RADIUM (pCi/gm)
0.05
Me gen ates er me
1, AMM ELAMbe tot Sk maT PE ne on
0.10
oO
PRET EERE
eetale eA ps
0
|
{
0.1
0.2
CALCIUM(gm/gm)
Fig. 8,—The variation in the concentration of radium with the degree of calcification for the Phaeophyceae
creases with increasing degree of calcification in the
Phaeophyceae (R = 0.81).
A similar analysis was performed for the relationship between the concentrations of radium and protein nitrogen. The values of the correlation coefficients
for the Chlorophyceae and Rhodophyceae were not
significantly greater than zero (P > 0.1).
However, for the Phaeophyceae, where there was a
significant inverse correlation between radium and
calcium, the value of the correlation coefficient (R =
0.69) was significant (P < 0.1) when all the experimental data were considered, and highly significant
(P < 0,005) when selected data were taken. Therefore, the concentration of radium by Phaeophyceae is
directly dependent on the concentration of protein ni-
trogen in the algae. The data and regression line are
shown in Figure 9.
As the thorium data were not sufficiently numerous,
further regression analysis was not applied. However,
sphtting of the data into subsets according to phyta
did not alter the conclusion that the concentration of
uranium in these algae increases with increasing cal-
cification and decreasing protein content, except per-
haps in the case of Phaeophyceae.
The lack of significant correlations for the Chlorophyceae between the concentrations of radium and
calcium or protein nitrogen may derive, in part, from
the fact that the sampling within this division was
biased toward those species which are highly calcified (Halimeda opuntia and Penicillus capitatus).
The deposition of radium in these two species is probably entirely due to coprecipitation with caleczum carbonate, as the concentration of organic material, par-
ticularly in the former species, is very low. If this is
the case, then the [Ra]/[Ca] ratio (pCi/g) should be a
constant. The [Ra]/[Ca] ratio should increase with decreasing content of inorganic material in the organism
if radium is being complexed by the organic fraction.
A comparison of the average values of the analytical data for these two species is shown in Table 4.
From these values it ean be seen that, while total
concentration of calcium in Penzcillus capitatus is
25% less than in Halimeda opuntia, and the concentration of total organic material or protein nitrogen