tetAE about 100 yds. to 150 yds. southwest of the position of LSM-60.... report and Report, Both Figure (which Figures C-2 and 27 of Enclosure shows the C-3 increase of the present F of the Crossroads after Baker day) are comparable, essential agreement. The thickness in depth of water however, and in of the mud layer (Figure C-2 and Figure C-3), of the other layers of disturbed and redeposited sediment (Figure C-3), and the increase in depth of water as measured last summer, all show a symmetrical distribution, elongated to the southwest. The radioactivity of the bottom material in the target area is concentrated in the top (mud) layer of re-deposited sediment. Though the second and third layers show some radioactivity, and even the superficial layer of normal sediment outside the mud area is weakly radioactive in many places, over 90% of the plutonium and fission products are in the mud. Therefore, an attempt has been made to estimate the volume and weight of this material. Owing to the difficulty in penetrating the coarse Halimeda debris with the coring instrument, and the restrictions imposed on the location of cores by sunken ships and by diving operations from COUGLA (ASR-S), the distribution and number of cores was not ideal for this purpose. — With the additional information furnished by small bottom samples, however, a rough approximation is possible. * Appendix Figure Numbers replace original report. Shown on one year activities Table C-3 are following the the calculated BAKER Test. radioisotope relative If these calculated data represent the relative radioisotopic presence in the cored mud samples (see Table C-4) taken from the BAKER test area one year following the test, then one can. project the current level of specific activity in 1984 as shown in Table C-3 based on half-life calculations. the remain radioisotopes fixed in the This mud assessment assumes although there was that some speculation by researchers during the resurvey that Sr90 and Cs!37 would be leached out because of their solubility in sea water. little has been leached (see Appendix diminished gradient. 000087 C-6 B); however, We believe that very there should be a