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Ota, Masakazu; Tanaka, Taku*
Journal of Environmental Radioactivity, 201, p.5 - 18, 2019/05
Times Cited Count:4 Percentile:16.20(Environmental Sciences)CH
released from deep underground radioactive waste disposal facilities can be a belowground source of
CO
owing to microbial oxidation of
CH
to
CO
in soils. Environmental
C models assume that the transfer of
CO
from soil to plant occurs via foliar uptake of
CO
. Nevertheless, the importance of
CO
root uptake is not well understood. In the present study, belowground transport and oxidation of
CH
were modeled and incorporated into an existing land surface
CO
model (SOLVEG-II) to assess the importance of root uptake on
CO
transfer to plants. Performance of the model in calculating the belowground dynamics of
CH
was validated by simulating a field experiment of
CH
injection into subsoil. The model was then applied to
C transfer in a hypothetical ecosystem impacted by continuous
CH
input from the water table (bottom of one-meter thick soil). In a shallowly rooted ecosystem with rooting depth of 11 cm, foliar uptake of
CO
was significant, accounting for 80% of the
C accumulation in the leaves. In a deeply rooted ecosystem (rooting depth of 97 cm), where the root penetrated to depths close to the water-table, more than half (63%) the
C accumulated in the leaves was transferred by the root uptake. We found that
CO
root uptake in this ecosystem depended on the distribution of methane oxidation in the soil; all
C accumulated in the leaves was transferred by the root uptake when methane oxidation occurred at considerable depths (e-folding depths of 20 cm, or 80 cm). These results indicate that
CO
root uptake contributes significantly to
CO
transfer to plants if
CH
oxidation occurs at great depths and roots penetrate deeply into the soil.
Aramaki, Takafumi*; Togawa, Orihiko; Kitamura, Toshikatsu
Dai-16-Kai Tandemu Kasokuki Oyobi Sono Shuhen Gijutsu No Kenkyukai Hokokushu, p.170 - 172, 2004/02
no abstracts in English
Hamahara, Kazuhiro*; Shigemitsu, Masahito*; Noriki, Shinichiro*; Fukuyama, Ryuji*; Aramaki, Takafumi; Otosaka, Shigeyoshi
Engan Kaiyo Kenkyu, 41(1), p.53 - 60, 2003/08
no abstracts in English
Aramaki, Takafumi; Watanabe, Shuichi*; Kuji, Tomoyuki*
Proceedings of the International Symposium on Atmosphere-Ocean-Cryosphere Interaction in the Sea of Okhotsk and the Surrounding Environment, p.34 - 35, 2001/03
no abstracts in English
Aramaki, Takafumi; Mizushima, Toshihiko; Kuji, Tomoyuki*; Povinec, P. P.*; Togawa, Orihiko
Radiocarbon, 43(2B), p.857 - 867, 2001/03
no abstracts in English
Aramaki, Takafumi; Watanabe, Shuichi*; Tsunogai, Shizuo*; Kuji, Tomoyuki*; Mizushima, Toshihiko; Togawa, Orihiko
JAERI-Conf 2000-019, p.73 - 75, 2001/02
no abstracts in English
Aramaki, Takafumi
JAERI-Research 99-007, 22 Pages, 1999/02
no abstracts in English
Watanabe, Takahiro; Kokubu, Yoko; Fujita, Natsuko; Matsubara, Akihiro*; Nishio, Tomohiro*; Miyake, Masayasu; Kato, Motohisa*; Isozaki, Nobuhiro*; Torazawa, Hitoshi*; Nishizawa, Akimitsu*; et al.
no journal, ,
Radiocarbon dating by Accelerator Mass Spectrometry is widely used for earth and environmental sciences. For high-precision analyses, automatic preparation system and standard methods are needed. The preparation system by elemental analyzer (EA) has been reported. However, we should make clear the changes in background level during the preparation. In this study, we continued radiocarbon dating of international standard materials using the EA at JAEA-AMS-TONO. The radiocarbon concentrations of the standard materials were agreement with the consensus values within 2 sigma.
