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Nagano, Hirohiko*; Atarashi-Andoh, Mariko; Tanaka, Sota*; Yomogida, Takumi; Kozai, Naofumi; Koarashi, Jun
Frontiers in Forests and Global Change (Internet), 6, p.1228053_1 - 1228053_9, 2023/00
Times Cited Count:0 Percentile:0.01(Ecology)Tanaka, Sota; Kakinuma, Hotaru*; Adachi, Taro*; Atarashi-Andoh, Mariko; Koarashi, Jun
Journal of Nuclear Science and Technology, 58(4), p.507 - 514, 2021/04
Times Cited Count:0 Percentile:0.01(Nuclear Science & Technology)Understanding the pathways of Cs transfer to predatory spiders is useful to assess long-term behavior of Cs in the environment, because spiders obtain food resources from both the grazing and detritus food chains in terrestrial-aquatic linking forest ecosystems. In the present study, we collected spider samples at forest interior and riverside. The sample collection was approximately 6.5 years after the FDNPP accident. Moreover, a transfer factor value (T) for Cs in spiders was quantified. Stable carbon and nitrogen isotope ratios (C and N) of the spiders were also investigated to estimate the transfer pathways of Cs to the spiders.
Tanaka, Sota; Kinouchi, Tadatoshi*; Fujii, Tsuguru*; Imanaka, Tetsuji*; Takahashi, Tomoyuki*; Fukutani, Satoshi*; Maki, Daisuke*; Notomi, Akihiro*; Takahashi, Sentaro*
Scientific Reports (Internet), 10, p.16055_1 - 16055_7, 2020/09
Times Cited Count:7 Percentile:53.13(Multidisciplinary Sciences)Since the Fukushima Dai-ichi Nuclear Power Plant (FDNPP) accident, morphological abnormalities of the lepidopteran insects have been reported. However, it is unclear whether the abnormalities were caused directly by radiation because they did not study on absorbed dose and dose-effect relationship. In this study, we conducted an internal exposure experiment on silkworm using CsCl-supplemented artificial diet and estimated the absorbed dose to evaluate the morphological abnormalities in silkworm. The ratio of wing to whole body of pupae was compared between the CsCl-exposured and control groups and no significant differences were observed between the groups. This result suggest that morphological abnormalities in lepidopterans are unlikely due to direct radiation effects from Cs contamination after the FDNPP accident.
Tanaka, Sota; Adachi, Taro*; Takahashi, Tomoyuki*; Takahashi, Sentaro*
Low-Dose Radiation Effects on Animals and Ecosystems; Long-Term Study on the Fukushima Nuclear Accident, p.43 - 52, 2020/00
Times Cited Count:1 Percentile:11.8(Ecology)To understand the behavior of radiocesium in terrestrial invertebrates, chronological changes in the concentration of radiocesium in arthropods and earthworms from different trophic levels were investigated after the Fukushima Daiichi Nuclear Power Plant accident. The median radiocesium concentrations in the rice grasshopper, Oxya yezoensis, and the Emma field cricket, Teleogryllus emma, were 0.46 and 0.15 Bq/g fw in 2012, respectively, which dropped continuously to 0.05 and 0.01 Bq/g fw in 2016. In contrast, no significant reduction in radiocesium concentration was observed in the Joro Spider, Nephila clavata, in which the concentration was 0.31 Bq/g fw in 2012 and remained at 0.14 Bq/g fw in 2016. The comparison of radiocesium concentrations at each trophic level showed that the amount in detritivorous earthworms was 85 times higher than in herbivorous grasshoppers. This suggests that detritus food web could be a primary pathway of radiocesium through food webs.
Tanaka, Sota; Kakinuma, Hotaru*; Adachi, Taro*; Takahashi, Tomoyuki*; Takahashi, Sentaro*
KEK Proceedings 2019-2, p.179 - 182, 2019/11
The concentration of Cs in flying insects was investigated after the Fukushima Dai-ichi Nuclear Power Plant (FDNPP) accident. The insects were collected at about 11 km north west of the FDNPP at two different sites in the forest and riverside. The median concentration of Cs in flying insects in the forest was significantly higher than riverside. However, high concentration of Cs in detritus fly (Diptera: Calliphoridae) was observed at both sites. The concentration of fly at the forest and riverside were 1610 Bq/kg fw and 1810 Bq/kg fw, respectively. The result shows that the concentration of radiocesium in detritus fly were still high 8 years after the accident. This suggests that detritus food chain is a dominant transfer pathway of radiocesium to higher trophic level species such as spiders.
Takahashi, Sentaro*; Kawashima, Shigeto*; Hidaka, Akihide; Tanaka, Sota*; Takahashi, Tomoyuki*
Nuclear Technology, 205(5), p.646 - 654, 2019/05
Times Cited Count:4 Percentile:40.43(Nuclear Science & Technology)Tanaka, Sota; Atarashi-Andoh, Mariko; Koarashi, Jun
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Tanaka, Sota; Adachi, Taro*; Takahashi, Tomoyuki*; Takahashi, Sentaro*
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Tanaka, Sota; Kakinuma, Hotaru*; Adachi, Taro*; Atarashi-Andoh, Mariko; Koarashi, Jun
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Terrestrial arthropods could be an indicator species of long-term behavior of radiocesium through the food chain due to their large biomass and importance as food resources for other organisms. The spider, Nephila clavata, as generalist predators is especially suggested that an indicator species of radiocesium contamination of insect communities because they prey on variety of food resources from both grazing and detrital food chain. In present study, the aggregated transfer factor (T) of Cs for the spiders inhabited at mountainous forest and riverside was calculated using the initial deposition densities map, and stable isotope ratio(C, N) of the spider was measured to determine the transfer pathway of Cs.
Tanaka, Sota; Nagano, Hirohiko; Atarashi-Andoh, Mariko; Koarashi, Jun
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Nagano, Hirohiko; Tanaka, Sota; Atarashi-Andoh, Mariko; Koarashi, Jun
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Soil organic carbon (SOC) is a key component in global carbon cycling, while water-extractable organic carbon (WEOC) in soils is a proxy of soil carbon available to the living microbial community. Volcanic ash soils, a soil type dominant in Japan, are known to have a very high ability to stabilize soil carbon, and SOC content often correlates with phosphate absorption coefficients (PAC) in soils. In this study, we compared the SOC-PAC relationship and the WEOC-PAC relationships using 42 volcanic ash soils (0-6 cm depth) collected from a Japanese temperate forest. SOC showed a very strong correlation with PAC (r = 0.72). Correlation between SOC and WEOC was also strong (r = 0.84). Correlation between WEOC and PAC was, however, weak (r = 0.42). Thus, water destabilized carbon likely originated from residual carbon sources other than the primary carbon that is highly stabilized in volcanic ash soils.
Tanaka, Sota; Nagano, Hirohiko*; Atarashi-Andoh, Mariko; Koarashi, Jun
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Nagano, Hirohiko*; Atarashi-Andoh, Mariko; Tanaka, Sota*; Koarashi, Jun
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Nagano, Hirohiko*; Atarashi-Andoh, Mariko; Tanaka, Sota*; Hiradate, Shuntaro*; Fujii, Kazumichi*; Koarashi, Jun
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Nagano, Hirohiko*; Tanaka, Sota*; Atarashi-Andoh, Mariko; Koarashi, Jun
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no abstracts in English
Tanaka, Sota*; Nagano, Hirohiko*; Atarashi-Andoh, Mariko; Takakai, Fumiaki*; Sato, Takashi*; Koarashi, Jun
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no abstracts in English