dtope. ned na ze s. for for ton mmas emitted, per gram, of biological specimens containing the same nuclides. ce! and Ru'® were used as standards for comparison to the activity of the sediments and coral. The gammapulse height analyzer was calibrated for energies and efficiencies using a series of Ce, Ru, Cg8" Zn85, Cof’, K*, and Ra?” standards. The error of standardization for the number of gammas emitted per source was less than 10 percent. The accuracy of the conversion of gammas per minute to microcuries depends upon the currently accepted values for the nuclear level schemes of the isotopes (References 9, 10 and 11). 1.5.4 Preparation of Samples. The samples to be counted for radioactivity were weighed, dried at 110 C, in some cases ashed, and counted on aluminum or stainless stee] planchets. The samples for beta analysis were generally ashed to as small a volume as possible. The samples for gamma analysis were usually counted dry; how- ever, for chemical analysis, or for reducing the volume of large specimens, they were ashed. Samples of sea water were collected, filtered through millipore filters, evaporated to dryness and counted for beta and gammaactivities. Millipore filters were also as- sayed. Large volumes of water of low activity were treated with a ferric hydroxide and barium carbonate precipitation to carry down the less soluble fission products in a sma)] mass of carrier (Reference 12). The zooplankton samples, in most cases, were assayed without sorting into like kinds of organisms. The bulk of these samples consisted of smal] crustaceans. Large, individual animals were removed for separate assay. Upon completion of gross counting, all the dried zooplankton samples were combined and ashed in HC1Q, and HNO, acids. _The ashed mixture was then analyzed for specific isotopes by gamma energy analysis. The results were then substantiated by hydrogen sulfide chemical group separation. Large marine organisms were either ashed whole or their various organs dissected for determination of the distribution of activity within the organism. The pbytoplankton and suspended sediments were filtered on a millipore filter and counted directly. Self absorption was negligible because of the smal} volume of matter present on each filter; however, the small mass introduced errors in the determination of the weight of the particulate matter. ‘The bottom sediments were weighed, dried, and counted under conditions of standard geometry for the total gamma photons emitted per unit mass of dry sample. The pelagic.cores were frozen, sliced into 3-mm sections, weighed, dried, and counted for gross gamma count and for gamma energy spectrum. Samples of the air-borne particulate matter taken over the lagoons and over the open sea on millipore filters were counted without further preparation. 1.5.5 Chemical Separations. In order to substantiate the gamma energy spectrum analysis, samples showing different gamma energy peaks were dried, then wet ashed with nitric and perchloric acid. The resulting solutions were separated into hydrogen sulfide groups (References 12 and 13). Each H,S group was reexamined with the pulse height analyzer and then was purified into the suspected element (References 13 and 14) and counted for beta and gammaactivities. 1.5.6 Reporting of Data. The water sample results are reported as gamma rays emitted per liter of sea water compared to a Co® and Zn®standard. The instrument i9