816 RADIONUCLIDES IN MARINE PROTEIN CONCENTRATES College Park, Maryland. Gamma-rayemitting radionuclides were analyzed as received by counting 100-g aliquots of the concentrate (in duplicate) using NaI (TI) detection systems. Tron-55 was determined by chemically isolating the iron in the sample! and then measuring the 5.9keV X-ray which results from the deexcitation of its daughter, 5\in. Polonium-210 and ™°Pb were determined as previously described. Polonium-208 and #!2Pb were used as vield monitors to account for anvlosses which occurred during chemical processing steps. Measurement of the alpha radioactivity was done using alpha spectrometry with surface barricr diodes. “Trace element analyses for all elements except. iron were performed by atomic absorption spectrometry. Tron was determined colorimetrically, using O-phenanthrolein as the color-forming agent. Duplicate 20-g¢ samples of concentrate were wet ashed in redistilled. reagent grade concentrated nitric and perchloric acids or dry ashed in a muffle furnace at 160 C, depending upon the volatility of the element of interest. For the trace elements Co, Cu, Zn, Fe, Ag and Mn, dry ashing techniques were employed. For Cd and Pb, wet ashing with concentrated acids is preferred. Elemental concentrations were determined by the method of standard additions (Pb, Mn, Zn) or by coinparing sample absorbances with those prepared from standard solutions (Ag, Cd, Co, Cu). All radiometric data have been decay corrected to collection dates and the errors associated with these measurements are the standard errors (lo) derived from astatistical analy >is of the sample and background counting rates. The errors associated with the stable element analyses approach +5°% (based on agreements between duplicate samples and on samples to which known amounts of trace clements have been added). RADIOACTIVITY MEASUREMENTS The results of our radioactivity measurements are presented in ‘Vable 1. ‘There are significant diferences between the radionnclide content of these protein concentrates and those reported earlicr.@) In general, 7's values for concentrates prepared from surface feeding fishes are not appreciably diiicrent from those preparcd from inshore benthic fishes. Manganese-54 values are lower (possibly due to physical decay) while Fe values are generally higher. The “Sr concentration of all the concentrates was <0.05 dis/min/g dry weight. Lead-210 and 210Po values are comparable to those reported earlicr, with the notable exception of the anchovy taken off the Southern California coast. The value of 57.7 + 0.5 dis/min/g dry weight anchovy concentrate was confirmed by the analysis of an aliquot of this sample by C. W. Sill of the National Reactor Testing Station. This unusually high value wasat first surprising, and we therefore analyzed various organs (pooled and individual) of fresh anchovy (Engraulis mordax) and saury (Cololabis saira) to determine the distribution of the 7!°Po, “10Ph and stable Pb in these fishes. Both species represent pelagic fishes whose dict consists mainly of planktonic crustacea.(6? Table 2 clearly shows that in these fishes the majority of the #°Po and 7!°Pbactivity, as well as stable lead, is found in the internal organs, principallythe liver, bone, stomach contents and viscera (neart, intestine, spleen, kidnev, stomach and gonad). The number in parenthesis indicates the number of specimens analyzed. The valucs of ?}°Po observed makes the 7°Po content of the anchovy concentrate less surprising. Mlorcover, the stable lead content of the anchovy bone and liver substantiates the high stable lead value found in the anchovy concentrate. Vhe lead specific activities (dis./ min 7!8Pb/uge Pb) of anchovytissue range from G.08 to 0.3, with the lead specific activity of the anchovy concentrate being 0.09. These values, and those of the saury and other concentrates analyzed here, approximate the range of lead specilic activities found by Ter [sar ef al.,‘® in their measurements of rain waters collected in the mid-western United States. SHANNON ef al.930 have recently summarized their measurements of alpha radioactivity in marine organisms and water collected in South Africa. Although Shannon did not determine the partitioning of either 3!’Pb or “19P6 into the various organs of the pelagic fishes analyzed, he did onserve a mean 7!°Po/ 49Pb activity ratio of 157 for whole fishes. Our *°Po/6Pb activity ratios for the internal organs of anchovy and saury reported in Table 3 uM , qe .