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Alam, M. M.*; Yamakita, Eri*; Inoue, Yuzuru*; Koarashi, Jun; Atarashi-Andoh, Mariko; Abe, Yukiko; Nakayama, Hiromasa; Mori, Yuki*; Hiradate, Shuntaro*
Soil Science and Plant Nutrition, 72(1), p.55 - 66, 2026/01
Alam, M. M.*; Yamakita, Eri*; Tamanna, S.*; Thae, E. P.*; Koarashi, Jun; Atarashi-Andoh, Mariko; Abe, Yukiko; Nakayama, Masataka; Mori, Yuki*; Hiradate, Shuntaro*
Soil Science and Plant Nutrition, 12 Pages, 2026/00
Abe, Yukiko; Nakayama, Masataka*; Atarashi-Andoh, Mariko; Tange, Takeshi*; Sawada, Haruo*; Liang, N.*; Koarashi, Jun
Geoderma, 455, p.117221_1 - 117221_11, 2025/03
Times Cited Count：0 Percentile：0.00(Soil Science)Subsoils (typically below a depth of 30 cm) contain more than half of global soil carbon (C) as soil organic C (SOC). However, the extent to which subsoil SOC contributes to the global C cycle and the factors that control it are unclear because quantitative evaluation of carbon dioxide (CO
) emission from subsoils through direct observations is limited. This study aimed to quantify CO emission from subsoils and determine factors that control CO emission, focusing on the decomposability of soil organic matter (SOM) and the characteristics of the mineral-SOM association in soils. Therefore, a laboratory incubation experiment was conducted using surface soils (0-10 cm and 10-25 cm depth) and subsoils (30-45 cm and 45-60 cm depth) collected from four Japanese forest sites with two different soil types (volcanic ash and non-volcanic ash soils). The CO emission from the subsoils was found to be responsible for 6%-23% of total CO emission from the upper 60-cm mineral soil across all sites. Radiocarbon signatures of CO released from the subsoils indicated the decomposition of decades-old SOM in the subsoils. The correlations between CO emission rate and soil factors across both soil types suggested that the CO emission from the subsoils is mainly controlled by the amounts of SOC easily available to soil microbes and microbial biomass C, not by the amounts of reactive minerals. Given the potential active participation of subsoils in terrestrial C cycling, most of the current soil C models that ignore subsoil C cycling are likely to underestimate the response of soil C to future climate change. The quantitative and mechanistic understanding of C cycling through a huge subsoil C pool is critical to accurately evaluating the role of soil C in the global C balance.
Nakayama, Masataka; Abe, Yukiko; Atarashi-Andoh, Mariko; Tange, Takeshi*; Sawada, Haruo*; Liang, N.*; Koarashi, Jun
Applied Soil Ecology, 201, p.105485_1 - 105485_12, 2024/09
Times Cited Count：4 Percentile：56.38(Soil Science)Nitrogen often limits plant growth in forest ecosystems. Plants, including trees, change vertical root distribution when nutrient competition is strong within surface soil layer and take up nitrogen even from subsurface soil layers in addition to the surface soil. However, there is still limited knowledge about nitrogen cycles within deeper soil layers. In this study, we investigated the vertical profiles (0-60 cm) of the net nitrogen mineralization and nitrification rates at four Japanese forest sites with two different soil types (Andosols and Cambisols). The partial least square path modeling (PLS-PM) was used to determine factors affecting nitrogen-cycling processes. The net nitrogen mineralization and nitrification rates per unit soil weight were considerably higher in surface soil layer than in deeper soil layers in Andosols but not in Cambisols. PLS-PM analysis showed that microbial biomass and soil organic matter quantities were the main factors influencing the net nitrogen mineralization and nitrification rates, indicating that a similar mechanism creating the spatial variations of nitrogen-cycling processes in surface soil layer predominantly regulates the processes in subsoil layers. Moreover, it was estimated that the net nitrogen mineralization rate could be comparable at all soil types and depths when the rate was expressed per unit soil volume. Therefore, our results suggest that subsoil layers are a quantitatively important nitrogen source for plant nutrients in Andosols and Cambisols, supporting high forest productivity.
plantationAbe, Yukiko*; Liang, N.*; Teramoto, Munemasa*; Koarashi, Jun; Atarashi-Andoh, Mariko; Hashimoto, Shoji*; Tange, Takeshi*
Geoderma Regional (Internet), 29, p.e00529_1 - e00529_11, 2022/06
Times Cited Count：4 Percentile：21.64(Soil Science)This study aimed to clarify the causes of spatial variation in soil respiration rate on volcanic ash soil. From January 2013 to August 2019, soil respiration rates were measured at 40 measuring points periodically at a 35-year-old plantation in Tokyo, Japan. In August 2019, the carbon content of the litter layer, total carbon content of soil organic matter (SOM), carbon content of the low-density fraction (LF-C) of SOM, fine root biomass, and bulk density of soil were measured at all measuring points. Results of the multiple regression analysis showed that the model with only the LF-C as an explanatory variable had the highest capability for predicting the respiration rate at a soil temperature of 20
C, indicating that LF-C, which is considered to be readily available to soil microorganisms, can be the main factor responsible for the spatial variation in soil respiration rate.
