Environmental factors (nutrients and pH) influence the retention of Sr, Cs, and Ba as analogue of long-lived radionuclides by the microorganism. The effect of pH and concentration of organic nutrients are proved to be significant factors for retention of cations (Sr, Cs and Ba) by the microorganisms inoculated from surface soil. Microorganisms can affect the speciation of Sr, Cs, and Ba in the environment. Concentration of organic nutrients and pH are indicated to be the important environmental factors in the consideration of the migration of the radionuclides through microbial processes in the terrestrial environment.
Authors:N. Momoshima, H. Kakiuchi, Y. Maeda, E. Hirai, and T. Ono
Concentrations of239+249Pu in environmental samples were detemined by ICP-MS and spectrometry, showing consistent results, which suggests an applicability of ICP-MS to239Pu and240Pu measurement. The activity ratios of238Pu/239+240Pu and240Pu/239Pu were significantly different in samples from the general environment and near Sellafield reprocessing plants, indicating the usefulness of these ratios for identification of the Pu contamination source.
Authors:N. Momoshima, H. Kakiuchi, T. Okai, S. Hisamatsu, and Y. Maeda
Tritium concentrations were analyzed in organic and water fractions of fresh pine needles, dead and degraded pine needles accumulating on a pine forest floor to examine tritium cycle in a forest ecosystem. Tritium concentration was higher in the organic fraction of dead and degraded pine needles compared to others, suggesting two tritium sources. Rain is responsible for water fractions in the samples, while atmospheric hydrogen and methane are speculated to be responsible for high tritium level in the organic fraction of dead and degraded pine needles.
Authors:Y. Hayashi, N. Momoshima, Y. Maeda, and H. Kakiuchi
Tritium concentrations in rain collected at Fukuoka, Japan from 1982 have been measured. From May 1996 tritium concentrations
and chemical species have been analyzed for each rain to examine their relationship. Recent rain was concluded not to be affected
by tritium from atmospheric nuclear tests. Tritium concentrations showed a seasonal pattern, high during winter and spring
and low during summer and fall and had positive correlations with non-sea-salt SO4−2, indicating a long distance transport of acidic materials as tritium from continental China.
Authors:H. Kakiuchi, N. Momoshima, T. Okai, and Y. Maeda
Surface seawater and water vapor about 10 m above the sea level were collected in the Pacific and Indian Oceans during the
expedition of KH-96-5 to examine tritium concentrations in open sea. The tritium concentration in the water vapor was one
order of magnitude higher than that in the surface seawater, attributed to downward movement of naturally occurring tritium
from stratosphere to troposphere.
Authors:S. Ueda, H. Kakiuchi, K. Kondo, and J. Inaba
In order to identify the concentration of tritium (3H) in areas of fresh, brackish and sea water, bordered by nuclear fuel facilities at Rokkasho-Village, Aomori, Japan, water
samples were collected from 2001 to 2004 at six points in those areas. Concentration ranges of tritium in fresh river water,
brackish lake and seawater samples were 0.60 to 1.1 Bq. l-1(mean value 0.79 Bq. l-1), 0.20 to 0.87 Bq. l-1(mean value 0.41 Bq. l-1), and 0.08 to 0.25 Bq. l-1(mean value 0.15 Bq. l-1), respectively. Relationships between tritium concentrations and salinity in the samples showed a clear negative correlation.
Moreover, the seasonal variation of tritium in water from Rokkasho-Village was high in spring and low in fall.
Authors:N. Momoshima, H. Kakiuchi, T. Okai, and Y. Maeda
Variation of tritium concentration was examined for 100 days in the course of degradation of fresh pine needles, which were
left on a pine forest floor. No difference was observed on free water tritium (FWT) and organically bound tritium (OBT) concentrations
of sterilized samples by gamma-ray irradiation or fumigation and control samples, attributable to incomplete sterilization.
The OBT concentrations did not increase within the experimental period as the level of humus collected from the forest floor.
The results suggest that a longer degradation time, more than 100 days, is necessary to elevate OBT up to the level, which
is observed in the general environment.
Authors:G. Wakabayashi, H. Ohura, T. Okai, M. Matoba, A. Nohtomi, H. Kakiuchi, N. Momoshima, and H. Kawamura
A simple analytical method for environmental14C with a low background liquid scintillation counter was developed. We used a new gelling agent, N-lauroyl-L-glutamic-α,γ-dibutylamide,
for the liquid scintillation counting of14C as CaCO3 (gel suspension method). Our procedure for sample preparation was much simpler than that of conventional methods and required
no special equipment. The samples prepared with the standard sample of CaCO3 were measured to evaluate the self absorption of the sample, the optimum condition of counting and the detection limit. Our
results indicated that the newly developed technique could be efficiently applied for the monitoring of environmental14C.
Authors:G. Wakabayashi, H. Ohura, T. Okai, M. Matoba, H. Kakiuchi, N. Momoshima, and H. Kawamura
Stability and reproducibility of gel-suspension samples were investigated in order to evaluate the characteristic feature
of the gel-suspension method for14C activity measurement. Commercially available gelling agent, N-lauroyl-L-glutamic-α,γ-dibutylamide, was used for the gelformatio
of the samples. No change of the counting rate for the gel-suspension sample was observed for more than 2 years after the
sample preparation. Four samples used for checking the reproducibility of the sample preparation method. The same values were
obtained for the counting rate of14C activity within the counting error. No change of the counting rate was observed for the “re-gelated” sample. These results
show that the gel-suspension method is appropriate for the14C activity measurement by the liquid scintillation method and is useful for a long-term preservation of the sample for repeated