3. Retention of plant protection products at the soil/water interface

Pesticide retention in soils involves adsorption/desorption processes at the solid/solution interface. Adsorption is a surface process corresponding to the passage of a species in solution over a solid surface. The species in solution is called the adsorbate, and the solid surface represents the adsorbent. The opposite process, corresponding to the release of an adsorbed species into solution, is desorption. Adsorption and desorption can be grouped together under the general term sorption.

There are two methods for studying the retention of a pesticide on soil:

• the equilibrium batch or static method;

• the column or dynamic method.

The quantities adsorbed onto the soil are most often obtained indirectly, by differentiating between the initial and final...