title: Determination of 240Pu/239Pu atom ratio in coastal surface seawaters from the western North Pacific Ocean and Japan Sea.
abstract: 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+240)Pu activities and (240)Pu/(239)Pu atom ratios were determined by alpha-spectrometry and isotope-dilution sector-field ICP-MS. The (240)Pu/(239)Pu 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+240)Pu.
authors.affiliation: Nakaminato Laboratory for Marine Radioecology, Environmental Radiation Effects Research Group, National Institute of Radiological Sciences, Isozaki 3609, Hitachinaka, Ibaraki 311-1202, Japan. m_yamada@nirs.go.jp
authors.forename: Masatoshi
authors.initials: M
authors.lastname: Yamada
authors.forename: Jian
authors.initials: J
authors.lastname: Zheng
mesh_terms: D007564:Japan; D054043:Nuclear Weapons; D010140:Pacific Ocean; D011005:Plutonium / Q000032:analysis* / Q000737:chemistry; D011847:Radioactive Fallout / Q000032:analysis; D011854:Radiochemistry; D012623:Seawater / Q000737:chemistry*; D014875:Water Pollutants, Radioactive / Q000032:analysis*
chemical_list: D011847:Radioactive Fallout; D014875:Water Pollutants, Radioactive; D011005:Plutonium