Results of radiochemical separations by ion exchange columns and precipitation techniques on five plankton samples in and near the Pacific Proving Ground. * (7,8,9) 75,900 d/m/g ash Ryl06-Rp106 127,000 of total activity 3 44.9 not determined 9 0 3 9 Per cent activity O 12.5 13.7 13.2 8.0 3.1 0.4 0 9.3 0.3 0.3 9 0 5.7 not determined 0 Mn54 0.1 Fe? Feo9 19.4 0 19.2 0 12.7 0 27.6 O 38.8 O Cod? 9.9 8.5 15.5 6.1 46 C058 C960 zn©5 15.0 0.9 18.0 13.8 0.8 13.8 25.9 1.3 17.3 10.8 0.8 32.3 5.7 1.0 43.9 3 zy, trace 0 48,000 of total activity of total (57,58,59) d/m/g ash activity of total Plankton d/m/g ash activity. 0 C3137 (Bal37m) 198,000 a/m/g ash Vv (50,51,52,53) Per cent 4.7 gr89-90** (43,44,45,46) Per cent 24.9 Celt4_ppl 44 28,799 d/m/g ash IV Plankton Per cent 7.1 Zr9-NbID (13,14,15) III Plankton Per cent of total ‘Isotope II Plankton Q * The data a corrected to date of collection ** Chemical s dfarations for sr89-90 were madg on duplicate aliquots in addition to 9/ the resin célumn separations. Neither Sr89 nor Sr9 was detected. ’ I Plankton -TtTt- Table 1.