A radiological survey and whole body counting of 137Cs were carried out in Rongelap Island (main island) of Rongelap Atoll in July 1999. The maximum values of 137Cs contamination and of g-ray dose rate were 39 kBq/m2 and 0.033 mSv/h, respectively. The maximum a and b gross counting rates on the surface of ground were 1 cpm and 182 cpm in active area of 72 cm2, respectively. Activity of 239,240Pu for soil was 80 Bq/kg in the top 5 cm and aerial deposition was 3.4 kBq/m2 in Rongelap Island in 1999. The body burden of 137Cs was observed to be 27±11 Bq/kg for 6 workers. Assessment of external and internal annual doses (0.1 and 0.07 mSv/y) indicates that as of 1999 there is no large risk to the inhabitants of Rongelap Island from a radiological point of view. The radiological status of Rongelap Island, which was severely contaminated by the radiological fallouts of nuclear testings carried out in 1954, has improved year by year as shown by the decrease of 137Cs. The effective halftime of 137Cs, which is estimated to be 6.6 y is much shorter than the physical half-life of 137Cs. Radioactive contamination in Kaballe Island, (a part of the northern islands used for farming) which is located 25 km northeast of Rongelap Island, was still high in 1999. One site nearby a beach was highly contaminated with 137Cs, where the maximum activity of 137Cs was 3.4 MBq/m2, a-ray of 2 cpm, b-ray of 1205 cpm and g-ray of 0.73 mSv/h. Activity of 239,240Pu in soil (n = 1) was 294 Bq/kg (top 5 cm) and 16 kBq/m2.
A simple method has been developed for evaluating the neutron spectrum and the temperature by using U, Sb, Cr, Co and Lu as monitors and successfully applied to the routine analysis. For most of nuclides, amounts determined by the method showed reasonable agreements with those added. However, there have been found several nuclides which gave erroneous results beyond the permissible limits. In the case of128I, the reason for the deviation was found to lie on the normalization factor of -ray abundances that are in common use. This was confirmed by using I2 doped polyacethylene which is a material highly resistant to ionizing radiations.46Sc,175Yb and several other rare earth nuclides are discussed as well.
A pre-irradiation group separation method has been developed for the neutron activation analysis of rare earth elements (REE) and Ba in silicate rocks. REE and Ba were quantitatively separated from other elements by cation exchange column method. The chemical yield of each separation was monitored with Pr added to the sample powder before decomposition. The accuracy and precision were tested by repeated analyses of JB-1 and one analysis of BCR-1. In addition, it was found that REE distribution in a granitic rock powder was inhomogeneous and therefore special care must be taken for the sampling of granitic rock powders.
Authors:M. Koyama, M. Shirakawa, J. Takada, Y. Katayama, and T. Matsubara
More than 2000 samales of land plant leaves, mostly of tree, have been analyzed by neutron activation analysis in order to find out macroscopic relations between distributions of chemical elements in plants and soil characteristics. The distributions of the elements in plants were also examined from the view point of botanical taxonomy or phylogeny. New species which accumulate Co, rare earths, Ba, Ra, heavy halogens and some other elements have been found. Capability or potentiality for accumulating elements could be related to higher ranks of taxonomy, that is, genus or family. The nature of soil is also found to have profound effects on the extent of accumulation of elements in plants.
Authors:K. Kawamoto, T. Sumino, J. Takada, Y. Tanaka, and M. Akaboshi
Several rare earth elements (REEs) and other elements in algae were investigated by ICP-MS and INAA. Algae materials were
supplied from an IAEA Intercomparison Study:Chlorella vulg. grown under reduced levels of toxic elements (IAEA-391) and IAEA-393 algae was grown in a medium to which certain toxic elements
were added. 34–691 mg of algae samples were dissolved in conc, nitric acid using a microwave sampleppreparation system. REEs
could be detected in the order of magnitude of 10−3 ng/g by ICP-MS. Activation analysis failed to detect any REEs because of a strong interference due mainly to24Na and32P. The distriubtion patterns of these REEs in algae slightly differed from those ofCarya sp. and tobacco leaves, and differed significantly from that of fern leaves. The distribution pattern was rather similar to that
found in the North American shale composite (NASC).
Authors:M. Akaboshi, Y. Tanaka, T. Sumino, J. Takada, and K. Kawai
The literature indicates that the interaction of Tb3+ with DNA modified by the antitumour drug cis-diaminedichloroplatinum(II) (CDDP) results in substantial enhancement of the
fluorescence of this cation, while no enhancement is observed in the case of DNA modified by irradiation with ionizing radiation.
