species Or risn are characterized by relating tissue concentrations to those in filtered seawater. For bottom-feeding fish, the values are lower at the lesser contaminated atolls than those values determined for the same species at the more contaminated atolls. These fish have the ability to lower their gut pH during feeding. When this occurs, there is a dissolution of a fraction of the ingested calcium carbonate containing radionuclides that were fixed or fused internally to the material during nuclear testing. Fractions of the radionuclides released during solution in carbonate matrix are available for passage across the gut wall. Amounts released to solution in the gut are proportional to the levels of contamination at the different atolls. Concentration factors for higher trophic level species, which do not rely on sediments or coral for their source of food, show no such trends between differentially contaminated atolls. A two-source model used to compute the internal concentrations is described. Americium-241 seems to be more biologically available than /sup 239,240/Pu to higher trophic level species from the lagoons, whereas at lower trophic levels the opposite seems to be the case. Cesium-137 is now the largest contributor of the small radiological dose to man from the marine fish pathway, weth the transuranics contributing from 2 to 30% of the total dose. 22 references, 1 figure, 19 tables. Major Descriptors: *AMERICIUM 241 ~- BODY BURDEN; *CESIUM 137 -- BODY BURDEN; *FISHES -- RADIONUCLIDE KINETICS; *PLUTONIUM 239 -- BODY BURDEN 7 *PLUTONIUM 240 -- BODY BURDEN; *STRONTIUM 90 -- BODY BURDEN Descriptors: BIOLOGICAL AVAILABILITY; COMPARATIVE EVALUATIONS; EXPERIMENTAL DATA; GENETIC VARIABILITY; MARSHALL ISLANDS; MATHEMATICAL MODELS Broader Terms: ACTINIDE ISOTOPES; ACTINIDE NUCLEI; ALKALI METAL ISOTOPES; ALKALINE EARTH ISOTOPES; ALPHA DECAY RADIOISOTOPES; AMERICIUM ISOTOPES; ANIMALS; AQUATIC ORGANISMS; BETA DECAY RADIOISOTOPES; BETA-MINUS DECAY RADIOISOTOPES; BIOLOGICAL VARIABILITY; CESIUM ISOTOPES; DATA; EVEN-EVEN NUCLEI; EVEN-ODD NUCLEI; HEAVY NUCLEI; INFORMATION; INTERMEDIATE MASS NUCLEI; ISLANDS; ISOTOPES; MICRONESIA; NUCLEI; NUMERICAL DATA; OCEANIA; ODD~-EVEN NUCLEI; PLUTONIUM ISOTOPES; RADIOISOTOPES; STRONTIUM ISOTOPES; VERTEBRATES; YEARS LIVING RADIOISOTOPES Subject Categories: 560162* -- Radionuclide Effects, Kinetics, & INIS Toxicology -- Animals, Plants, toxicology in animals, plants & microorganisms Subject Categories: C2120* Microorganisms, & Cells -- Radioisotope effects, kinetics, 10/5/452 (Item 152 from file: 103) 02052574 ERA-13-004390; EDB-87-180533 Author(s): Shingleton, K.L.; Cate, J.L.; Trent, M.G.; Robison, Title: Bikini Atoll ionizing radiation survey, May 1985-May 1986 Corporate Source: Lawrence Livermore National Lab., CA (USA) Publication Date: 1 Oct 1987 p 85 Report Number(s): & W.L. UCRL-53798 Order Number: DE88001322 Contract Number (DOE): W-7405-ENG-48 Document Type: Report Language: English Journal Announcement: NTS8712 Availability: NTIS, PC AO5/MF AOl. Subfile: NTS Abstracts). (NTIS); INS (US Atomindex input); TIC (Technical Information Center) Country of Origin: United States Country of Publication: United States ERA (Energy Research , Abstract: Between 1946 and 1958, the United States conducted 23 nuclear tests at ‘the. Bikini Atoll in the Marshall Islands, which resulted in extensive radioactive contamination of a number of islands in the atoll and prevented the timely resettlement of the native population. Although the external dose rates from beta and gamma radiation have been previdusly determined by aerial survey and a variety of ground measurement techniques, technical constraints limited the assessment of external beta dose rates that result from the /sup 137/Cs and /sup 5003198