Tanaka, Taiki*; Narikiyo, Yoshihiro*; Morita, Kosuke*; Fujita, Kunihiro*; Kaji, Daiya*; Morimoto, Koji*; Yamaki, Sayaka*; Wakabayashi, Yasuo*; Tanaka, Kengo*; Takeyama, Mirei*; et al.
Journal of the Physical Society of Japan, 87(1), p.014201_1 - 014201_9, 2018/01
Times Cited Count：25 Percentile：77.91(Physics, Multidisciplinary)Excitation functions of quasielastic scattering cross sections for the 
Ca + 
Pb, 
Ti + Pb, and Ca + 
Cm reactions were successfully measured by using the gas-filled recoil-ion separator GARIS. Fusion barrier distributions were extracted from these data, and compared with the coupled-channels calculations. It was found that the peak energies of the barrier distributions for the Ca + Pb and Ti + Pb systems coincide with those of the 2n evaporation channel cross sections for the systems, while that of the Ca + Cm is located slightly below the 4n evaporation ones. This results provide us helpful information to predict the optimum beam energy to synthesize superheavy nuclei.
Hidaka, Akihide; Nakamura, Kazuyuki; Watanabe, Yoko; Yabuuchi, Yukiko; Arai, Nobuyoshi; Sawada, Makoto; Yamashita, Kiyonobu; Sawai, Tomotsugu; Murakami, Hiroyuki
Proceedings of 23rd International Conference on Nuclear Engineering (ICONE-23) (DVD-ROM), 9 Pages, 2015/05
Hanzawa, Yukiko; Magara, Masaaki; Watanabe, Kazuo; Esaka, Fumitaka; Miyamoto, Yutaka; Yasuda, Kenichiro; Gunji, Katsubumi*; Yamamoto, Yoichi; Takahashi, Tsukasa; Sakurai, Satoshi; et al.
JAERI-Tech 2002-103, 141 Pages, 2003/02
JAERI-Tech-2002-103.pdf:10.38MB
The JAERI has established a facility with a cleanroom: the Clean Laboratory for Environmental Analysis and Research (CLEAR). This report is an overview of the design, construction and performance evaluation of the CLEAR in the initial stage of the laboratory operation in June 2001. The CLEAR is a facility to be used for ultra trace analyses of nuclear materials in environmental samples for the safeguards, for the CTBT verification and for researches on environmental sciences. The CLEAR meets double requirements of a cleanroom and for handling of nuclear materials. Much attention was paid to the construction materials of the cleanroom for trace analysis of metal elements using corrosive acids. The air conditioning and purification system, experimental equipment, utilities and safety systems are also demonstrated. The potential contamination from the completed cleanroom atmosphere during the analytical procedure was evaluated. It can be concluded that the CLEAR has provided a suitable condition for reliable analysis of ultra trace amounts of nuclear materials in environmental samples.
Hanzawa, Yukiko; Magara, Masaaki; Watanabe, Kazuo; Esaka, Fumitaka; Miyamoto, Yutaka; Yasuda, Kenichiro; Gunji, Katsubumi*; Sakurai, Satoshi; Takano, Seinojo*; Usuda, Shigekazu; et al.
Journal of Nuclear Science and Technology, 40(1), p.49 - 56, 2003/01
Times Cited Count：4 Percentile：30.76(Nuclear Science & Technology)The JAERI has established a cleanroom facility with cleanliness of ISO Class 5: the Clean Laboratory for Environmental Analysis and Research (CLEAR). It was designed to be used for the analysis of nuclear materials in environmental samples for the safeguards, the Comprehensive Nuclear-Test-Ban Treaty verification and research on environmental sciences. The CLEAR facility was designed to meet double conflicting requirements of a cleanroom and for handling of nuclear materials according to Japanese regulations, i.e., to avoid contamination from outside and to contain nuclear materials inside the facility. This facility has been intended to be used for wet chemical treatment, instrumental analysis and particle handling. A fume-hood to provide a clean work surface for handling of nuclear materials was specially designed. The performance of the cleanroom and analytical background in the laboratory are discussed. It can be concluded that the CLEAR facility enables analysis of ultra trace amounts of nuclear materials at the sub-picogram level in environmental samples.
Takahashi, Masato; Magara, Masaaki; Sakurai, Satoshi; Kurosawa, Setsumi; Sakakibara, Takaaki; Hanzawa, Yukiko; Esaka, Fumitaka; Watanabe, Kazuo; Usuda, Shigekazu; Adachi, Takeo
Journal of Nuclear Science and Technology, 39(Suppl.3), p.568 - 571, 2002/11
In the environmental sampling and analyses for safeguards, precise isotope ratio determination of uranium at trace levels is required for detection of undeclared nuclear activities. Currently, swipe samples are being taken by IAEA from the nuclear facilities. The amount of uranium collected on the cotton swipe is expected to be in the wide range including the order of nano-gram or less. In order to measure the isotope ratios by ICP-MS, we have studied sample preparation procedures. Four pretreatments of swipe samples were examined: 1) nitric acid leaching, 2) dry ashing, 3) low-temperature plasma ashing, and 4) acid digestion. Preliminary results showed that the combination of 3) and 4) was favorable from the points of uranium blank, cross-contamination, chemical yield and manipulation conditions in a clean laboratory. It was found that the cotton swipe contained nano-gram levels of uranium as impurity. Since this value may seriously interfere with the isotopic analysis of uranium, selective recovery of the deposited uranium by means of mechanical method is also studied.
