239+240Pu and 137Cs concentrations for zooplankton and nekton in the Northwest Pacific and Antarctic Oceans (1993-1996)

The concentrations of Pu239+240 and Cs-137 in zooplankton and nekton in the Northwest Pacific and Southern Oceans were measured during the period 1993-1996. The object of the sampling was to assess the potential impacts of existing submerged anthropogenic-radioactive materials in the western North Pacific as well as the East China Sea. Samples from the Bransfield Strait of the Antarctic Ocean provided a control source impacted by only atmospheric bomb fallout. No particularly elevated levels of Pu239+240 were found in zooplankton samples from the Northwest Pacific, although significantly lower levels of Pu239+240 were found in three mixed zooplankton samples from the Bransfield Strait. The body burden of Pu239+240 in zooplankton appears to reflect concentrations in ambient seawater with some variation. Some additional Measurements Of Cs-137 in fish are also reported here to complement existing databases and for future reference in the regional marine en,. iron men tal radioactivity monitoring effort. (C) 2002 Elsevier Science Ltd. All rights reserved.