Operation Castle, Project 2.7A, Radioactivity of Open-Sea Plankton Samples

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BEST AVAILABLE COPY Defense Technical Information Center DEFENSE LOGISTICS AGENCY Cameron Station • Alexandria, Virginia 22314 BEST AVAILABLE COPY

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BEST AVAILABLE COPY flctiriCDS or other data are used for any purpose other than In connection with a definitely related Government thereby incurs no responsibility, nor any obligation whatsoever; and the fact that the Govern ment nay have formulated, furnished, or In any way supplied the said drawings, specifications, cr other data is not to be regarded by Implication or other wise as in any nanaer licensing the holder or any other person or corporation, cr conveying any rights or permission to nanufacture, use or sell any J patented Invention that may in any way be related BEST AVAILABLE COPY

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BEST AVAILABLE COPY Report to the Scientific Directo/ RADIOACTIVITY OF OPEN-SEA PLANKTON SAMPLES Scrlpps Institution of Oceanography BEST AVAILABLE COPY

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BEST AVAILABLE COPY Project 2.7a 'was an outgrowth of Project 2-7, the genesis of which Is described in the Project 2.7 report. Reference 1. During the 2.7 surveys, samples of marine organisms of the deep sea were collected by Scripps Institution of Oceanography (SIO) and were later analyzed by SIO and the U.S. Naval Radiological Defense Laboratory (NRDL). It was Ihe objective of Castle 2.7a to ascertain and to report on the general relation ship pertinent to the uptake of fission products by the marine organisms collected during the 2.7 survey In order to form a background for more extensive tests on Operation Wigwam. Gross beta activities, beta absorption curves and gamma spectra were analyzed, after identification of the organisms. A radiochemical analysis was performed by NRDL. It was found: (1) that marine organisms concentrate activity from fallout fission pro ducts in the water by factors of the order of 1,000. (2) that the partition of fallout fission products In the ocean is profoundly influenced by biological processes and that a purely physical model Is inadequate to predict distribution, (3) that the feeding mechanism of the organism does not clearly determine the amount of activity assimilated, (4) that there is evidence of fractionation of Isotopes by different organisms, and (5) that there is some evidence that finely dispersed activity is retained more or less proportionally with the dry weight of the organism. BEST AVAILABLE COPY

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BEST AVAILABLE COPY Much time has passed since the Castle Operation when the effects of fallout upon the open sea were first studied by oceanographic methods. More recent field tests have contributed far more data concerning the radioactive contamination of marine organisms than could be collected during the hastily outfitted cruise of the U.S.S. SIOUX following Castle, Shot 5. Nevertheless the two small samples of plankton that were collected by the SIOUX were sufficiently impressive to influence the thinking of people making preparations for later operations, and, in particular, the thinking of people involved in the problem of oceanic disposal of atomic wastes. Today these specimens themselves do not appear so spectacular, nor have some of the hypotheses that guided their analyses been completely substantiated. It Is now common 1knowledge that marine organisms are notorious concentrators of radioactive debris from nuclear detonation; and biologists, radiochemists and oceanographers have acquired enough interest and experience to carry out we.l-organized and integrated research on the problems. For these reasons the original interim report has been re written and some of the conclusions have been left out. Critical original experimental data from field expeditions retains its value almost indefinitely, however, and this paper reports the first direct in situ evidence of the profound influence of deep sea organisms on the partition of radioactive debris from atomic weapons, and directly demonstrates the inadequacy of a model that accommodates only the physical processes of mixing, advectlon, etc. This fact Justifies a final report. The authors wish to point out that proper credit has not yet been directed to certain people who were largely responsible for the original conception of the expedition and outfitting of it so that it could be successful. It was Professor John D. Isaacs who, In fact, proposed that plankton samples be taken and who located and acquired the special net that was needed, as well as the other oceanographic gear, and it was to a great degree the scientific and administrative experience of Professor Isaacs and of Ur. Edwird Martel! that pulled the project together as an operational unit. It is almost impossible to be sure that proper credit la given to everyone who con tributed to this special aspect of the Castle project. The radioanalyses of Table 2 were the data transmitted to SIO by Dr. L.H. Werner with valuable comments. Dr. Edward D. Goldberg was responsible for tho beta and gamma measurements shown ou Table 1 and Figures 1, 2, and 3; the beta analyses were carried out at SIO but the gamma spectra were measured at NRDL. Dr. Marteil reviewed the preliminary report and demonstrated that these early, scanty, experimental findings could hardly justify the conclusions expressed. The authors con curred and the report has been revised extensively. BEST AVAILABLE COPY

