18 6 Zn 5 peak. The presence of zn°> is corroborated by the 0.5-mev peak. 8 also shows the gamma-ray spectrum of noddy tern Fic. guano collected in this area. , over the 1.17 peak of Co 60 The 1.12-mev peak predominates and the 0.51 peak of Zn 65 , . is evident. Tne foliar contribution to the litter contains only cs*37 from among the gamma-emitters. . 137 90 . toa In undisturbed areas Cs and Sr are being deposited with the litter and are thus replacing at the surface some of the Cs 137 and Sr 90 . lost by leaching. : tos There is not sufficient data from the field work to determine whether there eventually will be a loss of these radionuclides from the soil-plant system, or a steady state (excluding physical decay of the radionuclides). Long-term experiments, under simulated field conditions, with monolith lysimeters and controlled and uniform addition of the radionuclides would define this point. Young Soil Fig. 9 gives the spectra of the 0 to l-inch, 1 to 2-inch, . and 9 to 10-inch increments of a young soil. 60 65 144 Co, 2n ~, Ce - prit4 and But? were detected only in the surface layers, and with increasing depth the 0.60 to 0.66-mev photopeak region of the spectra shifts toward the 0.60-mev peak of sb? , The spec- trum of the 9 to 10-inch increment is compared with that of an spt? spike in Fig. 10, showing that the photopeaks of the soil and spike gamma spectra are identical. AS