Authors:Y. Saito, Y. Miyamoto, M. Magara, S. Sakurai, and S. Usuda
In order to examine the feasibility of the adsorbed compounds on the pine needles for environmental monitoring of uranium, the adsorbed compounds were recovered by solvent washing, and the elemental concentrations in the compounds were compared with those of air particles and pine needles. It was found, that the concentration patterns of elements in the compounds corresponded to those of air particles, which meant that the air particles were the main components of the compounds. The analysis by ICP-MS suggested that the uranium in the compounds has a natural composition. Therefore, the adsorbed compounds to the pine needles can be considered as potential indicators for the environmental monitoring of uranium.
Authors:Y. Miyamoto, Y. Saito, M. Magara, S. Sakurai, and S. Usuda
In order to assess the extent of the elimination of humidity and the presence of pine trees on the elemental composition of
airborne dust, the concentration of 21 elements were measured in airborne dust collected with a high-volume sampler at JAERI
by instrumental neutron activation analysis (INAA). It was found that the concentration of soil-origin elements, such as Al,
Sc and Th, decreased as the humidity increased, and the Cl/Na ratio of sea salt constituent in the dust samples increased
with the decrease of humidity after the felling of the trees.
Authors:R. Doi, P. Sahunalu, C. Wachrinrat, S. Teejuntuk, and K. Sakurai
This study profiled soils over a land degradation gradient to obtain formulae as integrative measures for describing the gradient as a result of deforestation in Thailand. We applied antibiotic resistance most-probable-number profiling to the soil bacterial communities, and then described the gradient. Soil samples were collected on the gradient represented by dry evergreen forest (the original vegetation), dry deciduous forest (moderately disturbed) and bare ground (the most degraded) in February (dry season), March (shortly after temporal precipitation) and June (rainy season) 2001. In the period of this study, the degradation was consistently shown as soil conditions like sandy texture, high bulk density, lower pH, high exchangeable acidity, poor mineral and organic nutrients and dryness. Soil fertility index and soil evaluation factor, as the integrative measures of the intensity of land degradation, were described by scores on the first or the second principal component derived from the soil bacterial community profiles for each sampling time (R>0.457, p<0.043) and by scores on the third and fourth principal components for the overall data set (R>0.501, p<0.001), suggesting great dry to moist seasonal effects. Further, the changes had significant relationships with gradients of soil moisture content, acidity and/or soil nitrogen content. The data sets on the soil bacterial community profiles had more complicated data structures than the physicochemical data sets, suggesting effects of the physicochemical changes on the soil bacterial community. The differences between the bacterial and the physicochemical aspects suggest that it is advantageous to observe multiple aspects of soil quality when describing a soil-related gradient of interest.
Authors:J. Chai, Y. Miyamoto, Y. Kokubu, M. Magara, S. Sakurai, S. Usuda, Y. Oura, and M. Ebihara
In order to search for isotopic anomalies of U caused by the disintegration of 247Cm in meteorite samples, an analytical scheme for determining 235U/238U ratio for a small amount of uranium (less than 1 ng U) was established. The isotopic ratio of U was determined by double-focusing
inductively coupled plasma mass spectrometry (DF-ICP-MS). With a great improvement of chemical procedure for purifying the
uranium fraction separated from meteorite samples, a variation in 235U/238U ratios was resolved at an order of ±4‰ for 100 ppt or 200 pg U in solution. For applying the procedure in searching an evidence
of 247Cm as an extinct radionuclide in the early solar system, a selective chemical dissolution of constituent minerals of meteorites
using EDTA and HCl was introduced and a chemical purification scheme of uranium for ICP-MS was established.
Authors:M. Terai, A. Akabane, K. Ohno, S. Sakurai, F. Tsunoda, K. Hashimoto, and G. Nishida
Contents of 13 trace elements in human hair were determined by neutron activation analysis. The distribution patterns of mean
values of elements were extremely similar in all groups, though the contents of elements were individually different in each
group. Numerous elements in new-born infants of both sexes correlated with each other, especially with V at a 95% confidence
level. Special characteristics of diseased infants were the high contents of Cl and the low contents of Cr. It is presumed
that these facts are due to the imbalanced acid-base equilibrium and some abnormal metabolic systems in diseased bodies.
Authors:T. Mitsugashira, Y. Koma, S. Hirai, I. Okada, N. Kurashima, and H. Sakurai
Highly sensitive neutron activation analysis of uranium and thorium in high quality silica and aluminium has been investigated using the Japan Materials Testing Reactor (JMTR), having a thermal neutron flux higher than 1014 n/cm2/s. In order to determine ultra-low contents of uranium and thorium,239Np and233Pa as activation products were separated by using anion exchange and LaF3 coprecipitation methods. As a result, a number of interfering radioactive isotopes containing double neutron capture product such as183Ta were removed completely from the isolated239Np and233Pa fraction and the detection limits for uranium and thorium were found to be 2·10–12 g and 4·10–13 g, respectively.
Authors:Y. Saito-Kokubu, K. Yasuda, M. Magara, Y. Miyamoto, S. Sakurai, S. Usuda, H. Yamazaki, and S. Yoshikawa
In order to know the distribution of plutonium derived from the Nagasaki atomic bomb, soil samples were measured to determine
the 240Pu/239Pu isotope ratio of and concentrations of 239+240Pu and 137Cs. The 239+240Pu concentrations in soils, except for Nishiyama area, were close to the average concentration of soil collected in Japan.
In soils collected at the Nishiyama area and at the eastern area of Nagasaki Prefecture and at part of northern area in Kumamoto
Prefecture, the 240Pu/239Pu ratios were lower than the global fallout values. This suggests that plutonium from the atomic bomb was deposited in the
eastern area from the hypocenter reaching up to 100 km eastwards.
Authors:M. Takagaki, K. Ono, S-I. Masunaga, Y. Kinashi, Y. Sakurai, T. Kobayashi, S-I. Miyatake, and N. Hashimoto
Quantitative determination of ppb-order 10B was carried out in a small number of cultured tumor cells by particle tracks by the 10B(n,)7Li reactions using solid state nuclear track detector (SSNTD) for boron neutron capture therapy research. The detection limit of 10B concentration in tumor cells is less than 1·10-3 ppm under our experimental conditions which permits the quantitative determination of 10B in a small number of boronated tumor cells (105/ml = ca. 0.1 mg). Boron quantities in tumor cells determined were well compatible with the tumor cell killing effects of boron neutron capture therapy.
Authors:C. Lee, K. Iguchi, J. Inagawa, D. Suzuki, F. Esaka, M. Magara, S. Sakurai, K. Watanabe, and S. Usuda
An improved method of fission track (FT) sample preparation was developed, in which the detector of fission track and the
layer containing particles are separated, in order to apply the FT-thermal ionization mass spectrometry (TIMS) for particle
analysis of safeguards environmental samples. The developed FT sample enabled us to detect the particle of interest simply
by observing the fission tracks. The process of particle identification was difficult due to the discrepancy between the position
of the particles and fission tracks, which were observed in the conventional FT sample. The proposed method has significantly
resolved this problem.