ae
tenes
ss
p
anGibiens
adhe teens She
Nhe meantliam TE
Te.
n 1 (A
residual surface contaminatton eccaunts fur the higher activity
of the external plant parts.
Levels of activity in successive collections through and
including December 1954 drop in accordance with the expectation
for mixed fission products.
The January 1955 land plant col-
lections, however, show 4& trend toward increasing activity
levels (Figure 9).
This could be due to 2 sampling error, but
might also be a reflection of greater availability of the fission
products to the plants asscelated with more rainfall during
late December to January.
The values for 4rrowroot collected on Rongelap Island in
January 1955 fell within the range of values for arrowroot from
the northern islands.
The same is true of algae collected at
gepthe of 10 to 25 fathoms in the vicinity of Kabelle and Rongelsp Islands.
However,
the maximum activity levels found in
Halimeca sp. and Caulerpa sp. from Rongelap are higher by a
facto: of about two than the maximum levels found in the same
species collected at Kabelle.
It appears likely then that al-
though maximum fallout occurred at the north end of the atoll,
the vadizactive materialis being redistributed throughout the
&toll,at teast in the deeper waters.
Decay rates of five individual samples of algae and land
plants collected in July and December 1954 indicate half-lives
ranging from 160 - 210 days during the period from December 1954
to April 1955.
A sample of coconut milk coliseeted at Kabslle
island in Decenber 1954, however, shows a haii’-life of approxiThe slopes of the decay curves of land and
i
use
Ca
mately thrce years.