The present study provides a survey of relationships in current use to quantify sorption of reactive solutes by soil. Its purpose is to examine present concepts and to indicate active research directions. Both equilibrium and first‐order kinetic sorption models are reviewed. Equilibrium models discussed include the linear, Freundlich, Langmuir, two‐surface Langmuir, and competitive Langmuir isotherms. Kinetic sorption models reviewed are the reversible linear, reversible nonlinear, kinetic product, bilinear, mass transfer, Elovich, Fava and Eyring, and two‐site kinetic model.The models reviewed appear to provide a reasonably good basis for extrapolation and interpolation of data. There is a continuing need, however, to upgrade these methodologies as demand for accuracy and realism increases. It is expected that the state‐of‐the‐art review provided by this survey will assist in this process.

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The draft version of this report was distributed in March 1990. Only minor changes were made for this final version; substantial revisions to the draft were unnecessary.

The classic methodology for estimating dose to man from environmental tritium assumes that all tritium, whether organically bound or free, enters directly into man's free body water compartment and is uniformly distributed as tritiated water. This methodology ignores the fact that organically bound tritium in foodstuffs may be directly assimilated in the bound compartment of tissues without previous oxidation. A four-compartment model consisting of a free body water compartment, two organic compartments, and a small, rapidly metabolizing compartment is proposed. The utility of this model lies in the ability to input organically bound tritium directly into organic compartments representing tissue solids. The model will be used to illustrate the potential importance of organically bound tritium to cumulative dose estimates. It is found that organically bound tritium in foodstuffs can increase cumulative total body dose by a factor of 1.7-4.5 times the free body water dose alone, depending on the bound-to-loose ratio of tritium in the diet.

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