9 miles of the shot island (Begallua, Engebi, Aomon), the averageof all the algae samples
from onestation was not significantly different from a similar average for any other station.
7 b
The samples collected at the islands beyond this area contained significantly less radioactivity, the least radioactivity being found at Japtan.
Pe
Table 4.3 — RADIOACTIVITY OF"ALL ALGAE SAMPLES BY ISLAND*
&
=
TE
Island
5a
¥ .
Preshot
-
Japtan
n
Av.
6
3
4
*
Igurin
5
¥
Rigilit
4
2
+
PS
Igurint
Rigili
Bogombogo
7
“~
Postshot
Min.
n
0.066
0.099
0.041
6
0.16
0.46
0.22
0.97
0.067
0.14
4
6
16
550
40
2,100
1.6
4.3
8
3
5,200
4,000
14,000
6,800
1,200
2,500
5
1,400
3,900
56
4
3,600
6,200
400
0.19
0.36
0.51
0.58
0.21
2
0.74
Bogallua
Engebi
Engebit
7
3.
8.2
8.4
21
11
0.18
6.2
12
(7.7
54
1.7
12
6
«9.8
3.5
51
9.8
0.087
0.20
Aomont
Runit
Runitt
0.3
6
15
Max.
Min.
0.70
0.22
38
6.8
4.1
28
0.24
Bogombogot
AomonAaraanbiru
11
0.075
Av.
~
Max.
0.37
9
4
110
92
250
250
13
26
* Measured in disintegrations per minute per gram (x 1000), wet sample.
{? Dredged samples.
4.3.2
Analysis by Species
Of the seven most commonspecies of algae collected, there is no species showing activity
which is consistently higher than that of any of the others. The radioactivity of the coralline
algae, which contain a large amount of calcareous matter, does not differ from that of succu-
lent forms for specimens at the same station. These data are presented in Table 4.4. When
the samples were combined into phytogenetic groups, still no difference in radioactivity between groups could be shown. This observation was also noted in the 1949 survey report.!
4.3.3
Radiochemical Analysis
Radiochemical analysis of the pretest sample from the Lake George area (Sec. 4.8) showed
that Ce" having a half life of 280 days, contributed 74 per cent of the radioactivity. Results
of radiochemical analyses of posttest samples of sand dredged off Rojoa Island and of three
algae collected in the lagoon 200 yd off Bogallua Island are given in Table 4.21.
From 85 to 96 per cent of the total activity of the algal samples is accounted for by the
presence of the highly insoluble fission products, i.e., cerium, ruthenium, zirconium, and the
trivalent rare earths. Since the algae are nct likely to take up these insoluble materials in
their normal physiological prrcesses, it seems very probable that mostof the activity is
present on the surface of the algae rather than in the cells themselves. This does not, however, rule out .he presence of some radioactive salts in the cell structure or in the cell sap.
It has been shown that Sris absorbed by plants,’ and it is generally known that calcium is
an essential element in plant metabolism. Thus it is highly probable that a portion of the
calcium-strontium fraction found in the analyses is in the protoplasm of the algae.
er
30
ee ee ee
=
:
eee
:
~