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28 results on '"Yamagata, Takeyasu"'

8. The Link Between the Local Bubble and Radioisotopic Signatures on Earth

Author

Feige, Jenny, Breitschwerdt, Dieter, Wallner, Anton, Schulreich, Michael M., Kinoshita, Norikazu, Paul, Michael, Dettbarn, Christian, Fifield, L. Keith, Golser, Robin, Honda, Maki, Linnemann, Ulf, Matsuzaki, Hiroyuki, Merchel, Silke, Rugel, Georg, Steier, Peter, Tims, Stephen G., Winkler, Stephan R., and Yamagata, Takeyasu

Subjects
Astrophysics - Earth and Planetary Astrophysics, Astrophysics - Solar and Stellar Astrophysics
Abstract

Traces of 2-3 Myr old 60Fe were recently discovered in a manganese crust and in lunar samples. We have found that this signal is extended in time and is present in globally distributed deep-sea archives. A second 6.5-8.7 Myr old signature was revealed in a manganese crust. The existence of the Local Bubble hints to a recent nearby supernova-activity starting 13 Myr ago. With analytical and numerical models generating the Local Bubble, we explain the younger 60Fe-signature and thus link the evolution of the solar neighborhood to terrestrial anomalies., Comment: 4 pages, 3 figures, accepted for publication in JPS Conf. Proc

Published
2016
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23. The Link Between the Local Bubble and Radioisotopic Signatures on Earth

Author

Feige, Jenny, primary, Breitschwerdt, Dieter, additional, Wallner, Anton, additional, Schulreich, Michael M., additional, Kinoshita, Norikazu, additional, Paul, Michael, additional, Dettbarn, Christian, additional, Fifield, L. Keith, additional, Golser, Robin, additional, Honda, Maki, additional, Linnemann, Ulf, additional, Matsuzaki, Hiroyuki, additional, Merchel, Silke, additional, Rugel, Georg, additional, Steier, Peter, additional, Tims, Stephen G., additional, Winkler, Stephan R., additional, and Yamagata, Takeyasu, additional

Published
2017
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24. The Link Between the Local Bubble and Radioisotopic Signatures on Earth

Author

Feige, J., Breitschwerdt, Dieter, Wallner, Anton, Schulreich, Michael M., Kinoshita, Norikazu, Paul, Michael, Dettbarn, C., Fifield, L. Keith, Golser, Robin, Honda, Maki, Linnemann, U., Matsuzaki, Hiroyuki, Merchel, Silke, Rugel, Georg, Steier, Peter, Tims, Stephen, Winkler, S. R., Yamagata, Takeyasu, Feige, J., Breitschwerdt, Dieter, Wallner, Anton, Schulreich, Michael M., Kinoshita, Norikazu, Paul, Michael, Dettbarn, C., Fifield, L. Keith, Golser, Robin, Honda, Maki, Linnemann, U., Matsuzaki, Hiroyuki, Merchel, Silke, Rugel, Georg, Steier, Peter, Tims, Stephen, Winkler, S. R., and Yamagata, Takeyasu

Abstract

Traces of 2-3 Myr old 60Fe were recently discovered in a manganese crust and in lunar samples. We have found that this signal is extended in time and is present in globally distributed deep-sea archives. A second 6.5-8.7 Myr old signature was revealed in a manganese crust. The existence of the Local Bubble hints to a recent nearby supernova-activity starting 13 Myr ago. With analytical and numerical models generating the Local Bubble, we explain the younger 60Fe-signature and thus link the evolution of the solar neighborhood to terrestrial anomalies.

Published
2017

28. Observation of Dispersion in the Japanese Coastal Area of Released 90 Sr, 134 Cs, and 137 Cs from the Fukushima Daiichi Nuclear Power Plant to the Sea in 2013.

Author

Tazoe H, Yamagata T, Tsujita K, Nagai H, Obata H, Tsumune D, Kanda J, and Yamada M

Subjects
Earthquakes, Japan, Cesium Radioisotopes analysis, Fukushima Nuclear Accident, Nuclear Power Plants statistics & numerical data, Radiation Monitoring methods, Seawater analysis, Strontium Radioisotopes analysis, Water Pollutants, Radioactive analysis
Abstract

The March 2011 earthquake and tsunami resulted in significant damage to the Fukushima Daiichi Nuclear Power Plant (FDNPP) and the subsequent release of radionuclides into the ocean. Here, we investigated the spatial distribution of strontium-90 ( 90 Sr) and cesium-134/cesium-137 ( 134, 137 Cs) in surface seawater of the coastal region near the FDNPP. In the coastal region, 90 Sr activity was high, from 0.89 to 29.13 mBq L -1 , with detectable FDNPP site-derived 134 Cs. This indicated that release of 90 Sr from the power plant was ongoing even in May 2013, as was that of 134 Cs and 137 Cs. 90 Sr activities measured at open ocean sites corresponded to background derived from atmospheric nuclear weapons testing fallout. The FDNPP site-derived 90 Sr/ 137 Cs activity ratios in seawater were much higher than those in the direct discharge event in March 2011, in river input, and in seabed sediment; those ratios showed large variability, ranging from 0.16 to 0.64 despite a short sampling period. This FDNPP site-derived 90 Sr/ 137 Cs activity ratio suggests that these radionuclides were mainly derived from stagnant water in the reactor and turbine buildings of the FDNPP, while a different source with a low 90 Sr/ 137 Cs ratio could contribute to and produce the temporal variability of the 90 Sr/ 137 Cs ratio in coastal water. We estimated the release rate of 90 Sr from the power plant as 9.6 ± 6.1 GBq day -1 in May 2013 on the basis of the relationship between 90 Sr and 137 Cs activity ( 90 Sr/ 137 Cs = 0.66 ± 0.05) and 137 Cs release rate.

Published
2019
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