40 of the transuranic inventory in the water column of the lagoon. 237 The Np concentrations in the lagoon and crater water samples were less +. to 1.42 and averaged in 56 soil samples from 7 islands ranged from 0.066 water and biota 0,84 + 0.37 (Ga75), while the average ratio in 7 marine Neither average value determined in the than 0.2% of the measured 239 2405, concentrations in those samples. samples was 0,66 + 0.40. Plutonium 0.65 + 0.05 environmental samples differed preatly from the average of Many types of samples from the Atoll contain 2385 239, 240, Pu, and 244 Pu. Most reported values are the sum activities determined by alpha spectrometry. o ¢ 239 Pu and 240p,, distributed widely throughout the Atol] and were detected in nearly Atoll ed tissues of organisms in the Atol] if feeding and living are restrict to specific regions of the Atoll. The average 24051 .239py ratio in the yearly wrowth sections water samples, sedimentary components (including fine unidentifiable live sample of Favites virens coral carbonate sands, coral fragments, Halimeda debris, foraminifera, and Bikini Lagoon was 0.77 + 0.07 mollusk shells), isotopic ratio in Enewetak samples. living algae, benthic invertebrate tissues, planktonic species, and marine vertebrate tissue all contain 23942405.) The distribution of 2385, is ag wide among components in the marine environment as is 23942405 u, but at lower concentrations. 238, The similar isotople ratio in isotopes by mackeral tissue shows no obvious discrimination in uptake of These radionuclides are every type of marine and terrestrial sample analyzed to date. for global fallout debris (Kr 76). The 23H 240 Pu ratio determined in a variety of aquatic samples from ws collected from the western basin in (No 75). This value is similar to the However, the mean isotopic and Eneu Islands is concentration ratio in soil and vegetation of Bikini 1.15 (Mo76), somewhat higher than the average in the Bikini coral sample. samples Since the 2405, 239py activity ratio in sowe environmental , ; different regions of the lagoon ranges from less than 0.04 to greater exceeds 1, it seems inappropriate to use the shorthand notation, than 0.50, when referring to the sum of A few activity ratios of 2405, 239Pu was determined by mass spectrometry, The ratios in two water samples collected from the lagoon during 1972 were 0.432 and 0.289 (No74). Samples of mackeral bone and viscera collected in 1972 near the island of Glenn had 2405,,239p, activity ratios of 1.15 + 0.25 and 1,27 + 0.26, respectively, while been done in the literature, 239 Pu and 240 239 Pu, Pu activities as has so often Throughout this report, 2394240 iL Pu wi as 239 Pu while refer to the sum of the activities of the two radionuclides, will refer to only that isotope. 197? In two Enewetuk lagoon water samples collected during 2415, was measured by mass spectrometry. (No 74), ceauity 2394240 Pu activit 24h Pu:’* y The In the 197? growth goatfish viscera and tridacna tissue from nearby David had ratios of ratios as of December 1972 were 1.24 and 2.56, 0.68 + 0.07 and 0.66 + 0,19 (Ga 75), respectively, section of the previously mentioned live coral frav Hilini, The activity ratios cf a the pon ARCBEE