title: Spatial and temporal distribution of Pu in the Northwest Pacific Ocean using modern coral archives.
abstract: Historical (239)Pu activity concentrations and (240)Pu/(239)Pu atom ratios were determined in skeletons of dated modern corals collected from three locations (Chuuk Lagoon, Ishigaki Island and Iki Island) to identify spatial and temporal variations in Pu inputs to the Northwest Pacific Ocean. The main Pu source in the Northwest Pacific is fallout from atmospheric nuclear weapons testing which consists of global fallout and close-in fallout from the former US Pacific Proving Grounds (PPG) in the Marshall Islands. PPG close-in fallout dominated the Pu input in the 1950s, as was observed with higher (240)Pu/(239)Pu atom ratios (>0.30) at the Ishigaki site. Specific fallout Pu contamination from the Nagasaki atomic bomb and the Ivy Mike thermonuclear detonation at the PPG were identified at Ishigaki Island from the (240)Pu/(239)Pu atom ratios of 0.07 and 0.46, respectively. During the 1960s and 1970s, global fallout was the major Pu source to the Northwest Pacific with over 60% contribution to the total Pu. After the cessation of the atmospheric nuclear tests, the PPG again dominated the Pu input due to the continuous transport of remobilised Pu from the Marshall Islands along the North Equatorial Current and the subsequent Kuroshio Current. The Pu contributions from the PPG in recent coral bands (1984 onwards) varied over time with average estimated PPG contributions between 54% and 72% depending on location.
authors: School of Geography, Earth and Environmental Sciences, University of Plymouth, Drake Circus, Plymouth, PL4 8AA, UK; Marine Environment Research Department, Korea Ocean Research & Development Institute, 1270 Sadong, Ansan 426-744, South Korea. Electronic address: patriclindahl@yahoo.com.
authors: Patric
authors: P
authors: Lindahl
authors: School of Earth Sciences, Bristol Isotope Group, University of Bristol, Wills Memorial Building, Bristol, BS8 1RJ, UK.
authors: Morten B
authors: MB
authors: Andersen
authors: School of Geography, Earth and Environmental Sciences, University of Plymouth, Drake Circus, Plymouth, PL4 8AA, UK.
authors: Miranda
authors: M
authors: Keith-Roach
authors: School of Geography, Earth and Environmental Sciences, University of Plymouth, Drake Circus, Plymouth, PL4 8AA, UK.
authors: Paul
authors: P
authors: Worsfold
authors: Deep-Sea Resources Research Division, Korea Ocean Research & Development Institute, 1270 Sadong, Ansan 426-744, South Korea.
authors: Kiseong
authors: K
authors: Hyeong
authors: Division of Earth and Environmental Science, Korea Basic Science Institute, 113 Gwahangno, Yusung-gu, Daejon 305-333, South Korea.
authors: Min-Seok
authors: MS
authors: Choi
authors: Marine Geology and Geophysics Laboratory, Korea Ocean Research & Development Institute, 1270 Sadong, Ansan 426-744, South Korea.
authors: Sang-Hoon
authors: SH
authors: Lee
mesh_terms: D000818:Animals; D037421:Anthozoa / Q000737:chemistry*; D008849:Micronesia; D015205:Northwestern United States; D054043:Nuclear Weapons; D010140:Pacific Ocean; D011005:Plutonium / Q000032:analysis*; D011834:Radiation Monitoring; D011847:Radioactive Fallout; D014875:Water Pollutants, Radioactive / Q000032:analysis*; D014878:Water Pollution, Radioactive / Q000706:statistics & numerical data
chemical_list: D011847:Radioactive Fallout; D014875:Water Pollutants, Radioactive; D011005:Plutonium