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)