A gamma energy spectrum analysis of Core No. 4 showed the presence of 530 yyuc of Ce, 470 uuc of Ru!, and about 10 yc Ra™* per gram of dry sediment. These values were the average through a 3-mm segmentof the upper surface of the sediment. If the activity were confined within a thickness of a few microns of the upper surface, the specific radioactivity would be much higher. 1.6.6 Lagoon Sediments. A number of samples from the surface of the Bikini Lagoon floor were assayed with the results shown in Figure 1.7. The total gamma photons (0.08 to 1.5 Mev) emitted per minute per gram of dry sediment ranged from 250 to 8,300 (y/min)/gm, with the greatest radioactivity in the west and northwestern section of the lagoon. In general, with the exception of living calcareous algae, the activity was inversely proportional to the size of the sand grains in a given weight of sample. No separation was made of the bottom organisms such as foraminifera from the inorganic sand. However, samples containing a large visible proportion of living foraminifera showed a somewhat higher activity than those samples containing no visible living organisms. TABLE 1.12 GAMMA ACTIVITY OF MARINE LIFE IN BIKINI LAGOON, (7/min)/gm WET WEIGHT, 1 MAY 1956 ™ . Perch, unidentified Sea Bass, Plectropomus Lutjanus bohar Snappers, Aprion virescens Snapper, unidentified Mullet, Neomyxus Goat Fish, Upeneus Tuna, Neothunnus macroptarus Clam, Tridacna mantle Epidermis Caudal fin Gill fllamente Liver Muscle Spleen Stomach veriebral and nts columa 1,080 4,000 1,260 780 860 860 6,600 2,960 1,540 1,700 450 1,530 2,400 1,800 1,440 1,280 48,000 36,000 20,000 18,000 160 1,030 380 200 320 2,600 _ _— _ —_ _ 1,900 1,560 600 $60 _ 1,300 2,100 1,250 1,470 1,806 1,560 11,400 2,800 2,200 25,000 ~ 1,100 8,700 31,000 22,000 11,630 620 410 1,170 _ _ 6,940 900 430 _ 2,400 1,900 10,700 330 36,500 _ _— 640 _ 175 — A typical gamma energy spectrum of unprocessed lagoon sediment is shown in Fig- ure 1.1. Ru! and Ceare clearly evident. The analysis of several other bottom samplesis listed in Table 1.13 showing the presence of Ceand Ru'™ in all samples other than a tridacna shel] and traces of Zn", Co®, Mn, and Zr’® in several instances. Bottom organisms such as the sea cucumber, sea urchin and finger snail, as well isotopes. Samples of beach sand and soil above the high water mark from Sifo Island at Ailinginae, Site Nan, Bikini, assayed from 50 to 350 (y/min)/gm of Ceand Ru’. . as the corals and calcareous algae, exhibited Ce! and Ru! as the predominant radio- 1.6.7 Miscellaneous Survey of Land Organisms. Several spot checks were made on the plant life from Enyu Island (Site Nan) in Bikini Atoll and from Sifo Island at Ailing- inae. The meat of three green coconuts from Enyu averaged 107 (y/min)/gm while the 30 (tilts ctnntiectitives tarts enie- ‘ hibited 940 (7/min)/gm while a sample from below the low water mark showed 1,210 (y/min)/gm of Ceand Ru, bedi A sample of beach sand from above the high water mark on Site Charlie, Bikini, ex-