28
27
concentrations in the lagoon.
given in Table 5.
A summary of the mean concentrations is
In 1972 the average 23942405, concentration in the
lagoon was determined for 34 unfiltered surface and bottom samples.
more detailed water sampling program was conducted in 1974,
(No78c).
A
In 1976, a
smaller number of water samples were collected around the perimeter of
the lagoon 2 km off the shore of the reef.
low activity sea water contained in dialysis bags is achieved in 3 da
to the environmental waters has very solute-like characteristics.
In the
It ts
tempting to suggest, considering the environment, that the remohilijzed
chemical species is some form of carbonate complex,
Water samples collected
during 1974 and 1976 were filtered through l-um filters.
These characteristics suggest that the plutonium remobilized
The average concentration cf total
2394240, uoin
the water was
essentially the same in 1972 and 1974 but a marked dectcase was noted
discussion to follow, the estimated average soluble 2394240),
during 1976.
concentrations shown in Table 5 refers to material passing through a
filterable material in the lagoon doubled over the mean 1974 level and
l-um filter.
the mean soluble concentration was reduced to half.
During July 1974, the soluble 229249 Pu
in concentration from 2 to 75 fCi/l.
in the lagoon water ranged
The percentage of the total
activity associated with the filterable material in the water samples
during 1974 and 1976 ranged from 2 to 54% and from 12 to 94%,
vespectively,
The concentrations of plutonium radionuclides in solution
above fallout background concentrations in the lagoon water is direct
evidence of the remobilization of transuranics from the solid phases of
the environment.
Dissolved plutonium released from the sediments of
Cactus Crater was traced for considerable distances along the reef by a
plutonium radionuclide balance, involving the change in the
samples were collected tn 1976 than in 1974,
During the 1974 program,
samples were taken at stations throughout the lagoon, whereas the 15976
samplings were restricted to locations only 2 km from the reef.
23942405, concentrations were found in water samples frov
The dissolved
plutonium passes readily through dialysis membranes (No78c),
Equilitration between dissolved plutonium in the crater sea water and
Sisilar
the few 1974
locations resampled in 1976, which suggests that any corputed rean
concentration in the lagoon is contingent on the number and locetier of
samples.
The rean
2
238, 2594240,
u ratio in the lagoon water samples
1972, 1974, and 1976 were virtually the same.
Difference:
in
in sarple
ratios between soluble and particulate phases were noted sometimes, but
stations were
not significantly different.
The dissolved plutonium moves in solution apparently without
interacting with the sediments deposits during transport.
Forty percent fewer
the average ratios associated with the two phases from all
2385, 2394240, ratio in the water, and dyes to trace the crater water
(No78c).
In 1976, the average concentration associatcd with the
During 1974 and 1976, 1.5 and 0.7 Ci of
239+240,, u,
respectively,
were found in solution and 0.?/7 and 0.53 Ci were assuctoted with
particulate material.
ef
These latter quantities represent
the plutonium inventory fn the surface sediment and
less than o.
Tess
Vw
than O.04%