The same tendency of regional diffe- On the other hand, the In the North Equatorial The predominance of 95Zr-95Nb in plankton was re- Resear- concentrations of 1 ‘cs, content of fishes. On the other hand, no appreciate amount of 2°Zr - 95Nb was found in other organs of fishes. Ok in the plankton and the gill, intestine and stomach gpalysis, 95Zr ~ 99Nb, was easily detected with 652n and TSsues| were 1.07<9.54 uuc/Kg (0.05~0.43 s.u.) in 6~18.54 “esfKg (0.29~0.58 seu.) in the n skin. In the intestinal organs, 146 ~357auo/Kg 365 of °-2n and 60 ~147 uuofKg of 60co, were determined. According to the results obtained by gamma-ray pyls hight Concentrations of 90gy #a¢/Kg, and that of sr, were from 0.1 to 0.2 aacfKg of wet samnle. varied from 6.0 to 22.5 Tsh muscles} Radiological Seiences and Japan Analytical Chemistry ray Scintilation surveymeter, and detectable radioactivity were not observed, Radiochemical analysis on sample fishes were carried out in two institutes as National Institute of The radioactivity survey on fish surface was done with 7 - cognized with r-ray spectrometer by Tokai Regional Fisheries Research Laboratry. served, among the types of organisms and currents was hardly ob- This was approximately equal to the data obtained in Japanese waters. Differences in radiation contamination 1172 dpm/O.5g of ash. Gross f-radioactivity inplanktoy ranged from 114 to at aters/under survey were practically all of a low level. In general, it was recognized that the activity in the Current, higher concentrations of nuclides were found above the thermocline than below. for 137¢s and 1.5 ##¢/é for l44ce. mean values found in the North Equatorial Current and Equatorial Countercurrent were 0.2 nac/g for 99Sr, 0.4 nuc/g for’ 137s and 0.5 ##0/g of 144ce. in the Equatorial Current were 0.1 uuc/g for sr, O31 aady rence in the concentration of nuclides was also observed. According to the results obtained by Hydrographic Division, Maritime Sofety Board Agency, the mean registered 1-3 “4°/,, The comparative results of o11 types of physica and did not reveal any significant symptoms which could be regarded as products of radiation. “biochemical examinations of the crew before and after the cruis S0-m} dual Based on measurements made with film badges, indivi an tessth was cruise entire the radiation exposure doses during Helth Pbysic