samples through the root zones of the sampled trees. From these data, we The concentration factors determined from this survey are more pre- developed concentration factors (CF) cise and provide a better basis for relating concentration in food prod-~ estimating the average radionuclide ucts to. soil concentration, concentration that would be expected as well as concentration ratios that relate the from crops planted in certain regions concentration in the vegetation (leaf) within an island or on different to the concentration in the edible islands, fruit, or the concentration in indi- Despite the greater precision of cator species (Seaevola and Messer- concentration factors calculated from schmidta) to concentrations in food associated vegetation and soil data; crops. these values still show some variabil- A separate report? discusses in ity. detail the results of the sampling be accounted for by several factors program and the calculation of CF and acting either alone or in concert. concentation ratio, These factors include differences in: In brief, the distribution of radionuclides in both e the Bikini and Enewetak environment was nonhomogenous. Radionuclide con- e Tatas suet eee Physiochemical properties of the radionuclides; over distances of only a few feet. e Soil management practices; The results of our work during this e Irrigation practices; and survey verified our thesis that @® Physiology, age, and prior his- because of the wide variability in soil concentration with location, tory of the sampled plants. use- One would, in fact, expect to see some ful concentration factors can only be variation in sampling conducted from a calculated from vegetation and soil specific tree merely resulting From data sampled from the exact site. normal biological variability. Concentration factors derived from Sale Soil type, organic content, and chemical characteristics; centrations in soil varied greatly In addition to the calculation of. soil sampled from the root zone of the CF, the data From the large surface- vegetation under investigation showed soil sampling program” were used to a greatly reduced range of values com- determine average soil concentrations pared with values developed earlier in four regions on Bikini Island and from vegetation and soil samples from in the whole vf-Eneu Island. different sites but in the same average soil concentrations were then are a used along with the concentration fac- 34,35 (see also Table 22, this These tors to predict the radionuclide report). j ' py oS Se ate cea te This remaining variability can 5009980 -30-