pnereres waned eeee ee ee cee -8- AECD-3446 Section 1 ABSTRACT Speci.uens of fish, marine invertebrates, algae, plankton, land plants, land vertebrates, and water samples were collected for radio assay and identification from Bikini, Eniwetok, and the control area of Likiep. Areas adjacent to collection stations were monitored. Some of the proce- dures differed from those of earlier years in that frozen samples were processed in the Applied Fisheries Laboratory, ashing and plating methods were slightly changed and more carefully regulated, and samples were counted in an internal gas-flow chamber. The unit of measurement used for reporting activity was changed to disintegrations per minute per gram of wet tissue. Sample counts were corrected for geometry and backscatter, but not for self-absorption, which was kept to a minimum by preparing thin plates, The net count of a sample was calculated by deducting the backg round count plus three standard deviations from the gross count. Chemical sepa- ration of radioactive isotopes was not done but decay and absorption curves indicate the presence of Ce 144 and pyl44 Samples of 369 fish were analyzed for radioactivity relative to area collected, species, tissues, and feeding habits. The greatest amount of activity in d/m/g was noted in fish found in areas close to shot centers such as the deep water of the Target Area at Bikini (345) and in the shallow waters around the islands “f Aomon (703), Runit (144), and Engebi (125) at Eniwetok, The greatest concentrations of radioactivity were found in the viscera (1364) and liver (437) with less in bone (180), skin (10), and muscie (8) of most fish. The herbivorous species, such as parrot fish (572), contained much more radioactivity per gram than carnivorous feeders including plankton-feeders, The former averaged 382 in target areas while the two latter groups averaged 32. Small amounts of naturally-occurring radioactive isotopes were noted in fish from Likiep and other control areas, the d/m/g ranging from 0 to 7. 5. Radioactivity of invertebrates averaged from practically zero to as high as 1,100 at Bikini Target Area and 1,500 near Aomon-Biijiri. The most radioactive species included asteroid starfish, 5,100; hydroids, 2, 100; oysters, 820; and sponges, 580. Soft parts of shellfish were usually, but TWERSIEY ASES ES nwOF WAvil. fyLMUES . seep Py -Usds eat ad wa . area! tek Lie UNITY. Ul AE