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7. RECOMMENDATIONS
(1)
It is recommended that profiles of unsupported
210
Pb concentrations,
at other lagoon stations which have accumulations of finely divided sediments, be made to better understand the horizontal redistribution process.
(2)
Additional sediment sampling is recommended to better define the
the areal distribution of radionuclides around the craters, especially in
the northwest quadrant of the lagoon.
(3)
Because the distribution of radionuclides between the sediments and
bottom waters of the lagoon appear to be a valuable means of understanding
the initial distribution of radionuclides in the water column, it is
recommended that future sediment sampling be accompanied by a sampling of
the adjacent bottom waters.
(4)
An investigation of the physical-chemical properties of the parti-
culate material and associated radionuclides suspended in the water column
is recommended in order to better understand their origins, behavior and
cycling in the lagoon ecosystem.
An interesting approach to this problem
would be to measure, in pariculate material separated (by size) on millipore type filters used in series, the weight, proportion of organic
material, and the concentrations of radionuclides on the different sized
filters collected at a few selected lagoon and crater stations.
Such
measurements might be supplemented by leaching experiments and by S.E.M.
photography to identify the particle types.
(5)
Measurements of the total alpha radioactivity of a coralline
sample which has a known alpha disintegration rate is recommended to
empirically verify the presence of the fraction of alpha emitting radionuclides not accounted for in the Bravo crater sediment analyzed.