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Gross Activity
A. Land Plants
The highinitial activity of the ‘edible plants”
(Graph 2) was probably due to surface contamination caused by the direct fallout. The rise
in activity after a year after the fallout occurred
may be due to (a) sampling and counting variances, (b) the ability of some plants to concentrate Cs’ (see Section Radiochemical Analysis), (c) the increased availability of the
radioactive fallout material to the plants, or (d) a
combination of these factors. Initially the activity in the coconut milk and meat wasless
than otheredible plants, but the rate of decline
of activity has been less than for other edible
land plants due principally to the higher percentage uptake of this longer-lived Cs'*’.
Graphs 2 and 3 indicate the general levels of
activity of edible plants (pandanus, papaya,
breadfruit, arrowroot), and coconut meat and
milk at Rongelap Atoll together with their
decline of activity with time.’?
Tables 1 and 2 show the analyses made by
NRDLfortheir first survey in February 1955."
Table 3 is based on the February 1956 survey.‘
Tables 4, 5 and 6 show the analyses by
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Table 1—Summary of Gross Beta Activity in Miscellaneous Plant Samples*
AVERAGE ACTIVITY (uc/g x 108) 6 5
PLaNn? MateeaL
ISLAND
Likiep
Utirik
Rongelap| Busch
Gragg. ...-- 2222-22222 22 eee
xn
400
8000
Coconutleaf....---....-----[------2.
WOO
fone. een
Coconutfrond stem.........[--.--..-}----2-----[---- eee
Cooonutshell..........-.---|-..--.-2}---------- [ee eee
Coconuthusk...............
L7
Ls
53
Coconut sprout. .-_.-------.|--22----|---- weet}
8prouted coconut mots
Enlaetok| Labaredj
Kabelle
42
fee eee ee fee
[eee eee] ee
fe eee]
{..--- 22 .[-----efew e eee ede ee
* Wet weight.
» As determined on basis Us0, standards and empirical scattering and absorption corrections.
*Collections made about February 1, 1955. Data reported as of March 1, 1955.
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Gejen
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