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240Pu/239Pu atom ratios in water columns from the North Pacific Oceanand Bering Sea: Transport of Pacific Proving Ground-derived Pu by Ocean Currents
https://repo.qst.go.jp/records/79710
https://repo.qst.go.jp/records/797109bc518a2-5dc8-46c5-a52d-ae4239e713aa
| Item type | 学術雑誌論文 / Journal Article(1) | |||||
|---|---|---|---|---|---|---|
| 公開日 | 2019-11-19 | |||||
| タイトル | ||||||
| タイトル | 240Pu/239Pu atom ratios in water columns from the North Pacific Oceanand Bering Sea: Transport of Pacific Proving Ground-derived Pu by Ocean Currents | |||||
| 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_6501 | |||||
| 資源タイプ | journal article | |||||
| 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 |
Yamada, Masatoshi
× Yamada, Masatoshi× Zheng, Jian× Zheng, Jian |
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| 抄録 | ||||||
| 内容記述タイプ | Abstract | |||||
| 内容記述 | Nuclear weapons tests were conducted at the Bikini and Enewetak Atolls in the Pacific Proving Grounds (PPG) in the Marshall Islands between 1946 and 1958. The 240Pu/239Pu atom ratios in seawater samples from the northern North Pacific Ocean and Bering Sea were determined to elucidate the temporal variability in 239+240Pu inventory, to identify their Pu sources and to propose the transport pathways of PPG-derived Pu into the studied area. Water column 239+240Pu inventory in the Bering Sea was lower than that reported for a comparable station in the Geochemical Ocean Sections Study, indicating that the Bering Sea inventory has been decreasing from 76.0 ± 3.0 Bq m-2 to 37.1 ± 0.9 Bq m-2 during the period from 1973 to 1988 at the average rate of 2.6 ± 0.2 Bq m-2 yr-1. The 240Pu/239Pu atom ratios in the water column ranged from 0.222 to 0.255 with a mean value of 0.235 ± 0.008 in the northern North Pacific Ocean and from 0.215 to 0.237 with a mean value of 0.224 ± 0.004 in the Bering Sea. The obtained 240Pu/239Pu atom ratios were clearly higher than the mean global stratospheric fallout ratio of 0.18. These high atom ratios proved the existence of close-in tropospheric fallout Pu from nuclear weapons testing at the PPG. The relative contribution of the global stratospheric fallout and the PPG close-in fallout were evaluated by using the two-end-member mixing model. The 239+240Pu inventories originating from the PPG close-in fallout were calculated as 17.9 – 25.4 Bq m-2 in the northern North Pacific Ocean and 11.6 – 16.6 Bq m-2 in the Bering Sea, which corresponded to 38 – 54% and 31 – 45% of the total- 239+240Pu inventory in the water column in the northern North Pacific Ocean and Bering Sea, respectively. A significant amount of the PPG close-in fallout Pu has been transported to the northern North Pacific Ocean and Bering Sea. The proposed transport pathway accounting for the high 240Pu/239Pu atom ratio in the Bering Sea water column is the transportation of PPG-derived Pu by the North Equatorial Current followed by the Kuroshio Current, Kuroshio Extension, North Pacific Current and subsequently the Alaska Current, and then the Alaskan Stream. |
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| 書誌情報 |
Science of the Total Environment 巻 718, 発行日 2020-02 |
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| 出版者 | ||||||
| 出版者 | Elsevier | |||||
| ISSN | ||||||
| 収録物識別子タイプ | ISSN | |||||
| 収録物識別子 | 0048-9697 | |||||
| DOI | ||||||
| 識別子タイプ | DOI | |||||
| 関連識別子 | 10.1016/j.scitotenv.2020.137362 | |||||
| 関連サイト | ||||||
| 識別子タイプ | URI | |||||
| 関連識別子 | https://www.sciencedirect.com/science/article/pii/S004896972030872X | |||||
