@article{oai:repo.qst.go.jp:00045056,
 author = {Yamada, Masatoshi and Zheng, Jian and 山田 正俊 and 鄭 建},
 issue = {1},
 journal = {Applied Radiation and Isotopes},
 month = {Nov},
 note = {Surface seawater samples were collected from a site in the vicinity of the nuclear fuel reprocessing facility at Rokkasho, Japan and sites along the Japan Sea coast.  239+240Pu activities and 240Pu/239Pu atom ratios were determined by alpha-spectrometry and isotope-dilution sector-field ICP-MS.  The 240Pu/239Pu atom ratio with the mean value of 0.227 +- 0.006 was significantly higher than the mean global fallout ratio of 0.18.  The contribution of the Pacific Proving Grounds close-in fallout was estimated to be 33 % of the 239+240Pu.},
 pages = {103--107},
 title = {Determination of 240Pu/239Pu atom ratio in coastal surface seawaters from the western North Pacific Ocean and Japan Sea.},
 volume = {66},
 year = {2007}
}