CHAPTERIi
Gross Activity
A. Land Plants
Thehighinitial activity of the “edible plants’’
(Graph 2) was probably due to surface contami-
nation 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 ac-
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
NRDLfor their first survey in February 1955.?
Table 3 is based on the February 1956 survey.‘
tivity 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"’.
Tables 4, 5 and 6 show the analyses by
ee
HASL-:&
Table i—Summary of Gross Beta Activity in Miscellaneous Plant Samples*
AVERAGE ACTIVITY (gc/g x 105 5 >
Punt MaTeRu.
IsLanD
Likiep
Utirfk
Grass. ..--.----..-------..5.
xn
Coconut leaf... .-..---..----}--....--
400
W000
Rongelap| Busch
3000
i
[eee fe
Coconnt frond stem.......-.-}-..---..]--2 22.222 e fee
Coconut shell.
Coconut husk......-..---..o
Coconat sprout.
LT?
L6
Bprouted coconut roots... -..)-....-2 fe.
Besevols leaf.
Scaevols trunk section ......}-.....-Arrowroot stam.
Arrowroot leaf... .-
-
8300
78
eee] eee eee ee
53
W f.---.22.]--2- 2-22
72
fee
|- - -.]- - - -] -. eee eee
Kabelle
Lukuen
1900
1900
fee en eee
20
2.0
L1 j.
Bananas
46
[o f
140 |-.........]....-----.]--------]------ ene
150
7
Ho
H10 |..2..2--..
740
ee eee een]
35
fee
fe ek
= Wot weight.
© As determined on basis U:O: standards and empirical) scattering and absorption corrections.
*Collections made about February 1, 1955. Data reported as of March 1, 1055.
Lomuilal) Bikar {Eniwetak
2100
8, 000
5600
180
mo
670 fie] fee eee
120 }..-----...
apennneee ene feee nnn eee
61 |..-----. ween
eee] ee eee
Gejen
M7 |..---.....
19 j.---2 22 |---| eee ee ee fee
Pumpkin.
Limes_.-.....--Taro
Vines...
Eniaetok| Labaredj|
100
fe
200
&4@ fol
fe eee
67
2
oO
eee] eee [ene een ee
ee
fee eee ee
fee fe
[ae eee |e eee nee
om
mo
5