7) Station B-30. Compared to the nearly logarithmic decrease in .oncentratitons between these stations, the concentrations of at a rate of 3.5 times faster than the Pu 137 Cs decrease 23942405. concentrations measured. 239+240 distribution of similarly increasing 239+240 The Pu/ 137 ~'Cs ratios to the northwest of the Zuni Crater ranqe from 5.76 to around 30-40 and indicate the second distribution observed. These data show that relative to the distributions of 23942405, 24h am, and 155 Eu, the regions of high 1376 concentrations are restricted in geo- graphical area. Such localized regions of high 137 Cs concentrations were also noted by Nelson and Noshkin (1972) in the surface sediments of Eniwetok Atoll lagoon. Because 13766 has volatile radioactive precursors, its initial distribution might be expected to be significantly different from the refractory radionuclides Pu, Am and Eu. 5.1-6 Bismuth-207 and Cobalt-60 The areal distribution of the concentrations observed for the induced radionuclides between that for tribution of 238 2074 and 606, (Figs. 16 and 17) is intermediate Pu and that for 2394240, u. The similarity of the dis- 207 Bi and 60 “Cot 0 239+240 Pu is that decreasing concentrations in lagoon sediments appear to radiate from high concentrations at Stations B-2 or B-20; the ratios 239+240 pu/"'Co across the central lagoon. 207 Bi to that found for 238 and 23942405 1/278; are almost constant The similarity of the distribution of 60 ~Co and Pu is that the highest measured concentrations of these three radionuclides occur in crater sediments and show Jarge and systematic variations at different locations in Bravo Crater. Bismuth-~207 is an induced radionuclide produced by reactions such as 2065), (d,n) 20755 Struction material. The lead was present probably as a device or harge conSince the major source of 2078, to the lagoon environment