Time filter

Source Type

Kashiwa, Japan

Shimamura T.,Kitasato University | Iijima S.,JASCO Corporation | Hirayama M.,Entex Inc. | Iwashita M.,Kitasato University | And 3 more authors.
Journal of Trace Elements in Medicine and Biology | Year: 2013

The concentrations of 26 major to trace elements in rat kidneys aging from 5 to 113 weeks old were determined. The rats investigated were the same rats used previously reported to have 29 elements in bones (femurs). The samples were decomposed by high purity nitric acid and hydrogen peroxide. Eight elements (Na, Mg, Si, P, K, Ca, Fe and Zn) were determined using inductively coupled plasma atomic emission spectrometry (ICP-AES) and 18 elements (Mn, Co, Ni, Cu, As, Se, Rb, Sr, Mo, Cd, Sn, Sb, Cs, Ba, Tl, Pb, Bi and U) were determined using inductively coupled plasma mass spectrometry (ICP-MS). The aging effects on the concentrations of these elements and mutual elemental relationships were investigated. Analysis of variance (ANOVA) for age variations indicated that the concentrations of P, K, Mn and Mo were almost constant across the age of rats (p>0.3). The concentration of many elements such as Na, Mg, Ca, Fe, Co, Cu, Zn, As, Se, Cd, Sn, Sb, Tl, Pb and Bi, showed significant increasing trends (p<0.01) with different patterns. Rubidium, Cs, Pb and Bi showed significant age variations but not monotonic trends. Silicon, Ni, Sr, Ba and U showed large concentration scatterings without any significant trends (p>0.01). The metabolism of these elements may not be well established in the kidney. Many toxic elements such as As, Cd, Sn, Pb and Bi showed a narrow concentration range among age-matched rats. The kidney may have established metabolic mechanisms to confine or accumulate these toxic elements even though their concentrations are very low (e.g., 10ngg-1 of Cd). These elements also closely coupled with Fe. A cluster analysis was performed using an elemental correlation matrix and indicated that these elements, including Fe, formed a cluster. However, another cluster analysis using " an aging effect eliminated" elemental correlation showed different clustering in which the Fe, Cd cluster disappeared. © 2012 Elsevier GmbH.

Akata N.,Japan Institute for Environmental Sciences | Kakiuchi H.,Japan Institute for Environmental Sciences | Shima N.,Entex Inc. | Iyogi T.,Japan Institute for Environmental Sciences | And 2 more authors.
Journal of Environmental Radioactivity | Year: 2011

This study aimed at obtaining background tritium concentrations in precipitation and air at Rokkasho where the first commercial spent nuclear fuel reprocessing plant in Japan has been under construction. Tritium concentration in monthly precipitation during fiscal years 2001-2005 had a seasonal variation pattern which was high in spring and low in summer. The tritium concentration was higher than that observed at Chiba City as a whole. The seasonal peak concentration at Rokkasho was generally higher than that at Chiba City, while the baseline concentrations of both were similar. The reason for the difference may be the effect of air mass from the Asian continent which is considered to have high tritium concentration. Atmospheric tritium was operationally separated into HTO, HT and hydrocarbon (CH3T) fractions, and the samples collected every 3 d-14 d during fiscal year 2005 were analyzed for these fractions. The HTO concentration as radioactivity in water correlated well with that in the precipitation samples. The HT concentration was the highest among the chemical forms analyzed, followed by the HTO and CH3T concentrations. The HT and CH3T concentrations did not have clear seasonal variation patterns. The HT concentration followed the decline previously reported by Mason and Östlund with an apparent half-life of 4.8 y. The apparent and environmental half-lives of CH3T were estimated as 9.2 y and 36.5 y, respectively, by combining the present data with literature data. The Intergovernmental Panel on Climate Change used the atmospheric lifetime of 12 y for CH4 to estimate global warming in its 2007 report. The longer environmental half-life of CH3T suggested its supply from other sources than past nuclear weapon testing in the atmosphere. © 2011 Elsevier Ltd.

Akata N.,Japan Institute for Environmental Sciences | Abe K.,Japan Institute for Environmental Sciences | Kakiuchi H.,Japan Institute for Environmental Sciences | Iyogi T.,Japan Institute for Environmental Sciences | And 3 more authors.
Health Physics | Year: 2013

The contribution of atmospheric discharged 14C to local 14C concentrations was investigated by analysis of 14C in environmental samples collected around the spent nuclear fuel reprocessing plant in Rokkasho, Aomori, Japan. From June 2006 to October 2011, the range of monthly averaged specific activities in atmospheric CO2 collected 2.6 km from the plant was 0.226Y0.279 Bq g C-1; at several sampling times, the observed concentrations were higher than the background value. Specific activities of atmospheric 14C simulated with an atmospheric dispersion model coupled with a mesoscale weather model reproduced the measured values fairly well, supporting the idea that the higher measured specific activities were due to 14C discharged from the reprocessing plant. For investigation of the 14C distribution around the facility, samples of Cyperus microiria,wild annual sedge, were collected from nine locations. Plant samples collected east and west of the facility in 2008 showed slightly higher specific activities than samples collected at the other locations, reflecting the prevailing wind direction. The measured 14C specific activities in vegetable, polished rice, pasture, and milk samples collected around the facility did not differ significantly from the background value (except for one polished rice sample, which had a value slightly higher than background). The annual committed effective radiation dose to humans resulting from consumption of the polished rice was estimated as 3.6 × 10-4mSv, which is negligibly small compared with 1 mSv, an index of the dose limit for the general public. Copyright © 2013 Health Physics Society.

CenterPoint Energy and Entex Inc. | Date: 1975-12-23


Akata N.,Japan Institute for Environmental Sciences | Kakiuchi H.,Japan Institute for Environmental Sciences | Kanno K.,Entex Inc. | Shima N.,Entex Inc. | Hisamatsu S.,Japan Institute for Environmental Sciences
Fusion Science and Technology | Year: 2011

In order to study the areal distribution of 3H in the atmosphere around the spent nuclear fuel reprocessing plant in Rokkasho, Japan, we developed a passive type sampler of atmospheric water vapor and tested its usability in the field. A polyethylene bottle with a porous polyethylene membrane at the opening was used as the sampler. The bottle contained 30Og of molecular sieve 3A (MS-3A) for adsorbing water vapor passing through the membrane. The concentration of 3H in water recovered from the MS-3A in the bottle was compared with that obtained by an active type sampler. Both 3H concentrations agreed well with each other, which showed that the method developed was practical and effective. Using the passive type samplers at nine sampling points around the nuclear fuel reprocessing plant in November and December 2007, we successfully obtained the monthly area distributions of 3H concentrations in the atmospheric water vapor.

Discover hidden collaborations