FISSION-PRODUCT CYCLES IN AN AGRICULTURAL
SYSTEM. |. SAMPLE HETEROGENEITY
HOWARD A. HAWTHORNE
Laboratory of Nuclear Medicine and Radiation Biology,
University of California at Los Angeles, Los Angeles, California
ABSTRACT
The dispersion of “Sr and ''Cs within the components of a dairy farm
were
examined aS a preliminary step in developing mathematical
models of the system. The high variability in mass of the matrixes and
in the concentrations of Sr and "Cs nullified any assumption of general homogeneity within the system. Variations in matrix mass of
fission-product vectors were consistently smaller than variations in
Sr and ‘’Cs concentrations within the matrixes, soil, plants, and milk.
Models representing the movements of fission products among the
components of a food chain must account for fission-product dispersion
within matrixes and for variations in matrix mass.
SAMPLE HETEROGENEITY
An exploratory study was conducted to assess variability in the
different components of a small dairy farm through which “Sr and "Cs
pass before entering milk. The variations examined were those of radionuclide concentrations in soil, plants, and milk and variation in the
mass of these matrixes. The soil matrix was examined in threedimensional space. Variations in the isotopic burdens of plants and in
crop production were evaluated in two dimensions of space and the
dimension of time, and variations in the consumption of feed by cows
and its contamination levels were studied in the dimension of time, as
were the "Sr and '*"Ccs content of milk and its production. Heterogeneity
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