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Misono, Toshiharu; Nakanishi, Takahiro; Shiribiki, Takehiko; Nagao, Seiya*; Ochiai, Shinya*; Sanada, Yukihisa; Tsuruta, Tadahiko
Gekkan Kaiyo, 54(11), p.558 - 561, 2022/11
Sediment traps were set up around estuaries and in coastal areas to collect sinking particles at the time of river discharge. Around the estuary, changes in radiocesium concentration and mass flux of sinking particles linked to the discharge of radiocesium from the river were observed.
Misono, Toshiharu; Tsuruta, Tadahiko; Shiribiki, Takehiko; Nakanishi, Takahiro; Nagao, Seiya*; Ochiai, Shinya*; Sanada, Yukihisa
Journal of Coastal Research, 114(SI), p.315 - 319, 2021/10
Times Cited Count:2 Percentile:16.11(Environmental Sciences)For understanding future radioactive Cs dynamics and its distribution in the coastal area of Fukushima Prefecture, it is important to evaluate the supply of radioactive Cs from river discharge. Especially particulate radioactive Cs supplied in floods might have a significant impact on the coastal area. However, there are few studies on the dynamics of particulate radioactive Cs at the coastal area linked with rivers at the flood event. As a result of measuring the Cs concentration of the sinking particles collected by the sediment trap, at the observation point installed in front of the river, the
Cs concentration collected immediately after the typhoon Bualoi (October 25th) was about higher than before the typhoon. However, the
Cs concentration of the sinking particles collected two days after the typhoon was almost the same as before the typhoon. The impact of rivers on coastal areas during torrential rain stuck is extremely limited.
Watanabe, Takahiro; Ishii, Chikako; Ishizaka, Chika; Niwa, Masakazu; Shimada, Koji; Sawai, Yuki*; Tsuchiya, Noriyoshi*; Matsunaka, Tetsuya*; Ochiai, Shinya*; Nara, Fumiko*
Journal of Mineralogical and Petrological Sciences, 116(3), p.140 - 158, 2021/00
Times Cited Count:5 Percentile:48.09(Mineralogy)A portable energy dispersive X-ray fluorescence spectrometer (potable XRF) can be an effective tool for detecting chemical elements in various materials, such as geological, and environmental samples. In this study, working curves were confirmed using reference materials, such as igneous rocks and other geochemical standards, distributed by national and international organizations. Subsequently, quantification and semi-quantification analyses were performed by the portable XRF for inorganic elements in (A) fault rocks, (B) lake sediments from the middle Japan, and (C) soils with paleotsunami deposits from the Pacific coast of northeast Japan. Twenty-four elements (Mg-U) in these geological samples were measured by potable XRF using our working curves. Measured values by the portable XRF of the samples were good agreement with the reported values in almost cases.
Katsuta, Nagayoshi*; Takano, Masao*; Sano, Naomi; Tani, Yukinori*; Ochiai, Shinya*; Naito, Sayuri*; Murakami, Takuma*; Niwa, Masakazu; Kawakami, Shinichi*
Sedimentology, 66(6), p.2490 - 2510, 2019/10
Times Cited Count:7 Percentile:53.37(Geology)Micro-X-ray fluorescence (XRF) scanning spectroscopy of marine and lake sedimentary sequences can provide detailed paleoenvironmental records available through element intensities proxy data. However, problems for effects of interstitial pore water on the micro-XRF intensities have been pointed out so far because of direct measurement on the split wet sediment surfaces. In this study, new methods for the XRF corrections were developed by being considered with the micro-X-ray scanning spectroscopy.
Katsuta, Nagayoshi*; Ikeda, Hisashi*; Shibata, Kenji*; Kokubu, Yoko; Murakami, Takuma*; Tani, Yukinori*; Takano, Masao*; Nakamura, Toshio*; Tanaka, Atsushi*; Naito, Sayuri*; et al.
