Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Takahashi, Hiroshi*; Minami, Masayo*; Aramaki, Takafumi*; Handa, Hiroko*; Kokubu, Yoko; Ito, Shigeru*; Kumamoto, Yuichiro*
Radiocarbon, 61(6), p.1879 - 1887, 2019/12
Times Cited Count：2 Percentile：11.66(Geochemistry & Geophysics)Water sample for interlaboratory comparison (here after "comparison water") must have inalterable 
C concentration during the comparison campaign and inter-batches homogeneity. In this study, the procedure for preparing of comparison water was discussed. We employed that comparison waters were artificially made by mixing chemical reagents, controlling C concentration and chemical composition. We could prepare six comparison waters, having 1, 14, 37, 56, 72 and 100 pMC, respectively. The stable carbon isotopic values and chemical compositions of some batches were measured to exanimate the inter- batches homogeneity. The C discrepancies among the batches were negligible for the inter-laboratory comparison. Finally, the results of trial comparison in Japan will be presented. Most of C results of CO
extracted by six laboratories showed good agreements each other.
Kumamoto, Yuichiro*; Aramaki, Takafumi*; Watanabe, Shuichi*; Yoneda, Minoru*; Shibata, Yasuyuki*; Togawa, Orihiko; Morita, Masatoshi*; Shitashima, Kiminori*
Journal of Oceanography, 64(3), p.429 - 441, 2008/06
Times Cited Count：11 Percentile：25.5(Oceanography)In 1995 and 2000, radiocarbon ratio (
C) of total dissolved inorganic carbon was measured in the Japan Sea, a semi-closed marginal sea in the western North Pacific, where deep and bottom waters are formed in itself. Compiling them with historical radiocarbon data in the Japan Sea, temporal and spatial variations of the radiocarbon in the bottom water below 2000 m depth were elucidated. C in the bottom waters in the western Japan and Yamato Basins increased by about 20 ‰ between 1977/79 and 1995 and did not changed between 1995 and 1999/2000, suggesting penetration of surface bomb-produced radiocarbon into the bottom waters due to bottom ventilation in the earlier period and stagnation of the bottom ventilation in the following period, respectively. In the eastern Japan Basin, the bottom C increased by about 10 ‰ between 1977/79 and 2002, suggesting less ventilation of the bottom water in the basin. The temporal changes of the radiocarbon, tritium, and dissolved oxygen suggest sporadic occurrences of the bottom ventilation between 1979 and 1984 and its stagnation between 1984 and 2004 in the eastern Japan and Yamato Basins. The former is probably due to spreading of a newly ventilated bottom water in the western Japan Basin in the severe winter of 1976-1977 along the abyssal circulation in the Japan Sea. The latter does not conflict with temporal changes of bomb-produced 
Cs and chlorofluorocarbon-11 in the bottom water.
