@article{oai:nipr.repo.nii.ac.jp:00003716,
 author = {ナカザワ, タカキヨ and マチダ, トシノブ and エスミ, ケンジ and タナカ, マサユキ and フジイ, ヨシユキ and アオキ, シュンジ and ワタナベ, オキツグ and NAKAZAWA, Takakiyo and MACHIDA, Toshinobu and ESUMI, Kenji and TANAKA, Masayuki and FUJII, Yoshiyuki and AOKI, Shuhji and WATANABE, Okitsugu},
 journal = {Proceedings of the NIPR Symposium on Polar Meteorology and Glaciology},
 month = {Feb},
 note = {P(論文), Dry and melt extraction systems have been developed to determine respectively the CO_2 and CH_4 concentrations of ancient air trapped in the polar ice core. The day extraction system was confirmed to be capable of crushing a core sample of 1kg to fine powder within 2 min, and its air extraction efficiency was estimated to be 98%. The air for the CH_4 measurements was extracted by melting core samples in an evacuated chamber. The CO_2 and CH_4 concentrations were determined using gas chromatography. The overall precision of our analyses is better than ±1 ppmv for CO_2 and ±10 ppbv for CH_4. Two Antarctic ice cores were used in this study. The ice core drilled at Mizuho Station (70°42'S, 44°20'E) showed that pre-industrial levels of the CO_2 and CH_4 concentrations (3300-200 yrs BP) were 279-287 ppmv and 690-750 ppbv, respectively and both concentrations increased rapidly for the last 200 years. It was also found that the CO_2 concentrations between 800 and 200 yrs BP were higher by almost 7 ppmv than those in remaining pre-industrial time, due probably to CO_2 release from the oceans and/or the biosphere. The Yamato core drilled near the end of ice flow (near the Yamato Mountains) showed concentrations of 230-240 ppmv and 530-580 ppbv for CO_2 and CH_4,respectively, which are apparently lower than post-glacial background levels, implying that the core was formed in the glacial period.},
 title = {AIR EXTRACTION SYSTEMS FOR ICE CORE AND CO_2 AND CH_4 CONCENTRATIONS IN THE PAST ATMOSPHERE},
 volume = {5},
 year = {1992}
}