Global and Planetary Change, 164, p.11 - 26, 2018/05
Times Cited Count:10 Percentile:42.84(Geography, Physical)Paleoenvironmental and paleoclimate changes in Siberia were reconstructed by continuous, high-resolution records of chemical compositions from a sediment core retrieved from the Buguldeika Saddle, Lake Baikal, dating back to the last 33 cal. ka BP. The Holocene climate followed by a shift at ca. 6.5 cal. ka BP toward warm and dry, suggesting that the climate system transition from the glacial to interglacial state occurred. In the last glacial period, the deposition of carbonate mud from the Primorsky Range was associated with Heinrich events (H3 and H1) and the Selenga River inflow was caused by meltwater of mountain glaciers in the Khamar-Daban Range. The anoxic bottom-water during Allerod-Younger Dryas was probably a result of weakened ventilation associated with reduced Selenga River inflow and microbial decomposition of organic matters from the Primorsky Range. The rapid decline in precipitation during the early Holocene may have been a response to the 8.2 ka cooling event.
Yamasaki, Shinya*; Imoto, Jumpei*; Furuki, Genki*; Ochiai, Asumi*; Onuki, Toshihiko; Sueki, Keisuke*; Namba, Kenji*; Ewing, R. C.*; Utsunomiya, Satoshi*
Science of the Total Environment, 551-552, p.155 - 162, 2016/05
Times Cited Count:32 Percentile:70.56(Environmental Sciences)Cesium-137 (Cs) of estuary sediment impacted by the FDNPP was measured. Increasing radioactivity was observed from surface to bottom. 90% of the
Cs was strongly bound to clay minerals in the estuary sediments. These results suggest that
Cs is being transported from contaminated paddy fields to the estuary.
Kaneko, Makoto*; Iwata, Hajime; Shiotsu, Hiroyuki; Masaki, Shota*; Kawamoto, Yuji*; Yamasaki, Shinya*; Nakamatsu, Yuki*; Imoto, Jumpei*; Furuki, Genki*; Ochiai, Asumi*; et al.
Frontiers in Energy Research (Internet), 3, p.37_1 - 37_10, 2015/09
The mobility of the aggregates of submicron-sized sheet aluminosilicate in the surface environment is a key factor controlling the current Cs migration in Fukushima.
Misono, Toshiharu; Nakanishi, Takahiro; Tsuruta, Tadahiko; Shiribiki, Takehiko; Nagao, Seiya*; Ochiai, Shinya*; Sanada, Yukihisa
no journal, ,
The tsunami caused an accident at the Fukushima Daiichi Nuclear Power Station, causing a large amount of radioactive cesium (RCs) to release and deposit in the surrounding environment. The load of RCs on the coastal area is considered to be resuspension from seafloor sediments and inflow to land through rivers. Quantification of land load is important for understanding the dynamics of RCs. In this study, the RCs concentration and mass flux of sinking particles were measured. We also measured the carbon/nitrogen ratio and stable carbon isotope ratio of sinking particles and attempted to evaluate the effects of land load.
Ochiai, Shinya*; Nagao, Seiya*; Nakanishi, Takahiro; Tsuruta, Tadahiko; Misono, Toshiharu; Watanabe, Shun*; Suzuki, Kyuma*; Tomihara, Seiichi*
no journal, ,
We investigated the controlling factors of radiocesium derived from the nuclear accident in each river systems in Fukushima Prefecture and the surrounding area. Dissolved Cs concentration /
Cs deposition ratio tended to be higher in the Tone River and lower in the Natsui River than in the Abukuma River. Dissolved
Cs concentration generally decreases exponentially, but the half-life is shorter in the Natsui River and longer in the Tone River than in the Abukuma River.
Abe, Tomohisa; Yoshimura, Kazuya; Funaki, Hironori; Nakanishi, Takahiro; Ochiai, Shinya*; Nagao, Seiya*
no journal, ,
no abstracts in English
Abe, Tomohisa; Yoshimura, Kazuya; Funaki, Hironori; Nakanishi, Takahiro; Ochiai, Shinya*; Nagao, Seiya*
no journal, ,
no abstracts in English
Itayama, Yui*; Hayano, Asuka*; Kamegai, Yushi*; Yasuda, Shiori*; Murakami, Takuma*; Ochiai, Shinya*; Niwa, Masakazu; Katsuta, Nagayoshi*
no journal, ,
In this presentation, we report paleo-environmental changes in the southern region of Lake Baikal by chemical and grain-size analyses for the lake sediment cores.
Itayama, Yui*; Masuki, Yuma*; Minami, Masayo*; Ochiai, Shinya*; Yoshimizu, Chikage*; Tayasu, Ichiro*; Niwa, Masakazu; Katsuta, Nagayoshi*
no journal, ,
In this presentation, we report the environmental changes using Buir lake sediments in eastern Mongolian Plateau.