This study investigates the effect of Tb3+ on the survival of cultured mammalian cells treated with CDDP. HeLa cells were treated with a combination of195mPt-CDDP and TbCl3, and the relationship between lethal effect and the numbers of Tb and/or Pt atoms binding to DNA, RNA and proteins was examined.
The Tb content in each fraction was determined using instrumental neutron activation analysis. It was found that the cytotoxic
effect of CDDP was greatly enhanced by the presence of Tb ions (D0 of CDDP fell from 8.3 μM without Tb to 3.2 μM with 0.75 mM Tb), while no such effect was found in radiation-induced cell-killing.
The number of Tb atoms bound to DNA molecules in a cell was calculated to be about 4.5·107, namely 1 per 1.400 nucleotides, under that situation.
Authors:J. Takada, T. Sumino, Y. Tanaka, K. Nishimura, and M. Akaboshi
The lanthanides (REEs) in 142 fern leaves collected from 9 sampling sites in Japan were analyzed by instrumental neutron activation
analysis. Between two REEs a strong positive correlation was found in the logarithmic scattering diagram with correlation
and regression coefficients close to unity, suggesting neither selective accumulation by plants nor different availability
from soil between the two elements. However, between Tb and the other REEs the relationship showed two lines with the same
correlation coefficient. This suggested that there must be a difference in the availability of REEs or in their absorption
characteristics by plants. Further analysis revealed that the splitting was due to some difference in the environmental factors
where the fern grew. However, the amount of REE in the soil collected together with the corresponding fern did not reflect
the REE concentration in the fern leaves.
Authors:M. Akaboshi, K. Kawai, Y. Tanaka, J. Takada, and T. Sumino
The effect of hyperthermia on the cell killing efficiency of Pt atoms binding to DNA, RNA and protein molecules of HeLa cells
treated withcis-diamine(1,1-cyclobutanedicarboxylato)platinum(II) (CBDCA) was examined. HeLa S-3 cells were treated with195mPt-radiolabeled CBDCA for 60 minutes at various temperatures, and the relationship between the lethal effect and the number
of Pt atoms binding to DNA, RNA and proteins was examined. The mean lethal concentration (D0) of carboplatin for a 60 min-treatment at 0, 25, 37, 40, 42 and 44°C was 671.2, 201.5, 67.3, 33.4, 20.2 and 15.6 μM, respectively.
By using identically treated cells, the number of Pt-atoms combined with DNA, RNA and protein molecules were determined in
the subcellular fractions. Thus, the D0's given as the drug concentrations were replaced with the number of Pt-atoms combined in each fraction. Then, the cell-killing
efficiency of the Pt atom was expressed as the reciprocal of the number of Pt-atoms combined and was calculated for each molecule.
The efficiency for DNA molecules was 0.699, 1.42, 2.65, 4.84, 7.74 and 8.28·104 nucleotides, respectively, for the conditions described above. From 0 to 44°C, the cell-killing efficiency of Pt atoms increased
by a factor of 11.9.
Authors:S. Koh, T. Aoki, Y. Katayama, and J. Takada
Losses of trace elements in plant samples after dry ashing were investigated. Plant samples were heated in crucibles at 105–600°C
for 0.5–24 hours in a muffle furnace. The amounts of elements remaining after heating were determined by INAA. The amounts
of Cl and Br decreased over the range 200–400°C in all samples, especially in stem samples. The amount of Na increased over
the range 450–600°C, possibly because of contamination from the crucibles. Dry ashing is suitable for analyzing most elements
in plant samples.
Authors:M. Yamamoto, M. Hoshi, J. Takada, A. Sekerbaev, and B. Gusev
Field missions were sent to Semipalatinsk City and several settlements near the former Semipalatinsk nuclear test site to
investigate the current radioactive contamination levels of the land coming from long-lived radionuclides. The soil was sampled
at about 20 sites, including some settlements such as Mostik, Dolon and Chagan, forest and pasture areas, along the roads
from Semipalatinsk City to Kurchatov City and to Korosteli settlement in the direction of the Altai District. The radioactivities
of137Cs,238Pu and239,240Pu as well as240Pu/239Pu atomic ratios in the soil were determined by non-destructive γ-ray spectrometry and radiochemical separation followed by
α-ray spectrometry and/or ICP-MS, respectively. The results showed a distinction of137Cs and239,240Pu inventories in soil depending on the site where we visited. While the overall137Cs levels were as same as or slightly lower than the domestic global fallout level (3·103–7·103 Bq/m2),239,240Pu levels at some sites were several to a few ten times higher than the domestic level (40–120 Bq/m2). The atomic ratios of240Pu/239Pu in the soil were in the range of 0.024–0.125, which were significantly lower than the value of 0.18 commonly accepted for
global fallout Pu.