Table 1 Lognormal median concentrations of 2**?*°Pu in fish tissues (pCi g-' dry weight) collected at Enewetak and Kwajalein atolls* Enewetak Atoll {all samples) All fish species Bone Muscle Gut 0.038 0.013) 0.45 (24) (123) (6) Surgeonfish Muscle Gut 0.028 0.019 (28) (26) Mullet Muscle Gut 0.014 0.75 (25) (19) Goatfish Muscle Gut 0.008 0.093 (2) (18) All other fish Bone Muscle Gut 0.038 0.009 0.25 (24) (49) (44) Kwajalein Atoll Meck Island Kwajalein Island 3) (1) (3) 0.086 0.023 0.051 0.02 0.03 (3) (2) 0.086 0.024 0.14 (3) (8) (1) 0.01 Enewetak Island (6) 0.01 0.53 0.42 (3) (2) 0.96 0.43 (h) (1) 0.40 0.41 (2) (1) (6) *See refs | and 5. +Values 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. 167 E 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 discrepancies between predicted and measured concentrations for fish muscle. SS La Excess plutonium at Kwajalein 167°20° North Pass ¢~” Roi-Namur | 5 4% 9 20’'N “ “muzu ‘ "hy eis, a would be that Kwajalein Lagoon contains significantly more “hy .. ON plutonium levels in the open ocean in this region. Unfortunately, our schedule did not allow time to collect fish on. Kwajalein Atoll. The water samples were analysed for 7°°-?4Pu and '°’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 7°°24°Py 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 woridwidefallout. At the time the Kwajalein water samples were being processed we werealso participating in an intercomparison exercise with Woods -Hole Oceanographic Institution to determine ‘, "3 Fea Enewetak Island oN > > Meck Island 2's i, aw 4“, Bigej Channel N 4 : od South Pass di Kwajalein Island equatorial surface waters, to provide information on the Table 2 “Sty ar An alternative explanation to account for these discrepancies 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 167° 40° 8 40’N Fig. 1 Locations of sampling sites (see Table 2). ~ 239,240Py Jevels 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~3, whereas ours for 10 samples was 0.70+0.30 pCim~3. 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 plutonium levels are somewhat lower in Kwajalein Lagoon than in Concentrations of °9*-?*°Pu and 1*°Cs (pCi m~*) in seawater in Kwajalein Lagoon and two locations in north equatorial waters Station* Depth (m) Collection date 1 I 2 3 3 4 5 10°26’N 166°31‘E 11°16'N 165°45’E Surface 44 Surface Surface 47 Surface Surface Surface Surface 5/10/75 §/10/75 5/08/75 5/08/75 5/08/75 5/08/75 6/14/75 6/15/75 6/15/75 *Kwajalein stations are shown in Fig. 1. 239.240 Py 0.33 0.87 0.29 0.26 0.33 0.54 0.52 0.36 0.53 (20)t (13) (27) (24) (25) (16) (18) (32) (23) 137(C5 137 144 I3E 127 129 129 132 132 143 *Values in parentheses are the lo counting errors expressed as percentages of the listed values. (3) (5) (5) (3) (3) (4) (4) (3) (4) 230.240 Py /237Cs5 0.0024 0.0060 0.0022 0.0020 0.0026 0.0041 0.0039 0.0027 (20) (14) (27) (24) (25) (16) (18) (32) 0.0037 (23)