80
vielded 226 Ra/ 2344) ratios of 0.09, within the limits of the error term
alculated for the ratio, as given by Thurber et al. (op. cit.).
In contrast,
-rface sediments which were collected close to the craters and which con-
trained high concentrations of most radionuclides (those below the dotted line
in Table 13) gave higher 226 p45 /234y ratios.
The unusually high concentrations
of -?5pa {relative to uranium) in these later surface sediments may thus indi-
cate that they are ancient sediments which have been brought to the surface
and distributed in the lagoon from the detonation craters.
Although the
uranium concentration in the sediment from Station B-30 was not measured, the
high 226p4 concentration measured indicates that this sediment is also ancient
crater area material.
The distribution of 21056 (21055) concentrations measured in surface sediments 1s shown in Appendix II, Table 4.
In Appendix III, (Tables 1-5) are
found the 21055 measurements made on the surface (0-2 cm) sections of the sediment cores.
Nearly all of the high 2105, concentrations measured occur in
sediments collected rrom the most contaminated portions of the Jagoon.
How-
ever, this is not surprising considering the presence of old corals with high
226p4 concentrations tn the same area.
To “normalize” the 2105, data, the
226p, concentrations (Table 13) were subtracted from the 2105, concentrations
to find the concentration of unsupported 2105), in the sediments.
At the
station where data from surface grab and surface core sediments were available, the 210p., concentrations used were obtained by calculating a weighted
(by the measurement error) mean concentration of 21055,
concentration of unsupported 2105), calculated.
Table 14 shows the
The distribution of unsup-~
ported 2105), concentrations across the atoll] shows no correlation with either
the distribution of other radionuclides measured or with specific geographical
areas.
The range of concentrations is not high.
At the stations located in