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H and CFCs concentrationsIwatsuki, Teruki; Omori, Kazuaki; Hagiwara, Hiroki; Hasegawa, Takuma*; Nakata, Kotaro*
no journal, ,
Appricability of tritium and CFCs as an tracer of shallow water infiltration into deep was evaluated at Mizunami underground reserach laboratory. The observation results show that the infiltration of shallow water increases with time. Especially CFCs is avairable tracer for groundwater with the residence time of several tens years.
reduction at deep granitic aquifer by anaerobic and high pressure culture experimentHirota, Akinari*; Togo, Yoko*; Fukuda, Akari*; Ito, Kazumasa*; Suzuki, Yohei*; Tsunogai, Urumu*; Komatsu, Daiyu*; Iwatsuki, Teruki
no journal, ,
Microbial activity in deep groundwater at Mizunami URL was estimated based on isotopic composition. The result shows that sulfate reduction activity is higher at low-H gas condition.
Saito, Takumi; Terashima, Motoki
no journal, ,
no abstracts in English
Hamamoto, Takafumi*; Saito, Takumi; Mizuno, Takashi; Tanaka, Satoru*
no journal, ,
no abstracts in English
concentration in groundwaterSasamoto, Hiroshi
no journal, ,
Cs has been considered as an important radionuclide for performance assessment of high-level radioactive waste disposal. It is expected that migration of Cs in rock would be retared by sorption on clay minerals. Sorption of Cs on clay minerals, however, might compete with other cations such as NH and K in groundwater. Therefore, it would be quite important to estimate the reaction controlling the NH concentration in groundwater for evaluation of Cs migration in rock. In the present study, thermodynamic calculations were conducted to estimate the reaction controlling the NH concentration in the Horonobe groundwaters. As the results, the Horonobe groundwaters were plotted on the mineral stability field of muscovite similar to illite which was dominant clay mineral in the Horonobe sedimentary rocks, and additionally an activity ratios of Hfor NH and K for groundwaters were plotted on the line of slope 1. These results suggest that the NH concentration in the Horonobe groundwaters could be controlled by an ion exchange reaction between NH and K on illite in the sedimentary rocks.
Otosaka, Shigeyoshi; Sato, Yuhi; Suzuki, Takashi; Narita, Hisashi*
no journal, ,
A sediment trap experiment was conducted between August 2011 and July 2013 and sinking particles were collected at 100 km east of the Fukushima Daiichi Nuclear Power Plant. Sinking flux of 
Cs was the highest in September 2011 (98 mBq/m
/day), and decreased over time with seasonal fluctuation. The sinking fluxes of particulate radiocesium were controlled by two modes. One was a rapid sinking of radiocesium-bound particles (summer mode). This mode was dominant especially in the early post-accident stage, and was presumed to establish the distribution of radiocesium in the offshore seabed. Another was the secondary transport of particles attributed to turbulence near the seabed and was observed in winter (winter mode). Although the latter process would not change the distribution of sedimentary radiocesium drastically, attention should be paid as a key process redistributing the accident-derived radiocesium over a long duration.
Miyakawa, Kazuya; Mizuno, Takashi; Hirota, Akinari*; Komatsu, Daisuke*; Tsunogai, Urumu*
no journal, ,
no abstracts in English
Murakami, Takuma; Mizuno, Takashi; Sasamoto, Hiroshi; Kokami, Takayuki*; Sasaki, Takayuki*
no journal, ,
no abstracts in English
Iwatsuki, Teruki; Saegusa, Hiromitsu; Onoe, Hironori
no journal, ,
Hydroceochemical change around Mizunami and Horonobe URLs were observed to understand hydrogeochemical impact caused by large-scale underground facility. The results show the change of groundwater pH, redox condition and the processes in excavation damage / disturbed zones.
Oda, Yoshihiro; Yamaguchi, Masaaki; Niizato, Tadafumi; Kitamura, Akihiro
no journal, ,
no abstracts in English
Niizato, Tadafumi; Abe, Hironobu; Ishii, Yasuo; Watanabe, Takayoshi; Mitachi, Katsuaki
no journal, ,
Environmental dynamics of radiocaesium and its outflow flux are crusial issues for the remediation of the Fukushima environment affected by contamination of the fall out of Fukushima Daiichi Nuclear Power Plant Accident. This paper presents the current status of field investigation and monitoring related to the dynamics and outflow flux of radiocaesium in the mountation forest, Abukuma Mountains, Fukushima, Japan.
Cs in sewage sludge ash and radioactivity concentration reduction methodKozai, Naofumi; Suzuki, Shinichi; Aoyagi, Noboru; Sakamoto, Fuminori; Onuki, Toshihiko
no journal, ,
Huge quantities of radionuclides were emitted by the accident at the Fukushima Daiichi Nuclear Power Plant and descended in wide areas of east Japan. A great amount of sewage sludge ashes (SSAs) containing fallout radionuclides (mainly Cs) at high concentration was generated and has been stored in sewage treatment plants until being disposed of. To contribute for the safety landfill disposal, we investigated the chemical states of Cs in SSAs by dissolution and static leach experiments. A fraction of Cs was contained in alkali metal salts, the major fraction of Cs was in iron oxides, and the rest was in silicates (quartz and feldspar). About 80-90% of Cs was contained in alkali metal salts and iron oxides and most of these solid phases were dissolved by heating in HCl aqueous solutions. These HCl-dissolvable phases were completely dissolved by pre-pulverizing SSAs and the subsequent heating in HCl aqueous solution at 95
C. The residues were mostly silicates and contained about 10-20% of Cs in the original SSAs. Several percent of Cs in the original SSA was leachable to synthetic seawater, while the Cs in the residue was non-leachable.
Onuki, Toshihiko; Sakamoto, Fuminori; Kozai, Naofumi; Shiina, Kazuhiro; Tanaka, Kenji; Namekawa, Jun
no journal, ,
Effect of the presence of minerals on the accumulation of radioactive Cs by hyphae of fungi has been studied. In the presence of mineral, radioactivity in the hyphae was less than that without mineral. This result indicates that presence of minerals inhibits the transportation of radioactive Cs from medium to the hyphae.
by microorganismsKato, Tomoaki*; Onuki, Toshihiko; Saito, Takumi; Kozai, Naofumi; Yu, Q.
no journal, ,
Reduction of MnO ions by the cells of microorganism has been studied. Mn(VII) was reduced by the cells to Mn(IV). In high cell density, Mn(VII) was reduced to Mn(III, II).
Malins, A.; Okumura, Masahiko; Machida, Masahiko; Saito, Kimiaki
no journal, ,
no abstracts in English
Okumura, Masahiko; Nakamura, Hiroki; Machida, Masahiko
no journal, ,
no abstracts in English
Yu, Q.; Onuki, Toshihiko; Tanaka, Kazuya*; Kozai, Naofumi; Yamasaki, Shinya*; Sakamoto, Fuminori; Tani, Yukinori*
no journal, ,
REEs were accumulated by MnO during oxidation of Mn(II) to MnO by manganese oxidizing fungus. In the presence of citate-Na, adsorption of REE was lowered than that without citrate. REE pattern in the solution showed positive anomaly in Ce, indicating that Ce(IV) was associated with organic materials excreted from the cells.