Wakatsuki, Tsuyoshi*; Yamada, Ryuji*; Kokubu, Yoko
no journal, ,
Many soil slips and debris flows on the welded-tuff slopes were induced by heavy rain on July 28, 2013 in Tsuwano, Shimane. The debris flows eroded sidewalls or streambeds in river channels and the sediments driven by earlier slope movements were exposed in places. In six outcrops, we collected 53 dead wood chip samples presumably buried at the sediment deposition, and radiocarbon dating was performed. At around 418 m asl in Nayoshi district, Tsuwano, the outcrops of the black-clayey sediments are found, which are supposed to have deposited in a past dammed lake. They are distributed at upstream of a topographically-estimated deposit zone for an ancient large-scale slope failure, and the calendar-calibrated ages of these sediments ranges from 41 to 55 ka BP. It is therefore conjectured that the slope failure had occurred before 55 ka BP and the dammed lake had burst after 41 ka BP. An average deposition rate of about 0.3 m/1000 y was estimated at an outcrop of the dammed lake sediments
Hakozaki, Masataka*; Sakamoto, Minoru*; Kokubu, Yoko; Fujita, Natsuko; Li, Z.*; Nakatsuka, Takeshi*
no journal, ,
The sacred tree, a large cedar tree, at the Zinmei Shrine in Mizunami City, Gifu Prefecture was collapsed by heavy rain. Using a part of the tree, we have started measuring its radiocarbon in order to obtain the basic data of calibration curve required for radiocarbon dating. In this presentation, we report the result of age determination of the tree.
Tsukahara, Yuzuko; Saito, Toshihito*; Nakanishi, Toshimichi*; Nishiyama, Nariaki; Fujita, Natsuko; Kawamura, Makoto; Umeda, Koji*
no journal, ,
Paleo-sea levels estimated from the elevation and age of emerged shoreline features and fossil calcareous assemblages are one of the useful tools for reconstructing the tectonic features of the Holocene. In this study, we reconstruct the paleo-sea levels around the eastern part of Izu Peninsula using fossil calcareous assemblages to verify case studies in areas with active volcanism and seismic activity. In addition, we will infer the characteristics of crustal deformation through comparison with previous studies. Shishikura et al. (2023) surveyed emerged shoreline features and fossil calcareous assemblages around the coast in the vicinity of Ito, the northeastern part of the Izu Peninsula, to clarify the emerged process. They concluded that the cause of the emergence is associated with a volcanotectonic uplift due to subsurface magma movement. In order to verify the representativeness of this crustal feature, we conducted a field survey of the Jogasaki Coast, 89 km south of the area studied by Shishikura et al. (2023). We found four fossil calcareous assemblages at three sites on the Jogasaki Coast, and dated them to 1356
1470 CE using the
C. Fossil assemblages with similar ages have been reported by Shishikura et al. (2023), but the elevation in this study is about 1 m higher. This difference may suggest a spatial variation in tectonic features in this area.
Yasue, Kenichi; Hirouchi, Daisuke*; Matsubara, Akihiro; Kokubu, Yoko
no journal, ,
no abstracts in English
Jeon, H.; Ogawa, Hiroshi*; Otosaka, Shigeyoshi
no journal, ,
Radiocarbon content of marine dissolved organic carbon (DOC) can provide useful information on how organic carbon is produced, transported, and ultimately sequestered in the ocean interior. We conducted research to present the first set of full-depth profiles for DO
C along a transect from the central South Pacific Ocean to Chukchi Sea. In order to measure radiocarbon contents of seawater samples, they should be processed with a specific preparation system consists of the custom quartz reactor, dedicated vacuum line and UV lamp followed by radiocarbon counting with an accelerator mass spectrometer. As the first step of the study, we have developed the irradiation procedure using a low-pressure Hg lamp and an oxidation catalyst. We present here how the system is progressing as well as what radiocarbon study in the central Pacific Ocean means for better understanding of oceanic carbon cycle.
Jeon, H.; Otosaka, Shigeyoshi; Yamashita, Yohei*; Ogawa, Hiroshi*
no journal, ,
The ocean is a huge reservoir of dissolved organic carbon that contains almost the same amount of carbon in the atmosphere. Radiocarbon signatures of dissolved organic carbon (DOC) in seawater can provide useful information on how organic carbon is produced, transported, and ultimately sequestered in the ocean's interior. In order to measure radiocarbon contents of seawater samples, they should be processed with a specific preparation system consists of the custom quartz reactor, dedicated vacuum line and UV lamp followed by radiocarbon counting with an accelerator mass spectrometer. As the first step of the study, we developed the irradiation procedure using a low-pressure Hg lamp and an oxidation catalyst. We present here not only how the system is progressing but also what radiocarbon study in the central Pacific Ocean means for better understanding of oceanic carbon cycle.
