Zl “a 5 the separated foraminifera and coral fragments from station 40C are, growth increment from this coral since 1954 was the 2394240), however, at least 2.5 times higher than those associated with their concentration below 104 + 12 pci/kg. respective components at station 3D, The distribution of 2394240 Pu is Lower concentrations are associated with coral remains deeper in the sediment column, From the different among components in the sediment from different regions of the radiological record retained in the skeletal matrix of the Favites lagoon. virens, coral labelled during 1954 and 1958, for example, should have The fine fraction at these locations contained the highest concentration of 2394240, To within our analytical precision, the 2394240 Pu concentrations of 39x10 3 and 4.5 x 10° pci/ke, respectively i 238, 239240, concentration ratio is identical in the components from (No75). both stations, in any subsurface coral remains. In the sediment column from Bikini station 3, associated with all components that were separated, 2394240, is At all depths in These concentrations are orders of magnitude larger than those This data, thereforc, does not support translecation of labelled coral material deeper into the sediment column by physical processes during or after testing. Burrowing, organisms the sediment column, the highest concentration of 23942400, in the could redistribute some fraction of labelled sedimentary components tc coarse components was associated with Halimeda fragments. depths in the sediment column, Sedimentation of labelled material to the lagoon occurs at a rate that is too slow to account for the buried activities below a few mm in the sediment column. Although the age of the Halimeda fragments, coral, and other components at depths greater than a few cm must therefore predate the test years, 2394240), , is associated with these components. The possibility that subsurface remains labelled during testing However, when the 2394246, activites associated with each component at various depths are conpatred to the activity in the corresponding component at the surface, the activities differ. 23024 o Spy For exampic, between 5 to 10 em the PB H24G, | concentrations associated with the coral, Halimeda, foraminifera, and shells are 1.29, 0.83, 0.43, and 0.34 times the concentrations associated with those components in the surface layer. Burrowing and were buried later in the sediment column by large scale turbulence can mixing processes by organisms are not likely to move specific component be discounted. selectively down through the sediment column. Coral or Halimeda fragments directly subject to a nuclear explosion probably would not retain their identity. In recent The data indicate that al] plutonium does not remain associated yearly growth increments of a living sample of Favites virens coral from with the sedimentary materai] with which it was originally deposited. station B3, the 23942405, concentrations averaged 104 + 12 pCi/kg Small quantities of plutonium are remobilized continuously from the (No75)}. sediments to the layoon water column by surface exchanve rechanisms. This value agrees well with the 2397240, concentrations in dead coral] remains in surface layers at station B 3. In no yearly Plutonium is also detected in the interstitial water extracted in situ aor pncervee