CHAPTERI
Gross
Activity
A.Land Plants
Thehighinitial 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
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.*
combination of these factors. Initially the activity in the coconut milk and meat was less
than other edible plants, but the rate of decline
of activity has been less than for other edible
Jand plants due principally to the higher percentage uptake of this longer-lived Cs".
Tables 1 and 2 show the analyses made by
NRDLfortheir first survey in February 19552
Table 3 is based on the February 1956 survey.‘
Tables 4, 5 and 6 show the analyses by
- HASLS*
Table 1—Summary of Gross Beta A ctivity in Miscellaneous Plant Samples*
AVERAGE ACTIVITY (uc/g x 10*) # >
IsLanD
Puant MATeRut
Likiep
Utirik
a
400
1000
47
LS
Basch
3000
53
2B
72
420
Labaredj} Kabelle
2800
5300
750
-------
1900
1800
Ww
B
10
740
120
Lukuen
2100
870
M40
Gejen
68,000
5600
160
no
100
Bt
20
20
Ll
46
Lomuilal} Bikar |Eniwetak
180
400
&4
200
a7
B
eo
a
35
© Wet wolght.
DAS
on basis TsO;
and
snd
*Collectlons made about February 1, 1055. Dats reported as of March1, 1955.
490
ao