Contamination from Local Fallout lagoon bottom silt and lagoon water was similar to that of the soil at 1 year (Rinehart et al, 1955). At 2 years the gross activitv in water samples was of a verv lowlevel. The observable activity was (as determined at 1] year} due primarily to the rare earth elements (table 4}. Fish and Marine Specimens The level of radioactivity found in the tissues of fish and manne invertebrates collected at 2 vears, while only 3 per cent of that found in fish collected at ] month (3 wc/ke} was nevertheless readily detectable (Weiss et al, 1956). Considerable variation existed in the concentration of activity per weight as a function of the geographic location of the fish and marine specimens. In the Rongclap Atoll, for example. fish and invertebrates caught in the northern part of the Jagoon at ] vear contained, on the average. 3 to 4 times the amount of internally deposited fission products as was found in similar specimens from the southern part of the lagoon. This finding is consistent with the fact that the northem lagoon way exposed to higher concentrations of fallout maternal. ‘Average external gamma readings of the northern and southern Roungelap Islands at the time of sample collection were 5.8 and 0.7 mr/hr, respectively.) This difference im concentration of radioactivity im fish from the north and south lagoons way not noted at 2 vears. Apparenth the activity was completels diffused throughout the lagoon by this time. While there was considerable vanation in the concentration of actinity of individual fish from some aicas. no cor:clation could be found between the levels of radioactivity and the cating habits of the fish (carnivorous, herbivorous, and omnivorous). Snails concentrated radionuclides to a much greater extent per unit body weight than did the fish in the corresponding localities. This concentrating ability may be due to the fact that snails feed on the lagoon bottom where higher concentrations of nuclides are found. Crabs and clams also showed high fission product concentration at ] vear (Rinehart et al, 1955). Approximately 40 per cent of the activity of fish collected at one vear in the Rongelap and Rongerik Jagoons was fixed in the skeleton. Muscle and viscera contained approximately 15 and 20 per cent, respectivelv, of the total internal activity. The remainder of the activity was found on the skin and the gills. At 2 years the skeleton contained 50 per cent of the beta activity, the viscera 33 per cent, and the muscle 14 per cent. The distribution was verv similar to that found after 1 vear, Zn, a “neutron-induced”activity, accounts for the high gamma-to-beta ratio observed at | and 2 years. Zinc wasfairly evenlydistributed throughout the tissues, contributing about 90 per cent of the activity in the skeleton and muscle (Weiss et al, 1956). The level of Sr®° was uniformly low in the marine speci- mens. 51constituted less than J per cent of the total, and was found chicfly in the skeleton. The muscle of fish caught in the Rongelap lagoon in 1953 had average values of 200-300 pyc Sr9°/g of calcium (Weiss ct al. 1956). oo ce fhe Loan CsI 315