7

radionuclides are in the top 15 cm of the soil; however, in some disturbed

areas of Bikini Island (i.e., Profiles #1 and N) significant quantities of
some radionuclides, especially ? St are found as much as one meter below
the surface. The decline of Os (figure 6) concentration with depth is

shown for a profile in disturbed (N) and relatively undisturbed (#9) areas

on Bikini Island,
In an undisturbed profile Pu, Am, and Eu values decrease
the fastest and $0
Osr values decrease least rapidly with depth.
The mean concentrations of 137 ¢6 90¢ and 241 an and 239,240, in the

top 10 cm of soil from the soil profiles on Bikini Island are given in Table
3. Values in this table are the means of the’ incremental samples - 0 to 2.5,
2.5 to 5, and 5 to 10 cm - from a profile with the 5 to 10 cm value weighted

twice as heavy as the other values. Radionuclide levels are highest in the
south-central part of the island (profiles 3, 10 and L) and in the area of
the main garden (profile 12).

Strontium-90 was the most abundant ac epee

fgllowed jp
in gorder of decreasing abundance by 137cs, 239,240py, 24lam,
Co and

1¢5sp,

Limited soil collections made on Enidrik Island show a slightly different
pattern of radionuclide abundance (Appendix Table 33). Plutonium-239,240 was

more abundant than 90Sr at 2 of 4 sites, and 102mRh was more abundant at one
site.

Radionuclides in soils from Nam werg present in greater quantities (i.e.
90sr, 1,160 pCi/g; 239,240Pu, 637pCi/g; “41am, 470pCi/a, dry) than on Bikini

Island, but the relative abundance of the radionuclides in soil from Nam was
the same as in the soil from Bikini.
IJIron-55 values in soil from Nam are also

higher than in Bikini soil.

A sample of noddy and sooty terns was also collected on Nam.

ofgf Sb birds contained the following radionuclides:
Sr, 0.04; and 40k, 8.5 abe dry weight.

contained 137¢s (0.1 pCi/g),
(0.07 pCi/g).

7es,

Ths muscle

<0.1;

6¢0

The eggs oF these birss

4.2 pCi/g), ©0Co (0.06 pCi/g) and

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