CHAPTERIl
Gross Activity
The highinitial activity of the “edible plants”
(Graph 2) was probably due to surface contamination caused by the direct fallout. Therise
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!*7 (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 was less
than other edible 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’.
A. Land Plants
Graphs 2 and 3 indicate the general levels of
activity of edible plants (pandanus, papaya,
breadfruit, arrowroot), and coconut meat and
mik 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 19553
Table 3 is based on the February 1956 survey.‘
Tables 4, 5 and 6 show the analyses by
HASLS: 8
Table 1—Summary of Gross Beta Activity in Miscellaneous Plant Samples*
AVERAGE ACTIVITY (uc/g x 108) = >
PLANT MATERIAL
Grasg___._---.--.-.-------4-
JsLAND
Likiep
Utirik
20
400
Rongelap| Busch
3000
420
Enfaetok| Labaredj|
2800
5300
Kabelie
Lukuen
1900
2100
Gejen
68, 000
Lomuiial|
5600
Bikar
|Eniwetak
180
400
Coconut leaf__....-...------}---.---11000}
750
1800
670 [__._..----]--.---.---]..---_--|---------Coconut frond stem__.-...--|....-_.-]-.--.---.-] -.--.----}----- fee eee eae eee
140 [_.-.0.2-- [2 eed eee fee eee
Coconut shell.....---....---)_....2-_}--- ee) ee |e ef e eee p ee
17 |.--------[50 |... fee fee
Coconut husk......-....--..
17
1.5
63 |... }---- 2 fe.
73 \__------_110 }-_----.--8.4 |..--.----Coconut sprout.__....---.-.]....----]-.-..----28 |.------_|-------- |e e ee
110 [_------_--]---.-----_{--_.-- ef -. ee eee eee
Sprouted coconut roots. ....)....---.}---------72 |-.-.--- |e
eed. ee
740 |_.-------we e
e e] eee --f-ee ee fee- eee eee
Scaevola leaf_...__._....-----]-_-..---|-------..-| ..--------|--------|----- ee fee
120 }__-..-._-100
20)
6.7
60
Scaevola trunk section......].......-]------.---] -.---2---}--- ee fee} fede eee} eee ee
-e--f
23
[oles
ArTrowroot Stem__._...------}.----.--}_----.-__-19 ).-- eee} yee |e] eeu)... -- --------]---- +--+
Artrowroot leaf........-..-..}.----.--}---------61 |]... feet epee ee] ee eee -
Pumpkin, ....--...-..---.--
20 }_--..---.-
35 |.-----._|----------]----..----|----------}----------| eee eee ee ee =| ee eee
Limes. __.-..--..---.---.-BO Le) Lee yeep |e) ie]. ee ---|----.----]--------}------ eee
Taro.._-----..---.---------Lal fou. eu] -----_---|----- 2. |-- ee] |e | eww) eee ee |e -- J ee eee
Banana ....-----._---.-----4.6 |_-2- .f woe |---| ee. ee] |e ee] eee) eee feee] eee
Vines... _.-. 22-2. ew --| ee [nee ee] eee] } ee] eee
490 |e. ef
340
* Wat weight.
+ As determined on basis U30s standards and empirical scattering and absorption corrections.
*Collections made about February 1, 1955. Data reported as of March 1, 1955,
5