Levels in the sea of naturally occurring nuclides of elements also present as radioisotopes in fallout. Also shown are the physical forms of the naturally occurring elements in sea water, per cent solution of fallout radioisotopes in sea water, and percentages of radioisotopes observed in plankton. Gram/ton of Form of in sea water element in stable element (ppm) (8) Fallout in sea water stable Per cent in solution sea water evidence (8) Indirect Direct evidence (9) Isotope zn©5 O14 mostly 02 ~~ Co27, 58,60 .0001 solution*# 0007 -- Feo? Zr9o-Nb?> 02 ? Celth_pplth 0004 Mn54 solution*** particulate** 2 .00007 -- 2 .001 01 mostly .002 C337 002 mostly --* gr89.99 13 mostly Rut06_R106 Stable calcium " potassium 2 ? -- solution** solution solution HOO. solution 380. solution -1.0 7.2 * A value of .05 per cent is given for cesium. percentage fallout elements in element in five form of sea water particulate " of radio- plankton samples 25.1 24d " " 23.5 20.2 " 1.4 0 " -- " 0 Average Principal 70 solution 87 solution 8.6 0.2 0.2 The apparent insolubility is caused by a strong adsorption of the cesium fon to colloidal particles of hydrolysate sediments and not to its insolubility in sea water. **# Goldberg 1954 (7). *#* Kawabata, personal communication. -9T- Table 3.

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