TABLE 1
Average values of radioisotopes in plankton from two surveys made during 1958
and one in 1956 (Marsh). The six samples collected during the period less than 48 hours
post-shot were from one detonation. The four samples collected at greater than one week
had been contaminated by fallout from several nuclear devices. The five samples taken
approximately six weeks after contamination had been subjected to radioactive fallout
from several detonations.
A
Rehoboth
half-life
Mo**—Tc##m
|
Cel41__Ppr!41
Cel#4._Ppri44
Rul%83__Rhp!03 |
Ruls_Rh195
Ruts.R106 f
Ba!49__Ta148
12.8 d
77h
65d
Sr§9—_Syroa
50d, 28 y
C5187
26.6 ¥
Np?
U3?
Co4?
2.3d
6.8d
270d
Coss
Cot?
Zn%
Fess
Fe!
Mn*4
33d
285d
40d
4.5h, 36.3h
ly
Tel32__J132
Zr®5_Np*
|
66h
71d
B.2y
245d
2.6y
|
45d
291d
Surve
< 48 hours
|
12
2
<1
|
;
1
Collett
23
0
0
0
0
0
0
|
0
2
0
0
0
0
1
0
5
69
3
0
|
0
3
8
1
| Marsh Survey
Surve
>l1 weok
|
0
0
1.4
|
|
|
|
33
3
3
15
1
0
|
|
5
0
6
2
2
7
6 weeks
0
0
20
|
|
0
0
0
0
9
140
l
|
25
|
24
!
0
<1
one week after contamination, these radioelements comprised 62% of the
total radioactivity, and at the end of six weeks accounted for 74°, of the
contamination associated with the plankton.
The two anions accumulated by plankton (Zr?°—Nb*®* and Ru1®*—Rh!°)
probably follow the metabolic path of some chemically similar anion or
anions normally present in the marine environment. Evidence that radioactive anions are not retained per se is found in observations on the uptake
by plankton of a radioactive anion with no known metabolic function.
In an oceanic survey made in 1958, Lowman ef al (19) found a neutron-
induced radioisotope of tungsten, W185, for the first time. The isotope was
found in high amount in water and plankton (~50° of the total activity)
in an area of high total radioactivity about 180 miles in diameter. About
one-half of the W148> in the plankton was associated with silica, probably
from the skeletons of marine diatoms.
Almost all the radioactivity in the water samples was contributed by
Zr*5— Nb*> and W185, A major part of the material containing the latter radioelement in the water samples passed througha filter with a pore size of 0.45 p.
A second survey was conducted three weeks later. During the time between
the two surveys the centre of contamination moved 150 miles to the WSW,
a net advance of 7.3 miles per day. In plankton samples collected during
the second survey no W?!* was found, although almost all the radioactivity
122