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Journal Articles

A Suitable procedure for preparing of water samples used in radiocarbon intercomparison

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:1 Percentile:9.33(Geochemistry & Geophysics)

Water sample for interlaboratory comparison (here after "comparison water") must have inalterable $$^{14}$$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 $$^{14}$$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 $$^{14}$$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 $$^{14}$$C results of CO$$_{2}$$ extracted by six laboratories showed good agreements each other.

Journal Articles

Pre- and post-accident $$^{14}$$C activities in tree rings near the Fukushima Dai-ichi Nuclear Power Plant

Matsunaka, Tetsuya*; Sasa, Kimikazu*; Takahashi, Tsutomu*; Matsumura, Masumi*; Satou, Yukihiko; Shen, H.*; Sueki, Keisuke*; Matsuzaki, Hiroyuki*

Radiocarbon, 61(6), p.1633 - 1642, 2019/12

 Times Cited Count:1 Percentile:9.33(Geochemistry & Geophysics)

Journal Articles

Preliminary test of the EA-AGE3 system for $$^{14}$$C measurement of CaCO$$_{3}$$ samples and coral-based estimation of marine reservoir correction in the Ogasawara Islands, Northwestern Subtropical Pacific

Kokubu, Yoko; Mitsuguchi, Takehiro*; Watanabe, Takahiro; Yamada, Tsutomu*; Asami, Ryuji*; Iryu, Yasufumi*

Radiocarbon, 61(5), p.1593 - 1601, 2019/10

 Times Cited Count:0 Percentile:0.01(Geochemistry & Geophysics)

We performed $$^{14}$$C measurements of two fossil and one modern corals using a combined system of an elemental analyzer and an automated graphitization equipment AGE3 (EA-AGE3 system) and JAEA-AMS-TONO. The $$^{14}$$C concentrations (pMC values) of mid-Holocene Okinawa corals obtained by our EA-AGE3 system appear to be slightly higher than those obtained by the conventional graphitization method using phosphoric acid. The pMC increase in our EA-AGE3 system may result in significant underestimation of $$^{14}$$C age especially for older samples (e.g., 10,000 BP); however, the pMC increase is negligible in $$^{14}$$C measurements of modern or recent samples. We applied the EA-AGE3 method to the pre- and post-bomb annual-band samples from the modern Ogasawara coral for $$^{14}$$C measurements. On the basis of the pre-bomb coral $$^{14}$$C data, we estimated marine reservoir correction ($$Delta$$R) around Ogasawara Islands and its stability between $$sim$$1900 and 1950 AD.

Journal Articles

AMS radiocarbon dates of pyroclastic-flow deposits on the southern slope of the Kuju Volcanic Group, Kyushu, Japan

Okuno, Mitsuru*; Nagaoka, Shinji*; Kokubu, Yoko; Nakamura, Toshio*; Kobayashi, Tetsuo*

Radiocarbon, 59(2), p.483 - 488, 2017/00

 Times Cited Count:3 Percentile:18.21(Geochemistry & Geophysics)

We present here results of AMS $$^{14}$$C dating to refine the history of the middle and western parts of the Kuju Volcanic Group, located in middle Kyushu, Japan, which consists of more than 20 lava domes and cones. $$^{14}$$C dating has conducted by AMS (JAEA-AMS-TONO) under the Common-Use Facility Program of JAEA. The Handa PF deposits, which are products of the largest eruption of the group, were dated to $$sim$$53.5 ka BP. The Shirani and Muro PF deposits, which are block-and-ash flows, were dated to 44 to $$>$$50 cal ka BP and 35$$sim$$39 cal ka BP, respectively. These ages can be correlated with the TL ages for the lava domes. Therefore, both TL and $$^{14}$$C methods can be useful tools in establishing the eruptive sequence of lava domes and pyroclastic flows. This study also demonstrates that these eruptive activities occurred after the Handa pfl, the biggest eruption during the last 150 kyrs without a significant time interval.

