral presentation

Outline of research on the safety of radioactive waste disposal; Study on the performance assessment of engineered barriers and the judgment criteria on borehole closure

Sawaguchi, Takuma; Abe, Takeyasu; Sasagawa, Tsuyoshi; Murakami, Hiroaki; Takeuchi, Ryuji; Iida, Yoshihisa; Takeda, Seiji

no journal, , 

no abstracts in English

Oral presentation

Analysis of microbial community structure in deep underground diatomaceous/siliceous mudstone formations and factors determining microbial community structure

Tamazawa, Satoshi*; Ueno, Akio*; Murakami, Takuma*; Miyakawa, Kazuya; Tamamura, Shuji*; Kiyama, Tamotsu*; Inomata, Hidenori*; Naganuma, Takeshi*; Kaneko, Katsuhiko*; Igarashi, Toshifumi*

no journal, , 

no abstracts in English

16 (Records 1-16 displayed on this page)
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