Table 1
Lognormal median concentrations of ?*-?*°Pu in fish tissues (pCi g~' dry weight) collected at Enewetak and Kwajalein atolis®
Enewetak Atoll
(all samples)
All fish species
Kwajalein Atoll
Kwajalein Island
Bone
Muscle
Gut
0.038
0.013
0.45
(24)
(123)
(6)
0.086
0.023
0.051
Surgeonfish
Muscle
Gut
0.028
0.019
(28)
(26)
0.02
0.03
(3)
(2)
Mullet
Muscle
Gut
0.014
0.75
(25)
(19)
Goatfish
Muscle
Gut
0.008
0.093
(21)
(18)
All other fish
Bone
Muscle
Gut
0.038
0.009
0.25
(24)
(49)
(44)
0.086
0.024
0.14
(3)
(8)
a)
Meck Island
(3)
(11)
(3)
0.01
Enewetak Island
(6)
0.01
(6)
0.53
0.42
(3)
(2)
0.96
0.43
(1)
(1)
0.40
0.41
(2)
(i)
*See refs | and 5.
tValues in parentheses are numbers of samples analysed. Average muscle and gut values in pCi g~! dry weight can be converted to average
pCi g~? wet weight by dividing by 3.5.
concentrations in Table 1. This discrepancy cannot be accounted
for by any possible differences related to trophic levels or
feeding habits. A similar calculation also yields large dis-
l67°E
crepancies between predicted and measured concentrations for
167°40°
North Pass \ @“” Roi-Namur}
fish muscle.
neal EX.
“w ar oe “Le
Foe,
TE ade
Excess plutonium at Kwajalein
raf
+
eS.SS
9°20°N
a,
vay
eae,
Sh,
Psy
PO
ty Enewetak Island
s
.
Sy
:
+Z
An alternative explanation to account for these discrepancies
would be that Kwajalein Lagoon contains significantly more
plutonium in its environment than would be expected from
worldwide fallout levels alone. To test this possibility, 551
unfiltered water samples were collected during May and June
of 1975 from the locations shown in Fig. 1. During June, two
samples were also collected outside the Atoll in the north
equatorial surface waters, to provide information on the
plutonium levels in the open oceanin this region. Unfortunately,
our schedule did not allow time to collect fish on Kwajalein
Atoll.
The water samples were analysed for 23° 2Pu and 13’Cs
using the methods described in refs 9 and 10. Our analytical
results are shown in Table 2. Although the lagoon was not
sampled in great detail, the data are sufficient to show that the
average **-?49Pu concentration in Kwajalein Lagoon (0.45 +0.21
pCi m~*) is nearly the same as the mean for the surface water
of the ocean in the area, and that it agrees reasonably well with
the levels previously predicted from worldwide fallout.
At the time the Kwajalein water samples were being processed we werealso participating in an intercomparison exercise
with Woods Hole Oceanographic Institution to determine
Table 2
167°20°
et
V17
oN
a~ Meck Island
Ay 3"?
“oe Bigej Channel
South Pass 1Ao Kwajalein Island
8 40’ N
Fig. 1
Locations of sampling sites (see Table 2).
*
239-240Py, levels in replicate surface-water samples from one
location in the North Atlantic. The mean value for eight
samples from Woods Hole (V. T. Bowen, unpublished) was
0.63+0.16
pCi m-*,
whereas ours
for
10.
samples
was 0.70-—0.30 pCim~°. This analytical agreement (as
well as that in other national and international intercomparisons that we have completed) lends a measure of confidence
to our data. In addition, these comparative data show that, as
expected from worldwide depositional data!'!, average plu-
tonium levels are somewhat lower in Kwajalein Lagoon than in
Concentrations of ?**?4°Pu and !"Cs (pCi m~*) in seawater in Kwajalein Lagoon and two locations in north equatorial waters
Station*
Depth (m)
I
Surface
3
Surface
1
2
3
5/10/75
44
Surface
$/10/75
§/08/75
47
§/08/75
Surface
6/15/75
4
5
Surface
Surface
11°16°N 165°45’E
Surface
10°26'N 166°31'E
Collection date
*Kwajalein stations ave shown in Fig. 1.
5/08/75
§/08/75
6/14/75
6/15/75
239, 240Py
1 VCs
137
144
131
127
129
129
132
132
143
*Values in parentheses are the Io counting errors expressed as percentages of the listed values.
(3)
(5)
(5)
(3)
(3)
(4)
(4)
(3)
(4)
238, 240Py /I7Cs
0.0024 (20)
0.0060 (14)
0.0022 (27)
0.0020 (24)
0.0026 (25)
0.0041 (16)
0.0039 (18)
0.0027 (32)
0.0037 (23)