@article{oai:repo.qst.go.jp:00046781,
 author = {呉, 俊文 and 鄭, 建 and 田上, 恵子 and 内田, 滋夫 and et.al and 呉 俊文 and 鄭 建 and 田上 恵子 and 内田 滋夫},
 issue = {6},
 journal = {Environmental Science & Technology},
 month = {Mar},
 note = {The 239+240Pu activities and 240Pu/239Pu atom ratios in sediments of the northern South China Sea and its adjacent Pearl River Estuary were determined to examine the spatial and temporal variations of Pu inputs. We clarified that Pu in the study area is sourced from a combination of global fallout and close-in fallout from the Pacific Proving Grounds in the Marshall Islands where above-ground nuclear weapons testing was carried out during the period of 1952-1958. The latter source dominated the Pu input in the 1950s, as evidenced by elevated 240Pu/239Pu atom ratios (>0.30) in a dated sediment core. Even after the 1950s, the Pacific Proving Grounds was still a dominant Pu source due to continuous transport of remobilized Pu from the Marshall Islands, about 4500 km away, along the North Equatorial Current followed by the transport of the Kuroshio current and its extension into the South China Sea through the Luzon Strait. Using a simple two end-member mixing model, we have quantified the contributions of Pu from the Pacific Proving Grounds and the Pearl River Estuary to the northern South China Sea shelf are 68%±1% and 30%±5%, respectively. This study also confirmed that there were no clear signals of Pu from the Fukushima Daiichi Nuclear Power Plant accident impacting the South China Sea.},
 pages = {3136--3144},
 title = {Isotopic composition and distribution of plutonium in northern South China Sea sediments revealed continuous release and transport of Pu from the Marshall Islands},
 volume = {48},
 year = {2014}
}