Etude de la répartition des charges sur les surfaces des particules argileuses

Laudelout H. Etude de la répartition des charges sur les surfaces des particules argileuses. In: Bulletin du Groupe français des argiles. Tome 9, nouvelle série n°4, 1957. pp. 61-65

Biogeochemistry of calcium in a broad-leaved forest ecosystem

International audienceThis study of the biogeochemical cycle of Ca has been carried out in an oak-hornbeam forest ecosystem on a soil derived from the alteration of Famennian (upper Devonian) shales. The physical nature of the geologic substrate made it possible to use the watershed-ecosystem approach by monitoring the loss of Ca by streamflow. Input of hydrogen ions and Ca from rain were average as well as that of mineral nitrogen of which 50% was ammonium-N. Modelling the biogeochemical cycle of Ca in this ecosystem proved to be difficult owing to the heterogeneity of the geologic substrate. The cationic denudation occured mostly with bicarbonate ion as a carrier of the base cations towards the streamflow. Seasonal effects on streamwater cationic composition were in relation to maximal soil respiration occuring in the autumn. In addition to this effect, the electrolyte concentration of streamwater was determined by rain and by changes in concentration of the soil solution either by evapotranspiration or by freezing. In spite of widely fluctuating values of flow rate, the concentration of the streamflow remained constant within a factor of two or at the most three. The mechanism underlying this buffering action of the soil on the concentration of the solution flowing through it, was shown to be related to ion-exchange processes

Rôle de l'ion hydrogène dans les réactions d'échange ionique des argiles

Martin Hervé, Laudelout H. Rôle de l'ion hydrogène dans les réactions d'échange ionique des argiles. In: Bulletin du Groupe français des argiles. Tome 11, nouvelle série n°6, 1959. pp. 21-24