and organ or tissue being considered.
When compared by rank-
ing within each of the nineteen classes of items in Table 8,
the stations fall into the following decreasing order of radioactivity:
Japtan.
Bogallua, Engebi, Aaraanbiru, Rigili, Runit, Igurin,
The giant clam, Tridacna, was the only species col-
lected at every station.
Comparison of individual tissues
of this clam at each station is made in Figure 5.
The specific
activity relative to Igurin is shown for gill, mantle, muscle,
and digestive gland ("liver").
Whichever tissue is considered,
the ranking of the stations remains the same.
Japtan is not
included since several of the counts were background, hence
the ratios are meaningless,
every case less than one.
and the relative activity was
in
Included in Figure 5 are the rela-
tive activities of beach sand or soil and bottom sand from
each station.
The latter has a higher relative,
specific activ-
ity at Engebi than at Bogallua while the reverse is true with
the giant clam tissues.
No landing was made at Bogallua, con-.
sequently no beach sand is available from that station.
Bot-
tom sand was taken from sea cucumber guts, usually Holothuria
atra.
This can be considered a random sample of the bottom
sand since H. atra shows no selectivity in its ingestion of
bottom materials.3>
This difference between Engebi and Bogal-
37
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