Chromatography in geology
A typical example for the application of models and experimental methods of chromatography for geologic materials (e.g. soil, sediment) is the $K_\mathrm d$ model, which can be used for understanding the long-term behaviour of contaminants in the subsurface environment (e.g. the rooting zone of crops).

The parameter $K_\mathrm d$ is the partition coefficient, i.e. the ratio of the concentration of a contaminant sorbed on a specified solid phase (e.g. soil) to the concentration in a specified liquid phase (e.g. groundwater): 

$$K_\mathrm d=\frac{\text{concentration in solid phase (per kg)}}{\text{concentration in liquid phase (per l)}}$$

The partition coefficient $K_\mathrm d$ can be used to calculate the retention factor $k$:

$$k=\frac\rho\varepsilon K_\mathrm d$$

where
$\rho$ is the dry bulk density of the solid phase, and
$\varepsilon$ is the total porosity of the solid phase.
Typical values for soil are $\rho=1.4\ \mathrm{kg\ l^{-1}}$ and $\varepsilon=0.3$.

This parameter is related to the retardation factor $R_\mathrm F$:

$$R_\mathrm F=\frac1{k+1}$$

The retardation factor $R_\mathrm F$ corresponds to the ratio of the distance travelled by the contaminant to the distance simultaneously travelled by the mobile liquid phase:

$$R_\mathrm F=\frac{v_\text{contaminant}}{v_\text{mobile phase}}$$

For example, if the annual precipitation exceeds the evaporation by $300\ \mathrm{mm}$ and the porosity of the soil is about $\varepsilon=0.3$, the drainage water travels with an average velocity of $v_\text{mobile phase}=100\ \mathrm{cm\ a^{-1}}$ downward through the soil.

Assuming a mean value for the partition coefficient of plutonium in all soils of 

$$K_\mathrm d=7.4\times10^2\ \mathrm{l\ kg^{-1}}$$

the corresponding retention factor is

$$\begin{align}
k&amp;=\frac\rho\varepsilon K_\mathrm d\\[6pt]
&amp;=\frac{1.4\ \mathrm{kg\ l^{-1}}}{0.3}7.4\times10^2\ \mathrm{l\ kg^{-1}}\\[6pt]
&amp;=3.5\times10^3
\end{align}$$

and the retardation factor is

$$\begin{align}
R_\mathrm F&amp;=\frac1{k+1}\\[6pt]
&amp;=\frac1{\frac\rho\varepsilon K_\mathrm d+1}\\[6pt]
&amp;=\frac1{\frac{1.4\ \mathrm{kg\ l^{-1}}}{0.3}7.4\times10^2\ \mathrm{l\ kg^{-1}}+1}\\[6pt]
&amp;=2.9\times10^{-4}
\end{align}$$

Therefore, the migration rate is

$$\begin{align}
v_\text{contaminant}&amp;=R_\mathrm F\cdot v_\text{mobile phase}\\[6pt]
&amp;=2.9\times10^{-4}\times100\ \mathrm{cm\ a^{-1}}\\[6pt]
&amp;=0.029\ \mathrm{cm\ a^{-1}}
\end{align}$$

i.e. a downward migration of $1\ \mathrm{cm}$ takes about 35 years.