68 Tewa site, has been transported along the reef perimeter masking the Tewa ratio signature in surface sediments in the Crater area environs. 5.1~4 Europium-155 The areal distribution of ments is shown in Figure 14. 155 Fu in lagoon surface sedi- The highest concentrations were found along the northern sector of the lagoon at Stations B-19 and B-18. At most other Stations across the lagoon, the areal distribution of 155 Eu is very similar to the distributions of 239+240 Pu. Considering the chronology of the testing schedule at Bikini, the short (1.91 year) physical half-life of this radionuclide may be responsible for both the relatively low Soe concentrations measured in Station B-30 sediments (assuming Baker test debris was sampled here), and the relatively high concentrations found in sediments in the north central sector of the lagoon. show similar 239+249, Puf 155 The nature in which large areas of the lagoon ~~Eu or 241 4,195 Eu ratios indicate that the distribu- tion of these three radionuclides from individual tests are similar. the relatively short half-life of 155 Further, Eu is useful in separating the extent to which debris produced at different times is distributed in areas containing radioactivity from several detonations. 5.1-5 Cesium-137 The distribution of in Figure 15, 137 Cs in lagoon sediments is shown The highest concentration of '376, measured was found in sedi- ments collected at Station P-20. The distribution of 23942405, 1376, ratios across the lagoon illustrates that at least two areal distributions of V37e, are responsible for the concentrations measured: one centered at Station B-20 in the northwest quadrant; and one centered in the Zuni Crater area. distribution of 239+240,,137 Pu/ The Cs ratios to the east of Station B-20 show a rapid increase from a ratio of 3.92 at Station B-20 to a ratio of 184 at