pouvoir d'échange cationique

CONT: [...] l'ère industrielle est venue accentuer le processus d'acidification des sols par son apport additionnel de dépôts acides. Certains effets ont été observés à partir d'expériences menées en laboratoire et dans des écosystèmes forestiers : [...]. La capacité d'échange cationique du sol (CEC), c'est-à-dire la capacité du sol à retenir les cations, diminue avec l'augmentation de l'acidité.

CONT: Within the soil there are metallic as well as hydrogen cations. There is an equilibrium between the cations and the negatively charged colloids on which they are absorbed. The total amount absorbed is called the cation exchange capacity or CEC and varies especially with the clay content and the amount of organic matter. The proportion of the metallic cations in the total CEC of the soil is the base saturation, which may afford a suitable measure of the acidity of the soil. There have been numerous methods used to determine the CEC and the base saturation of soils.
OBS: ... It is expressed in milliequivalents per 100 g of soil or other adsorbing materials such as clay.