Journal Articles

Comparison of $$^{14}$$C collected by precipitation and gas-strip methods for dating groundwater

Nakata, Kotaro*; Hasegawa, Takuma*; Iwatsuki, Teruki; Kato, Toshihiro

Radiocarbon, 58(3), p.491 - 503, 2016/09

AA2015-0781.pdf:0.96MB

 Times Cited Count:4 Percentile:21.4(Geochemistry & Geophysics)

Dissolved inorganic carbon (DIC) for $$^{14}$$C analysis of groundwater is usually extracted by a gas-strip or precipitation method. In this study, the certainty of the two methods for $$^{14}$$C dating were confirmed. DIC and $$^{14}$$C concentrations obtained by the gas-strip method were close to the theoretically predicted $$^{14}$$C value. Conversely, the $$^{14}$$C value obtained by the precipitation method always showed higher values than the predicted values. The difference in $$^{14}$$C value between gas-strip and precipitation methods was assumed to arise owing to contamination of modern carbon used in the precipitation method. The applicability of the precipitation method for groundwater should be considered carefully according to the DIC, $$^{14}$$C concentration of groundwater and purpose of the study being conducted.

Journal Articles

Spatial distribution of $$Delta$$$$^{14}$$C values of organic matter in surface sediments off Saru River in northern Japan, one year after a flood event in 2006

Nagao, Seiya*; Irino, Tomohisa*; Aramaki, Takafumi*; Ikehara, Ken*; Katayama, Hajime*; Otosaka, Shigeyoshi; Uchida, Masao*; Shibata, Yasuyuki*

Radiocarbon, 52(3), p.1068 - 1077, 2010/08

 Times Cited Count:0 Percentile:0.01(Geochemistry & Geophysics)

This study discusses the effects of flooding on the spatial distribution of organic matter on the shelf region of off the Saru River, southern part of Hokkaido, Japan, on the basis of the $$Delta$$$$^{14}$$C and $$delta$$$$^{13}$$C values. Surface sediments on the shelf were collected in August 2007, one year after the severe flood in 2006. Suspended particles and sediment of the Saru River were also collected in August 2007 and 2008. The $$Delta$$$$^{14}$$C values of organic matter in the shelf sediments ranged from -665 to -77 per mil. The silt and clay sediments had $$Delta$$$$^{14}$$C values of -240 to -77 per mil, but the sandy sediments ranged from -665 to -388 per mil. The $$Delta$$ values of particulate organic carbon in the Saru River are -292 to -247 per mil at normal flow conditions. These results indicate that surface soil with relatively older organic matter is deposited on the shelf region by the flooding event, and freshly-produced organic matter in sea surface is deposited after the flooding.

Journal Articles

Circulation in the northern Japan Sea studied chiefly with radiocarbon

Aramaki, Takafumi*; Senju, Tomoharu*; Togawa, Orihiko; Otosaka, Shigeyoshi; Suzuki, Takashi; Kitamura, Toshikatsu; Amano, Hikaru; Volkov, Y. N.*

Radiocarbon, 49(2), p.915 - 924, 2007/10

 Times Cited Count:8 Percentile:25.52(Geochemistry & Geophysics)

no abstracts in English

Journal Articles

Radiocarbon in the water column of the Southwestern North Pacific Ocean; 24 years after GEOSECS

Povinec, P. P.*; Aramaki, Takafumi*; Burr, G. S.*; Jull, A. J. T.*; Liong Wee Kwong, L.*; Togawa, Orihiko

Radiocarbon, 46(2), p.583 - 594, 2004/09

 Times Cited Count:16 Percentile:34.13(Geochemistry & Geophysics)

no abstracts in English

Journal Articles

Distribution of radiocarbon in the southwestern north pacific

Aramaki, Takafumi; Mizushima, Toshihiko; Kuji, Tomoyuki*; Povinec, P. P.*; Togawa, Orihiko

Radiocarbon, 43(2B), p.857 - 867, 2001/03

no abstracts in English

Journal Articles

C-14 application for hydrogeochemical investigation in the Tono Research site, Japan

; ;

Proceedings of 17th International Radiocarbon Conference, P. 164, 2000/00

None

10 (Records 1-10 displayed on this page)
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