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Experimental
Sampling Method
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Most of the soils for fallout documentation and uptake studies
are
collected by Dre Lo T. Alexander cf the United States Department of
non
Agriculture.
A description of the sampling procedure is given in
e
-
section 6.1 of the Appendix.
Preparation of the Sample
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The total soil sample is air-dried or placed in a 100°C oven
crushed, including rocks and vegetative material, to an aggregate size
fine enough to be biended efficiently.
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The entire semple is then ground and
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for about 12 hours, then weighed,
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Extraction and Separation
Strontium carrier (200 milligrams) and strontium=-85 tracer
(about 500,000 d/m) are added to a weighed sample aliquot (500 grams).
°
The aliquot is stirred with 6 M hydrochloric acid (1 liter) at room
temperature for approximately 40 minutes and the extract is filtered and
evaporated to a small volume.
leached organic material.
Nitric acid is added to decompose the
After evaporation, most of the leached silica
is dehydrated and is removed by filtration.
An oxalate precipitation is
carried out at pH 5.5 to precipitate the alkaline earths and leave iron
in solution.
Successive fuming nitric acid separations are performed
until essentially all of the calcium is separsted fecn the strontium and
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