| Budget Amount *help |
¥42,770,000 (Direct Cost: ¥32,900,000、Indirect Cost: ¥9,870,000)
Fiscal Year 2003: ¥4,550,000 (Direct Cost: ¥3,500,000、Indirect Cost: ¥1,050,000)
Fiscal Year 2002: ¥5,590,000 (Direct Cost: ¥4,300,000、Indirect Cost: ¥1,290,000)
Fiscal Year 2001: ¥32,630,000 (Direct Cost: ¥25,100,000、Indirect Cost: ¥7,530,000)
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| Research Abstract |
Distribution and trend of atmospheric carbon tetrafluoride (CF4) concentration by its precise and accurate measurement adopting atmospheric stable Krypton(Kr) as an internal standard was mainly developed. While CF4 is the strongest global warming gas, the measurement of its atmospheric concentration reported so far contains much larger uncertainties than the annual increment or the distribution gradient due to the worse trapping efficiency or unstable collection factor during the preconcentration process prior to GC/MS analysis because of its close properties to the major components of the air. An efficient and reproducible preconcentration method was developed and combined with the newly adopted atmospheric Kr as an internal standard because of their close physical properties and similar behaviors during the preconcentration and the GC/MS measurement. Since Kr exists uniformly and constantly in the global atmosphere with no variation or trend, extraordinarily improvement of the precision of CF4 determination (from several per cents to less than one per cent) was attained by normalizing the CF4 peak with a Kr isotope peak in the GC/MS measurement. The sample volume necessary was also extremely reduced. The precise and accurate distributions and trends of CF4 in the troposphere and stratosphere were obtained from the samples newly collected and those stored in our laboratory for more than 20 years. During our attempt of the precise determination of trace gases in the atmosphere by using atmospheric Kr as the internal standard, we noticed that the atmospheric Kr concentration of 1.14±0.01 ppmv which had been quoted through half a century was different from the observation. The Kr concentration we obtained with three step concentration followed by precise GC/MS measurement was 1.099±0.004 ppmv, about 4% lower than the currently accepted value.
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