McKay, Donald. "Front matter" Multimedia Environmental Models ...

K QA thus can be calculated by the analogous equation,
©2001 CRC Press LLC
K QA = yK OA(r/1000)
where y is organic matter mass fraction. This is equivalent to Z Q = yZ O (r/1000),
where Z O is the chemical’s Z value in octanol and r is the aerosol density.
In summary, Z Q can be deduced using the above equation, using the simple oneparameter
expression for K QA or one of the two-parameter equations for K P. Bidleman
and Harner (2000) discuss the merits of these approaches in more detail.
5.5.6 Other Partition Coefficients
In principle, partition coefficients can be defined and correlated for any phase
of environmental interest, usually with respect to the fluid media air or water. For
example, vegetation or foliage-air partition coefficients K FA can be measured and
correlated against K OA. Since K FA is Z F/Z A and K OA is Z O/Z A, the correlation is
essentially of Z F versus Z O. Hiatt (1999) has suggested that, for foliage, K FA is
approximately 0.01 K OA, implying that Z F is about 0.01 Z O, or foliage has a content
of octanol-equivalent material of 1%.
It is thus possible to estimate Z values for chemicals in any phase of environmental
interest, provided that the appropriate partition coefficient has been measured
or can be estimated. Figure 5.5 summarizes the relationships between fugacity,
concentrations, partition coefficients, and Z values.
5.6 MULTIMEDIA PARTITIONING CALCULATIONS
5.6.1 The Partition Coefficient Method
The calculation of one phase concentration from another by the use of a simple
partition coefficient is the most direct and convenient method. Care must be taken
that the concentration units and the partition coefficient dimensions are consistent,
especially when dealing with solid phases. There may also be inadvertent inversion
of a partition coefficient, i.e., the use of K 12 instead of K 21. It is also possible to
deduce certain partition coefficients from others; e.g., if an air/water and a soil/water
partition coefficient are available, then the air/soil or soil/air partition coefficient can
be deduced as follows:
K AS = K AW/K SW
If we are treating 10 phases, then it is possible to define 9 independent interphase
partition coefficients, the 10th being dependent on the other 9. In principle,
with 10 phases, it is possible to define 90 partition coefficients, half of which are
reciprocals of the others. When dealing with very complex multicompartment envi-