67 kev (FWHM). Fach sample was counted for 48 - 72 hours to collect reasonable counts for acceptable statistics. PrSULTS: Table 1 gives the data on R series of sea water samples which were collected inside of Rikini Atoll. Table 2 is for the C series of samples collected in the crater areas of Rikini Atoll and Table 3 is for the f series samples in the open ocean surrounding Rikini Atoll. The samnle loca- tions and concentrations of plutonium are plotted in Fig. 1, aman of Rikini Atoll. Following are some of the salient points of the prrliminary report: (1) ® series sarmles exhibited concentrations of Pu2°9*240 From 35 dpm/IM00L to 283 drm/T000L. tions were found Higher concentra- in the northwest and lower in the southeast. (2) The concentration of plutonium in bottom waters was generally higher than the surface concentration at the same location; the onlv exceptions were sample R-7, which was collected at the mouth of Pukoii Pass, and sample R-26 from the east-central area of the Lagoon. The presence of excess plutonium in most samples from depth is consistent with the premise that the primary source of Pu is from contaminated crater sediments and the physical and hiological sedimentation and the 59905524 oO h