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BEST AVAILABLE COPY BACKGROUND AND OBJECTIVES 9 General Character of Biological Samples------------- Characteristics of the Sea Water Masses Involved State and Size of Fission Particles in Sea Water 3 Gamma energy spectra —--------------------------------------------------------------------- 1 Beta Activities of Organisms from Castle -------------------------------------------- 3 The Physical State of Fission Product Elements in Sea Water Following BEST AVAILABLE COPY

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BEST AVAILABLE COPY RADIOACTIVITY OF OPEN-SEA PLANKTON SAMPLES BACKGROUND AND OBJECTIVES Immediately following Shot 5 of Operation Castlo In 1954 the Fleet Tug U.S.S. SIOUX manned by scientific personnel from NRDL and the Scrlpps Institution of Oceanography made a four-day long cruise through the oceanic area adjacent to Bikini. The extensive measurements of the pattern of gamma activity in the sea water were made and are the subject of a comprehensive report, Reference 1; and during the cruise, at two different stations, a net was lowered and a sample of the zooplankton population was taken. These zooplankton samples exhibited an Intense concentration of gamma activity over that of the surrounding water. This was immediately apparent from the effect that their presence in the specimen, jars had upon a portable gamma Indicator, in spite of relatively high back ground aboard the ship. The two bottles of plankton were immediately sent to NRDL and SIO for classification and analysis by biologists and radiochemists. The outcome is the subject of this report. The sajnples were collected with a standard silk zooplankton net, having a diameter of one meter, using the technique customary in biological oceanography. The net was lowered into the water at 50 meters per minute until 200 meters of wire had run out. The wire was then hauled in at 20 meters per minute. This technique collects the organisms from roughly 509 cubic meters of water, including all depths between 0 and about 140 The samples were received at SIO about one week after collection and wore then further preserved with for malin; most of the organisms were in good condition. Biological identification of the organisms was made at SIO. Objectives of the Laboratory Studies. How fission products are distributed in the ocean after a fallout is of importance to those planning weapons tests and disposal of atomic wastes at sea. The distribution within the marine biosphere is of special impor tance, because (1) certain marine zooplankton are known to migrate vertically and there fore could be significant vectors of fallout activity through the stable layers where water transport is much reduced; (2) the activity in organisms is in a critical material, potential foodstuffs. Among other things, it was decided to investigate the possibility that an organism’s activity was influenced by its feeding habits. General Character of Biological Samples. Nets of the type used, pass most of the phytoplankton and very smallest zooplanklers. Most of w'hat is caught is of visible size. Many of the small animals display their ability for movement by darting about the collec tion Jar. Certain large transparent passive gellatenous animals can be seen to contain smaller organisms, alive or dead. Since it is known that zooplankton depend ultimately BEST AVAILABLE COPY

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BEST AVAILABLE COPY upon the minute primary plants of the sea, it is certain that any catch of zooplankton must Include also whatever phytoplankton exist as undigested fodder. ClaBSiflcation of Organisms. Marine zoologists are able to recognize amongst the zodff.' m several characteristic modes of acquiring food, and it was found possible to separate the Castle catch into three sorts. The resulting splits admittedly were small, but this was nil that the catch afforded. Tne classifications generally used by biologists are as follow; (S) Setal; feeding with the aid of protruding bristles (setae), (R) Rapacious; seizing food agressively, and (T) Tentacular; gathering food by means of tentacles. Characteristics of the Sea Water Masses Involved. Although the two samples were collected many miles apart, there is oceanographic evidence that the samples came from similar water masses in the sense that no differences in the type of zooplankton might be expected. However, It has been estimated that fallout arrived at Station 6 when this water was about 180 miles from the shot center, whereas the fallout arrived at Station 8 when this water lay about 80 miles from ground zero. Thus the fallout particles at Station 6 likely were finer than those at Station 8. Both points lay more or less along the axis of the computed fallout pattern. Reference 1. The gamma intensity measured by a Geiger detector (submerged but near the surface) at Station Y - 8 was roughly 10 times as high as the intensity similarly measured at Station Y - 6. These and other measurements indicate that the Sample Y - 8 came from water about 10 times more active than the Sample Y - 6. There Is oceanographic evidence that substantially only Shot 5 contributed to the con tamination of the waters from which each sample was taken. Gross Beta Axtivlty Measurements. Gross beta activities of each type of feede : are compared in Table 1. An cad-window Geiger-I.Iriler counter having a window thickness of 1.4 mg/cm2 was used. The organisms vary widely in size and In weight so that activity has been expressed in Table 1 In terms of wet weight as well as in terms of dry weight Beta Absorption Analyses. Figure 1 compares the activities from three feeding typos in terms of attenuation caused by aluminum filters Interposed In front of the counter. A setal feeder and a rapacious feeder were studied as well as samples of fish larvae whose feeding habit was not classified. The types are identified in Table 1. Beta Decay Characteristics. Figure 2 compares the decay of beta activities in four kinds of plankton; the curves were not normalized in percent of initial activity because their slopes are very similar and their superimposition would cause a confusing graphical Gamma Spectra. The gamma spectra of three nelected plankton were obtained in the 70-channel gamma pulse analyser of NRDL and two are shown In Figure 3 along with the Instrumental background spectrum. It will be noted In Table 1 that both organisms are BEST AVAILABLE COPY

