著者

鳥居 鉄也 Tetsuya TORII

雑誌

南極資料 (ISSN:00857289)

巻号頁・発行日

vol.33, pp.1-26, 1968-12

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The 8 th Japanese Antarctic wintering party led by Dr. T. TORII consists of 24 members, of which 14 are scientists and the rest logistics supporters. The party was organized succeeding the 7th wintering party, with its project centered on aeronomy andbiology. Items of obseivation are as follows cosmic rays, aurora and aiiglow, lonospheie, atmospheric emissions over a wide range of radio frequencies (ELF, VLF, LF, RF), geomagnetism, meteorology, natural earthquake, biology, glaciology, geomorphology, geochemistry, etc. Construction for the second year after the renovation of Syowa Station included 5 buildings aeronomy laboratory, mess hall, balloon inflation shed, garage and air traffic control building. Keeping pace with the improvement of facilities at the base, consumption of water has increased. Unfortunately, a break developed in a small reservoir, so that the water supply for the summer season was dependent on puddles on sea ice around the base. Electric power was supplied by a separate 20KVA generator for scientific instruments in order to prevent electric noise, and the 45KVA generator was used for general purposes. Shortage in power supply suggested the need for installation of another generator. Two field trips were made to the foreign stations. One trip was to Molodezhnaya Station from August 17 through September 2, 1967. The trip, which covered the course along the east Prince Olav Coast, was designed for observation of gravity, geomorphology, glaciology, biology and geochemistry. The other inland traverse was undertaken from November 5, 1967 through January 15, 1968. The course ran along the longitude 43°E to latitude 75°S and then direct to Plateau Station, having carried out the observation of meteorology, glaciology, geomorphology, geomagnetism and geochemistry. VLF observation was not performed because of a trouble in machinery. The party returned to the base by the same route. Cooperation and help extended by the U. S. A. and USSR parties during the field trips are gratefully acknowledged by the Japanese wintering party. Regular communications with Mawson Station on meteorological data were made five times a day. Data on seismology, Kindices, cosmic rays, etc. were exchanged between the base and U. S A., New Zealand, Australian, French, and USSR stations. Information supplied from IUWDS through Mawson on geoalert and geocast was very useful for the aeronomy group at this base On February 9, 1968 the body of the late Dr. Shin FUKUSHIMA was discovered on the west Ongul Island, 4.2km from the base, 7 years and 4 months after he was reported missing He had gone out of a mess hall on October 10, 1960 and got lost in the blizzard on his way back. The ramams weie cremated on the spot with Buddhist rites

著者

堀内 公子 鳥居 鉄也 村上 悠紀雄 Kimiko HORIUCHI Tetsuya TORII Yukio MURAKAMI

雑誌

南極資料 (ISSN:00857289)

巻号頁・発行日

vol.58, pp.69-80, 1977-03

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ドライバレー地域の掘削で得られたDVDP 13コアー試料とベストフォールド・ヒルズの湖底堆積物について,過塩素酸可溶部と不溶部の炭酸ナトリウム融解抽出部のそれぞれの中のRa量を求めた.Raの定量は放射平衡に達したRnを液体シンチレーションカウンターで測定した.BGが45 cpmのとき,その1/8を測定下限とすると,2gの試料で0.25±0.04×10^<-12> Ci/g のRaの測定が可能である.UとThとの地球化学的な行動が異なることに基づいて考察すると,Uは海水で運ばれ,生成した^<230>Thが沈積しやすく,娘核種の^<226>Raとは一万年弱で放射平衡に達する.放射平衡に達するまで^<226>Raの量は次第にふえ,それから7.5×10^4年の半減期で減少していく.ゆえに過塩素酸可溶部と炭酸ナトリウム融解部のRaを定量することにより,堆積生成以来のおよその年代の古さを知り得る.ドライバレー地域では前者の値が後者より数倍も多く今回の試料中で最も古く,スチニア湖湖底堆積物は最も新しいと推定した.The ignition loss and the Ra content in the 10% HClO_4-soluble fraction and Na_2CO_3-fusion fraction were respectively determined for the 17 core samples (DVDP 13 core), down to the depth of 50 meters and for the four lake deposits in the Vestfold Hills. The determination of Ra was performed by measuring the activity of Ra in radioactive equilibrium state with a liquid scintillation counter. The detection limit of Ra with 2 grams of sample wag (0.25±0.04)×10^<-12> Ci/g, taking one-eighth of the BG counting rate, 45 cpm, as the limit in this case. Based on the differences between U and Th in geochemical behaviors, it is thought that U is transported into sea water and decays to ^<230>Th which tends to precipitate in the site. From ^<230>Th is produced ^<226>Ra which attains the radioactive equilibrium within a little under ten thousand years. And then, the ^<226>Ra content gradually increases with a half life of 7.5×10^4 years. Therefore, by determining the ratio of Ra in the HClO_4-soluble fraction to that in the Na_2CO_3-fusion fraction of a sample, it is possible to determine its age since the time of sedimentation. The results obtained indicate that the Dry Valley sediment is the oldest while the Lake Stinear sediment is the latest because the ratio is the largest for the former and the smallest for the latter.