-aane meme meee eee ee SSESeS very appreciably with depth. off of Eneu and Bikini The results of recent studies down to 100 cm appear to be showing a similar result and will be fully reported on in Appendices A and B. “It is therefore anticipated that sediment dredged from the bottom landfill of the lagoon offers a should plans require them. convenient source of backfill and The sandy bottom is generally flat and thus suitable for dredging, but numerous coral heads emerge, some of which - may exceed 1 km in diameter and stand more than 30 m high (Appendix A). 2.2 Islands The islands of the atoll size and in contamination. (Figure 2, Tables 1, 2) vary greatly in Only two of them are larger than 1 km? ; Bikini (2.4 km*) and Eneu (1.2 km¢). 2.2.1 Soil Composition. distribution in depth fall into two major classes. extractable potassium and of total fall off with Table 3. to depth to The major elements become judged by their The concentrations of phosphorus, nitrogen, and organic matter | small below 50 cm (20 in.) as shown in Cesium-137 follows this pattern (Tables 2 and 3) and is thought be associated concentrations of with the organic nonradioactive matter. strontium On and the other calcium are hand, the practically constant, and that of magnesium rises with depth. 2.2.2 Radioactive Contamination. The transuranic plutonium-239, -240 and americium-241 contribute less than the 30-year cumulative dose because ‘and their activity in the soil on Bikini elements .08 percent to they are scarcely taken up by plants is low (6). Their combined surface activity is about 17 pCi/g, on Eneu about 1.3 pCi/g, both well below the transuranic standard of 40 pCi/g employed at Enewetak (13N). The two major radioactive cesium-137 and strontium-90, present in soil 5000018 | 19 contaminants today are at roughly the same range of