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Distributions and temporal variation of radiocaesium in surface waters collected from the western north Pacific after the accident of TEPCO’s Fukushima Dai-ichi Nuclear power Stations
https://repo.qst.go.jp/records/71491
https://repo.qst.go.jp/records/714917c184f4e-acf7-460d-83d5-a80f3070e2ea
| Item type | 会議発表用資料 / Presentation(1) | |||||
|---|---|---|---|---|---|---|
| 公開日 | 2014-09-18 | |||||
| タイトル | ||||||
| タイトル | Distributions and temporal variation of radiocaesium in surface waters collected from the western north Pacific after the accident of TEPCO’s Fukushima Dai-ichi Nuclear power Stations | |||||
| 言語 | ||||||
| 言語 | eng | |||||
| 資源タイプ | ||||||
| 資源タイプ識別子 | http://purl.org/coar/resource_type/c_c94f | |||||
| 資源タイプ | conference object | |||||
| アクセス権 | ||||||
| アクセス権 | metadata only access | |||||
| アクセス権URI | http://purl.org/coar/access_right/c_14cb | |||||
| 著者 |
福田, 美保
× 福田, 美保× 青野, 辰雄× 山崎, 慎之介× 吉田, 聡× 本多, 牧生× 川上, 創× 才野, 敏郎× 福田 美保× 青野 辰雄× 吉田 聡 |
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| 抄録 | ||||||
| 内容記述タイプ | Abstract | |||||
| 内容記述 | The 2011 off the Pacific coast of Tohoku Earthquake and tsunami on March 11, 2011 have led to the accident of TEPCO’s Fukushima Dai-ich Nuclear Power Station (FNPS) and large amount of radioactive material were discharged by the hydrogen explosion and leaked from FNPS to the ocean. The reports have been described that the released 137Cs to atmosphere from FNPS were estimated from 13 to 50 PBq and estimates of 137Cs derived from direct discharge to the ocean range from about 3 to 40 PBq. However, the transport and diffusion of radiocaesium in the ocean is still insufficiently understood after this accident. To improve the accuracy of the diffusion simulation in the ocean, more data are required from many regions including offshore regarding temporal changes and long term. The aim of this study was to elucidate the variation and behavior of 134Cs and 137Cs activities in western north Pacific. During four cruises (MR11-03；from 15 April to 5 May 2011, MR11-05；from 27 June to 4 August 2011, MR12-02；from 4 June to 12 July 2012 and MR13-04；from 10 July to 29 July 2013), seawater samples were collected from surface to 400 m water depth along the cruise track with an underway surface pump and a multiple water-sampling system, analyed by the ammonium phosphomolybdate/Cs compound method (Aoyama and Hirose, 2008) and then measured activity of Cs using low back ground gamma spectrometry using Ge detectors. Activities of 134Cs (Bq kg-1) caused by the accident in surface water ranged from 0.004 to 0.27, from 0.12 to 0.75, and from 0.0011 to 0.01 during MR11-03, MR11-05 and MR12-02 cruise, respectively. About one month later from the accident, samples from stations off Fukushima and off Miyagi had higher 134Cs and 137Cs than those at other stations and the highest activities of 137Cs were about 140 times higher than the average value before the accident (0.002 Bq kg-1 in the 2000s). Average activities of 134Cs and 137Cs about three months later after the accident, were about two times higher than those of one month later from the accident. On the other hands, average activities of 134Cs and 137Cs about a year later after the accident decreased about 5 % value of about three month after the accident. Radiocaecium activities in seawater were generally highest in the surface water throughout three cruise and most station, but 137Cs activity at the S1 site (30° N, 145° E) about a year later after the accident, observed maximum layer in about 150 m water depth. It is considered that these results were caused by not only diffusion but also the subduction of seawater. In this presentation, we will also report the variation and behavior of 134Cs and 137Cs activities in seawater collected in MR13-04 cruise. |
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| 会議概要（会議名, 開催地, 会期, 主催者等） | ||||||
| 内容記述タイプ | Other | |||||
| 内容記述 | ICRER 2014 - Third International Conference on Radioecology and Environmental Radioactivity | |||||
| 発表年月日 | ||||||
| 日付 | 2014-09-10 | |||||
| 日付タイプ | Issued | |||||
