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TABLE IV
LEVELS OF Sr°°—yYAND Cs!” IN TERRESTRIAL SAMPLES IN AND NEAR THE
ENIWETOK TEST SITE
ee
Eniwetok Atoll*
Soil
Spi yea
|
dimije %
|
a
dry weight
Messerschmidia
Fimbristylis
Sandburrs
|
375
wet weight
wet weight
wet weight
OG
|
76
|
9.4
;
5.9
(C3137
d/m/g °%
242
11.9
2.0
7.9
|
|
667
3,303
100
|
|
3.8
83
86
86.8
Average
7.3
|
85
I
Rongelap Atoll
Seaevola leaves (March, 1958)**
|
(Average of 11 samples)
Pandanus fruit (August, 1958) **
Pandanus leaves
|
l
Pandanus trunk borings
aot
Kabelle Island (Rongelap Atoll) **
Pandanus fruit (August, 1958)
Pandanus leaves (August, 1958)
Pandanus stems (August, 1958)
Pandanus bark
(August, 1958)
|
|
|
!
|
|
26.7
4.6
3.1
33.7
95.4
3.5
71.4
28.6
6.5
0.37
|
5.4
|
32.4
92.6
1,2
|
49,2
|
4.6
!
|
Einiaetok Island (Rongelap Atoll) **
Pandanus fruit (August, 1958)
Pandanus leaves (August, 1958)
Average
|
|
7.0
1.6
!
i
77.0
1.4
15.9
:
38.7
* D.J. South, 1957 (unpublished)
** DJ. South manuscript
highest percentages of Sr®°—Y®° (71%), and Cs!37--Ba!3’m accounted for the
remaining 29%. Thus on land the radioisotopes of strontium and caesium
and their daughter products accounted for a significant fraction of the total
radioactivity in the plants. This is not the case in the sea, although these
isotopes have been considered to be also of primary importance in the contamination of marine organisms.
In a series of plankton samples collected at the Eniwetok Test Site in 1958
3 to 36 hours after contamination, the ratios of observed Sr® to expected
Sr®° based on the observed levels of Mo%®—Tc#9m, Tel32—[132, Zr95_Nb%,
Cel41__Pr!41, and Ba!4°—La}!4° were calculated. The results are shown in
Table V.
In the plankton collected three hours after contamination, no Sr® was
detected in the large plankton. The level of Sr® in the nannoplankton was,
on the average, 0.43 of that expected on the basis of the levels of the abovenamed isotopes. In plankton collected later, no detectable difference in ratios
of radioisotopes existed between the large and the small plankton. At 21
hours, Sr® existed at a level 0.06 of that expected, and at 36 hours 0.03 of
130
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