1. Changes in radioactive cesium concentrations from 2011 to 2017 in Fukushima coastal sediments and relative contributions of radioactive cesium-bearing microparticles
- Author
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Takashi Ishimaru, Mayumi Otsuki, Atsushi Kubo, Yutaka W. Watanabe, Daisuke Tsumune, Hisayuki Arakawa, Kai Tanabe, Jota Kanda, Hikaru Miura, and Yukari Ito
- Subjects
0106 biological sciences ,Water Pollutants, Radioactive ,010604 marine biology & hydrobiology ,chemistry.chemical_element ,Cesium ,010501 environmental sciences ,Aquatic Science ,Oceanography ,01 natural sciences ,Pollution ,Fukushima daiichi ,Radioactivity ,chemistry ,Japan ,Cesium Radioisotopes ,Radiation Monitoring ,Environmental chemistry ,Caesium ,Nuclear Power Plants ,Environmental science ,Fukushima Nuclear Accident ,Sedimentary rock ,Isotopes of caesium ,0105 earth and related environmental sciences - Abstract
Sedimentary cesium-137 concentrations around the Fukushima Daiichi Nuclear Power Plant (FDNPP) were measured from 2011 to 2017 at eight stations. Although high values were observed until 2013, decreasing trends were observed at the surface sediments of seven stations. We isolated 25 radioactive Cs-bearing microparticles (CsMPs; 1.0–5385 Bq per particle). The contribution ratio of CsMPs to each sample ranged from 4.1% to 99.5% (median 58.8%), with the contribution ratio of the CsMPs in the southern part of the FDNPP was low compared to that from the northern part. In the southern part of the FDNPP, small CsMPs that could not be isolated in this study were present in large quantities immediately after the accident, and gradually diffused away and/or were dissolved over time. In contrast, the CsMPs in the northern part of the FDNPP have most likely accumulated over time, as suggested by the silty nature of the sediments there.
- Published
- 2020