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Iwatsuki, Teruki; Hayashida, Kazuki; Kato, Toshihiro; Munemoto, Takashi; Kubota, Mitsuru
no journal, ,
Redox change around drift and MIU facility were observed to estimate redox resilience of granitic rock for facility construction and operation. Redox potential in the vicinity of research gallery and MIU facility heterogeneously changed from -200 to -100 mV in two years according to geological structure.
Buesseler, K. O.*; German, C. R.*; Honda, Makio*; Otosaka, Shigeyoshi; Black, E. E.*; Kawakami, Hajime*; Manganini, S. M.*; Pike, S.*
no journal, ,
A three year time-series of particle fluxes is presented from sediment traps deployed at 500 and 1000 m at a site 115 km southeast of Fukushima Daiichi Nuclear Power Plant. Results show a high fraction of lithogenic material in sinking particles, suggesting a lateral source of sediments. From 
Cs/
Pb ratio in sinking particles, it was inferred that accident-derived radiocesium associate with slope and shelf sediments were resuspended and transported laterally to the offshore regions in winter and typhoon seasons. Continuous observation of such transport processes of particulate radiocesium near the seabed would be significant for better understanding of the fate of accident-derived radiocesium.
Yokoyama, Tatsunori; Kokubu, Yoko; Murakami, Hiroaki; Hirata, Takafumi*; Sakata, Shuhei*; Danhara, Toru*; Iwano, Hideki*; Chang, Q.*; Kimura, Junichi*
no journal, ,
The chronological information about carbonates is useful for modeling and enables forecast of geological and geochemical environmental changes by simulating. The U-Th-Pb dating method for carbonates which were formed at reducing environment remain to be established. The final goal of our study is to establish in situ U-Th-Pb dating method for carbonates which are filling cracks in pervious rock like fault rocks. In this study, the U-Th-Pb elemental and isotopic two-dimension distribution for an ammonite fossil were visualized by "Imaging" method using Laser-ablation ICP Mass Spectrometry. In U-Pb isotope analysis for carbonates in cracks of granites, we could not obtain significant U-Pb age data by the lack of uranium and influence of non-radiogenic common lead. When the concentration of lead is sufficiently high for the measurement, we obtained reliable isotopic data from carbonates and their lead isotopic composition reflected characteristic composition of their origin water.
Miwa, Kazuji; Obata, Hajime*; Suzuki, Takashi; Otosaka, Shigeyoshi
no journal, ,
I-129 in a global environment is originated from the European nuclear fuel reprocessing plants (NFRP), Sellafield in U.K. and La Hague in France, and it is observed a large amount of I-129 inflows from European NFRP into the eastern and central Arctic Ocean. Previous studies on I-129 at surface indicated seawater with high I-129 concentration does not inflow from eastern and central Arctic Ocean to Chukchi Sea, located in western Arctic Ocean. However, there is a possibility of inflow of I-129 because the vertical distribution of I-129 has not observed at the ocean. The purpose of this study is to identify the inflow of seawater with high I-129 concentration from eastern and central Arctic Ocean by observing the vertical distribution of I-129 and water mass structure in Chukchi Sea and Bering Sea. Seawater with high temperature at surface of southern Chukchi Sea (- 66
N) and with low temperature at bottom of the northern Chukchi Sea (69N -) were observed. The seawater with low temperature might include high I-129 concentration. However, I-129 concentration in some points was observed ranging from 0.79 to 2.89 (10
atoms/L), which was two orders of magnitude lower than that in the eastern and central Arctic Ocean. And no significant difference of I-129 concentration between seawater at surface and at bottom was shown. Therefore, we could not identify the inflow of seawater with high I-129 concentration from eastern and central Arctic Ocean to Chukchi Sea.
Malins, A.; Sakuma, Kazuyuki; Kurikami, Hiroshi; Machida, Masahiko; Kitamura, Akihiro
no journal, ,
Motokawa, Ryuhei; Endo, Hitoshi*; Yokoyama, Shingo*; Nishitsuji, Shotaro*; Yaita, Tsuyoshi; Kobayashi, Toru; Suzuki, Shinichi
no journal, ,
no abstracts in English
Kozai, Naofumi; Sakamoto, Fuminori; Onuki, Toshihiko; Sato, Takahiro; Koka, Masashi; Kamiya, Tomihiro; Esaka, Fumitaka
no journal, ,
To reveal the role of protozoa in environmental migration of radionuclides, this study investigated behavior of heavy elements (U, Eu) during culture of Paramecium sp. with yeast on which heavy elements were sorbed. Paramecium was chosen as model protozoa. After the exposure of yeast cells to a dilute heavy element aqueous solution, phosphates of these elements formed on yeast cells. Paramecium cells were cultured with those yeast cells. Only very small fractions of the presorbed heavy elements were dissolved from yeast cells during the Paramecium culture. As culture time advances, membranous precipitates formed which contained undigested and digested yeast cells and dense membranous organic substance filling gaps between those cells. In the precipitates many phosphate particles which size and morphology are similar to those on the yeast cells were observed. These results suggest that the immobilization effect of yeast cells for heavy elements was preserved in the prey-predator system.
Tanaka, Kazuya; Takahashi, Yoshio*
no journal, ,
Tree barks were collected in Fukushima. Stable Cs was adsorbed on the barks and measured using XAFS to investigate its adsorption structure. XAFS analysis indicated that Cs was adsorbed on the barks as a outer-sphere complex.