| Budget Amount *help |
¥3,300,000 (Direct Cost: ¥3,300,000)
Fiscal Year 2005: ¥700,000 (Direct Cost: ¥700,000)
Fiscal Year 2004: ¥600,000 (Direct Cost: ¥600,000)
Fiscal Year 2003: ¥2,000,000 (Direct Cost: ¥2,000,000)
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| Research Abstract |
In this study, major/trace elements and radionuclides in various atmospheric samples, i.e. particulate matter (PM) samples collected weekly at Kawasaki from October 2002 to January 2005 and the bulk deposition samples collected monthly at Fukuoka, Nagasaki, Tsukuba and Kawasaki in 1964 and 2000 to 2004, were determined by using ICP-AES, neutron activation analysis and γ-ray spectrometry. Consequently, we obtained some valuable information in this study as follows ;
1.From the correlation coefficient between the concentrations of determined elements, Br-Sb and Sc-Fe-La showed a good correlation, respectively. Considering the size distributions in PM10, it was seen that the contribution of PM10 was higher than that of larger one in Br-Sb and Se-Fe-La, respectively.
2.In the average concentrations of radioactivities of ^<210>Pb and ^7Be each direction of the wind, those when the south wind blew were higher than those when the north wind did. It could be seen that ^<222>Rn, the ancestor of ^
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<210>Pb, was diffusing 1000 times much or more as in the continent compared with in the ocean and ^7Be was influenced by the latitude effect of cosmic rays. Furthermore, it was found that the concentrations of both nuclides in those samples would be dominated by the rainfall.
3.It can be seen that the lanthanoid abundance patterns in the Nagasaki depositions from March to May are very similar to that of the yellow soil dust (Kosa) in Nagasaki. This fact shows that the Nagasaki depositions during those months would be strongly influenced by Kosa. In addition, it became clear from the Th/Sc ratios in those samples that the contribution of Kosa was higher in the depositions in recent years (2000 to 2004) than in those in 1964.
4.The temporal variation of the elements (Si,Al, lanthanides, Th etc) originated in soil was almost coincided with total amounts of the samples excluding those collected at Fukuoka in summer in 2000. It was suggested that the soil dusts dominated the total amounts of the depositions.
5.The concentrations of uranium, radioactivities of ^<137>Cs and the U/Th ratios in the deposition samples in 1964 were apparently higher between March and May than those in other months. It seems that the deposition samples in 1964 reflected the active stratosphere-troposphere air exchange in the springtime and were affected by the nuclear test during 1962-1963. Less
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