The water was counted for gross activity and was filtered for particulate size study. Two
methods were used for counting the water. In cases where the activity was considerably higher
than background, an aliquot of the water was evaporated (in a drying oven) to salt, which was
thea counted.
In cases where such treatment gave inaccurate counting rates, the water was
treated with ferric ammonium sulfate and ammonium hydroxide to carry down the radioactive
species. The precipitate thus obtained from 1 to 10 liters of water was then counted for beta
and gamma radiation.
Some of the samples were filtered through a series of graded filters in
order to determine if any relationship existed between particulate matter and total activity.
—_——
ee
~~.
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Standard chemical group separations of the Fe(OH); precipitates were begun aboard ship and
completed ashore at a later date. Decay curves were plotted for both beta and gammaradiation
where conditions permitted counting aboard ship.
The salinity of the samples was determined by
chlorinity analysis and was compared with gamma activity to see if any relationship existed between radioactivity and salinity with depth.
§.4.3 Particulate Analysis.
The particulate matter from sea water was filtered through
graded Schleicher and Schuell (SS) filters. A series of SS membrane filters were used ina
yacuum-filtration apparatus. These filters ranged in porosity from 1.0 to 0.1 microns. Fur-
ther filtration of the filtrate from the above series was accomplished with graded ultrafine SS
filters ranging from a mean porosity of 0.1 to 0.01 microns.
The water was filtered under a
pressure of 1,000 psi in an ultrafilter pressure device. Sea water was also filtered through
cellulose and Millipore filters to compare their retention and adsorption properties. Number
20 phytoplankton nets were used to filter the phytoplankton from the surface waters.
The re-
sulting hauls were filtered through a Millipore filter and counted for the beta and gamma activity.
Radioautographs were attempted from the filters in order to impress the image of the active
ee
particulate matter on film,
Kodak high-contrast lantern slides were used.
\
5.4.4 Sediment Analysis. A gravity-coring device was used to sample the ocean floor.
Lagoon sediments were collected with a bottom grab and by skin divers. The sediments were
counted for beta and gamma activity.
Radioautographs of vertical core sections were made to
determine the penetration of Ru!through the surface of the pelagic sediments.
5.4.5 Biological Sampling. Extensive sampling of zooplankton was made to determine the
gross contamination of the marine life inthe EPG. Plankton was netted with a 1-meter-diameter
net used to collect zooplankton from the surface to 300 meters. A 0.8-gram portion of the mixed
planktoa was dried on a copper planchet and counted for both beta and gamma activity. Decay
curves were run on the gross plankton. Individual organisms were selected from the mixed
samples, dried under an infrared lamp, and counted for radioactivity. Gamma energy spectrum
analysis and chemical group separations were run on gross zooplankton to identify specific
isotopes.
A varied assortment of flying fish, squid, lobsters, coconut crabs, water fowl, lagoon fish,
molluscs, algae, barnacles, and catcareous coral were obtained and assayed for fission products and induced radioactivity.
3.5 INSTRUMENTATION
The M/V Horizon was equipped with an elementary radiochemistry laboratory, which was
capable of collecting samples, weighing or measuring, drying or ashing of organic matter,
separation of periodic groups, and counting both beta and gammaradiation. Gamma energy
Spectra were studied with a single-channel, step-pulse-height analyzer. A 2,-inch, sodium
iodide, well-type crystal, bonded to a Dumont 6292 photomultiplier tube was used to detect the
gamma photons.
Gross beta counts were made with a 1.4 mg/cm? mica-end-window G-M tube driving a decade
Scaler. The tube was shielded by a 2-inch-thick, lead sample holder.
Gamma rays were counted with a 2-inch-lead-shielded, 1¥,-inch sodium iodide erystal, RCA
5819 photomultiplier tube, preamplifier, and decade scaler. Several laboratory survey meters
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