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Kokubu, Yoko; Matsushi, Yuki*; Ishizaka, Chika*; Hirao, Noriaki*; Yonaga, Yusuke; Yoshikawa, Kiyotaka*
JAEA-Testing 2019-002, 101 Pages, 2019/11
This report provides a description of sample preparation method for measurement of in-situ belliyum-10 (Be) and allumium-26 (Al) in terrestrial quartz using accelerator mass spectrometry at Tono Geoscience Center, Japan Atomic Energy Agency. The report is based on the laboratory manual "Chemistry for in-situ Be and Al measurement for terrestrial quartz by AMS at MALT ver.1.3 and ver.2.2" prepared by ph.D Matsushi at Kyoto University.
Pachri, H.*; Mitani, Yasuhiro*; Ikemi, Hiroaki*; Nakanishi, Ryunosuke*; Kokubu, Yoko
Journal of Geological Resource and Engineering, 3(4), p.163 - 172, 2015/09
Recently, the contributions of slope failures have been difficult to quantify over the time scales of the sediment concentrations in Sangun catchment area, Fukuoka Prefecture. This paper describes how cosmogenic nuclide methods have provided information about the geomorphic process by utilizing Be. The Be/Be ratios were measured by AMS. We assume that the cosmogenic nuclide concentrations stored in the sediment of a river can increase or decrease, depending on the amount of mixing of sediments during transport through the fluvial system. As results, the Be concentrations have been calculated to determine the short term sediment mixing rate in the catchment area. Therefore, the relationship between the morphometrics of the drainage basin, the sediment concentration by Be analysis and the contribution of landslides to landscape changes over timescales of several years have been investigated in Sangun catchment area.
Ikemi, Hiroaki*; Pachri, H.*; Kokubu, Yoko; Mitani, Yasuhiro*; Kuroki, Takahito*
no journal, ,
One of issues in the comprehensive river-sediment management is to develop how to estimate a sediment production from a mountainous stream. In this study, beryllium isotopes of quartz extracted from sediment samples have been analyzed by JAEA-AMS-TONO to clarify a sediment dynamics in mountain streams. The sediment samples have been collected at four riverbeds and one hillslope in two different sub-catchments (A and B) of a Mesozoic granitic block located in the Umi-kawa river basin, Fukuoka. The sample of the catchment B shows a little bit higher value in Be-content than those of catchment A. This result indicates that the river sediment in the catchment B includes quartz grains that have been exposed on a ground surface for a long time compared with the catchment A. It is also possible that the river sediment in the catchments A contains more landslide materials because the landslide materials, which have come from a deeper part, might have a lower value in Be-content.
Fujisawa, 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.