Table ILI. Radioisotopes Present in Plankton Collected soon after Fallout Isotope Half life Per cent of total radioactivity Bomb debris Np239 2.3 days 69 u237 6.8 days 3 Fission products Mo99-T.99m 66 hours 12 Te 132-7132 77 hours 8 Ru103-Rp103 40 days Rut95_Rp,105 36 hours?) Ruy 106. Rp 106 3 1 year Bal40-7,a140 12.8 days 2 Cel4l_p, 141 33 days 2 Zr95-Nb95 65 days 1 285 days £1 Cel44_p,144 100+ 1) Data from Lowman (1960); average value for six samples collected less than 48 hours post shot; fallout from one detonation; Rehoboth survey (1958) 2) Half life of daughter

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