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Abstract  

Tritium concentrations were analyzed for coastal seawater and lake water collected from various places in Japan. Low tritium concentrations were observed for coastal seawater of small islands and it was attributed to a short residence time of the ground-water in such a small island. Tritium concentrations in lake water showed a significant variation. And it was revealed that the size of the lake and its drainage area were the dominant factors controlling the tritium concentrations in lakes.

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Abstract  

Tritium concentrations were measured for river waters on two islands in Japan. Significant difference was observed on the distribution of tritium concentrations on both islands, the river water samples from the northern island had higher concentrations and the average was about twice compared to that from the southern island. Higher tritium concentration in precipitation and the larger area of the northern island would be responsible for higher tritium concentrations in river waters.

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Abstract  

We have observed an anomalous90Sr deposition at the Meteorological Research Institute (MRI), Tsukuba, Japan during the fall of 1995. This anomalous90Sr deposition was confirmed by the re-analysis of the sample, the associated lowest137Cs/90Sr activity ratio and high r/s ratio, etc. We discuss the cause of this anomalous90Sr deposition and conclude that the anomalous90Sr may come from an accidental release of nuclear battery, etc.

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Abstract  

A nondestructive photon activation analysis with 30 MeV bremsstrahlung has been applied to the multielement determination in the floor sediments in a region of the Japan Sea. The abundances for 5 major and 11 trace elements were measured in several terrigeous and pelagic deposits, discussion being given on the results. Enrichments in certain trace elements, such as Mn, Ni and Co, were observed in the samples of pelagic areas, but to less extent relative to those of the mid-Pacific areas.

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The daily variation of14C concentrations of liberated CO2 in the free fermentation process of Japanese SAKE brewing was studied. Each of the concentrations measured in the initial and final stages of the fermentation process correlated with levels of koji rice and steamed rice used for SAKE production, which had been obtained from different areas. This shows that analysis of fermenting CO2 of SAKE could be used to estimate the14C level in a local environment.

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Chemical compositions of suspended particulate matter (SPM) in atmosphere collected at Hachioji and Sakata in Japan from 2002 to 2004 were determined by prompt gamma-ray analysis and instrumental neutron activation analysis. About 40 elemental concentrations in SPM could be determined, and enrichment factors and elemental correlations were examined. Several elements such as Cl, Cr, Ag, Sb, and W were largely different between Hachioji and Sakata, although their sources are not clear at present.

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Abstract  

We measured radiocarbon age of an ancient document “Minamoto no Yoritomo Sodehan Migyosho”. The content tells that it was issued in 1189 by “Minamoto no Yoritomo” known as the virtually first shogun in Japan to grant “Matsugi” family the privilege of controlling craftsmen of foundry industry. Paleographical views, however, suggested that it can be a counterfeit. The radiocarbon dating clarified that the document was written not in the 12th but after the 16th century.

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Abstract  

The distribution of minor and trace elements in biological samples is very informative for bio-medical and environmental research. Particle induced X-ray emission (PIXE) analysis is a powerful tool for this subject since it can analyze many elements in samples non-destructively at high sensitivity and, with an advantage of micro-beam scanning capability. Recent studies in Japan on the application of PIXE analysis to these fields are introduced in this paper.

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Abstract  

In order to obtain the information about plutonium contamination in ocean environment, plutonium in the internal organs of squid collected from Japanese inshore were determined by HR-ICP-MS. Although the plutonium was detected in all samples collected in 1980"""s, the concentration is almost the same level as the detection limit (1 to 3 mBq/kg wet) in recent years. The atomic ratio of 240Pu/239Pu in all samples was slightly higher than the value of global fallout.

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Abstract  

To clarify environmental effects of the Chemobyl radionuclides, long-lived Chernobyl radioactivity (239,240Pu,238Pu,241Pu and90Sr) in deposition samples in May 1986 was measured at 11 stations in Japan. Temporal variation of weekly deposition of90Sr differed from that of volatile radionuclides such as131I and137Cs, which may reflect the released process at Chernobyl. On the other hand, the geographical distributions of the monthly deposition of long-lived radionuclides were similar to those of volatile radionuclides, in which maximum deposits of90Sr and plutonium were observed in Akita, a northwestern Japan Sea coast site of Honshu Island. Higher241Pu deposition in most of the stations, as well as high238Pu/239,240Pu activity ratios were observed. The241Pu/238Pu activity ratios in deposition samples were nearly equal to that in the total release, which is clear evidence that Chernobyl-derived plutonium was transported to Japan in May 1986 together with volatile radionuclides although the contribution of Chernobyl Pu was about three orders of magnitude lower than137Cs.

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