Magara, Masaaki; Sakakibara, Takaaki; Kurosawa, Setsumi; Takahashi, Masato; Sakurai, Satoshi; Hanzawa, Yukiko; Esaka, Fumitaka; Watanabe, Kazuo; Usuda, Shigekazu
Journal of Analytical Atomic Spectrometry, 17(9), p.1157 - 1160, 2002/09
Times Cited Count：11 Percentile：43.18(Chemistry, Analytical)no abstracts in English
Sakurai, Satoshi; Hanzawa, Yukiko; Magara, Masaaki; Usuda, Shigekazu; Watanabe, Kazuo; Adachi, Takeo
Kuki Seijo, 39(6), p.404 - 410, 2002/03
no abstracts in English
Esaka, Fumitaka; Magara, Masaaki; Hanzawa, Yukiko; Sakurai, Satoshi; Taguchi, Takuji; Takai, Konomi; Sakakibara, Takaaki; Kurosawa, Setsumi; Takahashi, Masato; Yasuda, Kenichiro; et al.
Dai-22-Kai Kaku Busshitsu Kanri Gakkai Nihon Shibu Nenji Taikai Rombunshu, 8 Pages, 2001/11
no abstracts in English
Esaka, Fumitaka; Watanabe, Kazuo; Magara, Masaaki; Hanzawa, Yukiko; Usuda, Shigekazu
Journal of Trace and Microprobe Techniques, 19(4), p.487 - 496, 2001/11
Times Cited Count：9 Percentile：29.44(Chemistry, Analytical)The capability of total-reflection X-ray fluorescence spectrometry (TXRF) technique was studied to screen a swipe sample for uranium content, which was employed to decide on the further isotopic ratio measurements by secondary ion mass spectrometry (SIMS) for safeguards environmental sample analysis. A part of the measurement system of TXRF was modified to be able to use the same glassy carbon carrier for SIMS analysis. Particles in the swipe sample were recovered on the carbon carrier. The relative sensitivities of 11 elements including uranium were determined using selenium as an internal standard. The detection limit of uranium was 0.4 ng. The screening technique studied was applied to the practical swipe samples taken from the laboratories. The results confirm that TXRF can be a promising screening technique for uranium in swipe samples for safeguards environmental sample analysis.
Usuda, Shigekazu; Watanabe, Kazuo; Sakurai, Satoshi; Magara, Masaaki; Hanzawa, Yukiko; Esaka, Fumitaka; Miyamoto, Yutaka; Yasuda, Kenichiro; Saito, Yoko; Gunji, Katsubumi*; et al.
KEK Proceedings 2001-14, p.88 - 92, 2001/06
no abstracts in English
Esaka, Fumitaka; Zheng, W.*; Watanabe, Kazuo; Magara, Masaaki; Hanzawa, Yukiko; Usuda, Shigekazu; Adachi, Takeo
Advances in Mass Spectrometry, 15, p.973 - 974, 2001/00
no abstracts in English
Adachi, Takeo; Usuda, Shigekazu; Watanabe, Kazuo; Sakurai, Satoshi; Magara, Masaaki; Hanzawa, Yukiko; Esaka, Fumitaka; Yasuda, Kenichiro; Saito, Yoko; Takahashi, Masato; et al.
IAEA-SM-367/10/02 (CD-ROM), 8 Pages, 2001/00
no abstracts in English
Magara, Masaaki; Hanzawa, Yukiko; Esaka, Fumitaka; Miyamoto, Yutaka; Yasuda, Kenichiro; Watanabe, Kazuo; Usuda, Shigekazu; Nishimura, Hideo; Adachi, Takeo
Applied Radiation and Isotopes, 53(1-2), p.87 - 90, 2000/07
Times Cited Count：28 Percentile：83.34(Chemistry, Inorganic & Nuclear)no abstracts in English
Nishimura, Hideo; Magara, Masaaki; Hanzawa, Yukiko; Esaka, Fumitaka; Takahashi, Tsukasa; Gunji, Katsubumi; Miyamoto, Yutaka; Yasuda, Kenichiro; Tsuruta, Yasuhiro; Tsuda, Shinji; et al.
Heisei 11-Nendo Hosho Sochi Semina Koenroku Tekisuto, p.95 - 107, 2000/01
no abstracts in English
Esaka, Fumitaka; Watanabe, Kazuo; Magara, Masaaki; Hanzawa, Yukiko; Usuda, Shigekazu; Gunji, Katsubumi; Nishimura, Hideo; Adachi, Takeo
Proceedings of 12th International Conference on Secondary Ion Mass Spectrometry (SIMS 12), p.977 - 980, 2000/00
no abstracts in English