Jeon, H.; Otosaka, Shigeyoshi; Yamashita, Yohei*; Ogawa, Hiroshi*
no journal, ,
Measurements of the radiocarbon content of marine dissolved organic carbon (DOC) broadened our perspective on the role of DOC in the marine carbon cycle. However fewer measurements have been performed because of methodological difficulties associated with low concentration of DOC and an overwhelming proportion of salts. In order to collect enough DOC for radiocarbon analysis, UV oxidation is one of the most commonly used methods by irradiating seawater samples with ultraviolet light. Unlike other studies where medium pressure mercury arc UV lamp are used, this study attempts to improve the system with two grid lamps in order to reduce the demand for high electric power installation and to miniaturize the instrument for easier handling. We aim to verify the performance of improved equipment by processing
C reference materials as well as seawater samples.
Nagai, Haruyasu; Koarashi, Jun; Atarashi-Andoh, Mariko; Ota, Masakazu; Nagano, Hirohiko
no journal, ,
no abstracts in English
Yamada, Rena*; Ikemori, Fumikazu*; Nakamura, Toshio*; Minami, Masayo*; Watanabe, Takahiro; Kinouchi, Kento*; Matsuki, Atsushi*
no journal, ,
Aerosols and clouds seeded by them both affect the heat budget of the Earth, but their RF (radiative forcing) still involves large uncertainty (IPCC 2013). One of the least understood properties of aerosols is the source and contribution of the organics. Our recent observation revealed that submicron aerosol particles in Noto peninsula also have a relatively high concentration (approximately more than 50%) of carbonaceous matter throughout the year. It is difficult to presume its sources specifying its chemical species in many scenes because of its great variety. However, we can presume its source by using carbon isotope ratio. We conducted sampling in NOTOGRO (NOTO ground-based research observatory), lying at the edge of Noto peninsula, from 26th Jun to 23rd July, 2014. We corrected PM using high volume air sampler for every week. Flow rate was 700L/min, and quartz fiber filter was used for sampling.
C was analyzed using AMS
C system (High Voltage Engineering Europe, Model 4130-AMS) and
C using IRMS (isotope ratio mass spectrometer) in Nagoya University. As a result, it was found that 4 samples collected from 26th Jun to 23rd July had approximately 70 percent modern carbon (pMC). This result shows that modern plant (and/or biomass burning) activities mainly contribute to the submicron organic particle concentration in Noto peninsula.
Yasue, Kenichi*; Harada, Shunsuke*; Kokubu, Yoko; Hirouchi, Daisuke*
no journal, ,
We present the results of a pit survey conducted in the middle part of the Atera fault zone and C dating of black soil. Samples were collected continuously from the black soil on both sides of the fault at intervals of approximately 5 cm in the depth direction. The dating sample was treated with hydrochloric acid and sodium hydroxide and separated into an alkali-soluble component (humic acid) and an insoluble component (humin). As a result of the dating, the age values generally become younger from the bottom to the surface. In detail, we can see parts where the age gradually become younger towards the surface, parts where the age are almost the same continuously, and parts where the age are reversed. The parts where the age gradually decreases toward the surface is considered to be a normal forest condition where black soil gradually forms over time. A succession of the same age values suggests the formation of a rapid deposition field. The age reversal suggests that older black soil was redeposited on top. These results indicate some event. For example, it is possible that old black soil was rapidly supplied from the upper layer after the fault displacement. We must carefully consider the type of event.
Yamada, Ryuji*; Kokubu, Yoko; Wakatsuki, Tsuyoshi*; Yasue, Kenichi
no journal, ,
Mass movements and fault movements are natural phenomena to change the local topography. Reconstruction of the movement histories and evaluation of long-term stability of topographies are crucial to assess the geological environment in future. History reconstruction based on radiocabon dating of plant material recovered from sediment deposited by the past movements requires the compilation and the comparison of existing data measured by different analysts with different methods. We compared the results of radiocarbon ages measured at different laboratories with various chemical pretreatments, using plant material samples. For older samples (about 45000 BP), dispersion in ages is greater than measurement uncertainty. However the order of weighted mean ages for each sample agrees well with stratigraphic sequence at the sampling site. It is therefore thought that the influence of the systematic error due to a specific experimental conditions is small.