of solution concentrations used in a particular study. Note
that in this case the equilibrium Freundlich partition
coefficient, KF, is the same as the distribution
coefficient, Kd, and X/m equals S in Equation (3-1).
Neither Freundlich partition coefficients nor distribution
coefficients are universally transferable because they
depend heavily on both the properties of chemical compounds
and the characteristics of the soil matrix. Enormous
efforts have been devoted to making these relationships more
useful and easier to apply to soils with different
characteristics. Karickhoff et al. (1979) demonstrated that
for a dilute solution (i.e. concentration of the contaminant
less than half of its solubility in water), partition
coefficients based solely on organic carbon in the soil
matrix, Koc, correlate closely to KF/foc as
Kc = K / fc (3-3)
where f is the fraction of organic carbon in the soil
oc
matrix. This relationship ignores any influence of the soil
itself but does facilitate the use of partition coefficients
or distribution coefficients from the literature as long as
the fraction of organic carbon in the soils are documented.
Chiou et al. (1979) and Karickhoff et al. (1979) reported
that Koc could be related to water solubility. They also
reported a relationship of the octanol/water partition
coefficient, Kow (ml/g), as
log K = log K 0.21 (3-4)
log Koc 5 0.67 ow
log K = 5 0.67 log WS (3-5)
oc