roART a 7 mons Ry RONGELAP PEOPLE, FISH AND SOILS» 243 Table 3. Iron-55 content in goatfish (Mulloidichthys, sp.) and soil samplesfrom Rongelab Atoll. Number of Jish livers contributing to single, pooled sample analyzed are in parentheses; stable Fe and *¥e are expressed fer kilogram of wet tissue or per kilogram dry soil Content Location Rongelapislet Kabelle islet Rongelapislet Kabelle islet Collection date Sample Liver (20) Biological samples September 1959 Liver (7) Liver (10) Liver (71) September 1961 March 1963 August 1963 55Fe (Ci)* 4.04 0.68 1.40. 2.49 Stable Fe (g) 0.98 0.76 1.15 0.37 55Fe Fe (uCi) | g 4.1 0.9 1.2 6.7 Soils Kabelle islet Kabelic islet Rongelapislet Rongelapislet Soil Soil Soil Soil (0-2.5 em) (0-2.5 cm) (0-2.5 em) (0-2.5 cm)- August August March August 1959 1963 1959 1963 0.24 0.06 © 0.03 0.006 * Sample counting times were arranged to determine **Fe in biological samples to 5% at the 95% confidencelevel (2c); soilsamples to +5-20% at the 67% confidencelevel (1¢). Stable Fe determination, +10%at the 67% confidencelevel (1g). Activities are corrected to collection date. on the levels of Zn, Cs and *°Sr observed, plant detritus could significantly alter the stable 55Fe body burdens were probably small.- The iron content but not the ®5Fe activity. In this Rongelapese returned to the atoll in mid-July instance, activity per unit weight of soil is a 1957. Whole body counting and urinalysis better index of changes which occur as a result measurements one yearlater disclosed increased of input or loss than is specific activity. body burdens of several radionuclides, the most The decrease in ®5Fe specific activities in notable being 457Cs. It is probable that Fe Mulloidichthys, sp. (goatfish) at Rongelap bebody burdens increased similarly. ‘tween 1959-1961 corresponds to an ecological ‘The concentrations of*5Fe in a selected species half-life of 11 months, identical to that obof fish and in the calcareous soils are listed in served by Jexninos."4) Higher specific activities Table 3. Activity in the fish is based on wet may have occurred at earlier times; however, weights for comparison with previous work. estimates based only on exponential loss would The amount of sample that was available for not take into account possible retention and analysiswas smal} and therefore.it was necessary cycling of §5Fe within the lagoon, or the time to combine individual samples. This prevents Jag between deposition and maximum specific an estimate of the range of ®°5Fe concentrations activity in the aquatic biota. which occur between fish, i.e. the within The increase in specific activity of goatfish sample variation. The numberin parenthesis liver between late 1961 and mid 1°63 reflects in Table 2 for the biological samples indicates the increased environmental concentrations of the number offishes which contributed to the 552e resulting from testing nuclear devices in pooled, single sample analyzed. The **Fe 1961-1962. Introduction of this radionuclide values for soil samples collected in 1963 at both to Rongelap Atoll can occurboth by atmospheric Kabelle Islet and RongelapIslet are averages of fallout and by water transport of radioactivity samples collected at depth increments of 0-1.3 from oceanic regimes. The westward-moving and 1.3-2.5em. Specific activities are not North Equatorial Currentis comprised ofwaters given for soils since varying amountsof pre-1954 from northern latitudes where fallout from the Sorz1b4 +rime TRE ete . rr Mey ee we