66 239+240,,, Pu/~ ,241 Am ratios tend to exceed 2.0. In Zuni Crater and Station B-30 surface sediments, atypical ratios of 7.1] and 6.0 were found, and at Station 8-10 on the outer reef slope, the calculated ratio is 14.0. The different. ratios measured may reflect the signatures of debris from different devices tested in the southern and eastern areas of the atoll. 5.1-3 Plutonium-238 The distribution of 2385), in surface sediments across the lagoon (Fig. 13) is radically different from the distribution of 23942405, or 24) Am. The concentrations of 238 Pu found in Bravo and Zuni craters were significantly higher than the concentrations found in any lagoon sediments. The 2385, concentration in surface sediment from Bravo Crater decreased rapidly towards the N.E. from a high value in the center of the crater. This areal concentration gradient may be part of the pattern extending alona the northwestern reef of the lagoon. Surface sediments in the central lagoon appear nearly uniformly contaminated with 238 Pu. The low 239+240 Pu ratios found in Zuni Crater sediments easily identified debris from this detonation from any other observed in the lagoon. and high 2394240 The low radionuclide concentrations pu/?>8py ratios found in sediments directly north of the Zuni Crater illustrates the large concentration gradients that can result in sediments near a large test. Figure 13 also shows that lagoon sediments south of the Tewa test site contain unusually low concentrations of 238 Pu,relative to 2394240 Pu. Since 23942405 2385, ratios are not high in surface sediments from Bravo Crater, it seems likely that at Teast one of the origins of this plutonium debris with large isotope ratios is from the 5-MT Tewa test detonated in 1956. this observation can be substantiated by other evidence, it should follow that low 23942405 | 2385, ratio material, probably from the east of the If