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BEST AVAILABLE COPY beta ABSCORION CURVES Absorber Thicknesf,, mg/cm of Aluminum of the setal feeding type. The third biological sample consisting of rapacious copepods produced a spectrum indistinguishable from background. Radiochemical Analyses. Table 2 lists the results of the radiochemical analyses carried out at NRO.L (Reference 2), and displays certain individual activities In terms of BEST AVAILABLE COPY

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BEST AVAILABLE COPY Ooyv After Oetonotion Figure 2 Beta decay curves. certain activity totals. Ttii= tabulation also is the result of the initial interest in the matte.' of how the various nuclides are distributed in sea water containing plankton. The total weights and volumes of the portion of the haul analysed here was not reported but they were contained in specimen bottles holding about 200 ml water v.tth plankton that, it Is believed, would havo a “drained volume” of about 1 to 2 ml. There fore in Tabic 2 the total activity per ml volume Is of the order of 1,000 times higher in BEST AVAILABLE COPY

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BEST AVAILABLE COPY Photon Energy in mev Figure 3 Gamma energy spectra the solid fraction (drained zooplankton) than In the filtrate. More details are given In Table 2 which lists the ratio of the specific activity of each fraction of tho organic material to that of the supernatent liquor. The analyses of sea water samples taken in this area are still considered classified data and cannot be discussed here in such a way as to give more information concerning the concentrating ability of plankton to iallout materials. Furthermore, the analysis of BEST AVAILABLE COPY

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BEST AVAILABLE COPY the samples of water taken in this area was reported in tarms of gamma activity making valid comparisons with Table 2 difficult. Table 2 compares the compositions of the radioactivity retained by two species o* marine organisms that were selected from the solid fraction mentioned in Table 2. Even from the meager data shown here, it can be seen that there are significant variations in the amounts and kinds of activity retained. State and Size of Fission Particles in Sea Water. Table 3 is taken from earlier laboratory experiments at NKDL by Greendale and Ballou (Reference 3) where fission products were vaporized in sea water. The four nuclides listed display some tendency to Type OrguUio Ho. TOUJ ■ Mat Calaaoid copepode 1 Fleh Larva 1 1^58 1.258 4.0 1.1 9,2 II t Flccee of algal detrltua — 722 “ (».0) 0.72 0-90 1.0 Collected 8 Oslracoda, small ft 1,121 140 at. l.X 1*0 1.0 R Copepoda, rapactoua 10 328 33 ai 0.33 1.1 1-0 •Co*irtts reduced to time itcount-.rig, 22 May 1854. + Efficiency of ihc Beta Cuunter was about 14 percent segregate between three states of dispersal; however, it must not be Inferred from these laboratory data alone that in the case of fallout into the sea and in the presence of living organisms these elements would be permanently partitioned in the maimer tabulated. Moreover, a living organism might possess an affinity for activity in quite a dUIereui kind and degree than would the same organism dead. Tabic 3 does not indicate the physical state of barium, but from its chemical and BEST AVAILABLE COPY

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BEST AVAILABLE COPY r^sic&i properties or.-s would c?3>cct it to behave much like strontium and some Indication of this is shown in Table 2. It io lotown that the size of fallout particles arc related to the distance from the explosion at which the fallout occurs; and that the moan particle size in general decreases as dlstaMCG Increases. It is most likely therefore that the particles arriving at Station Y - 8 (80 miles from ground zero) were larger than those arriving at Station Y - 6 (1B0 miles from ground zero at the time of arrival). However, no direct measurements were rondo, and numerical estimates of particle sizo require extensive qualification beyond the scope and classification of this paper. In …