IDENTIFICATION OF ALUMINUM SPECIES IN ACID FOREST SOIL SOLUTIONS ON THE BASIS OF Al

Abstract

The kinetics of Al: F complex formation was studied in standard solutions in the pH range 2.75 to 4.75, which is of interest in relation to acid forest soils in West Germany. Fluoride activities were monitored during the complexation reaction with an F-selective electrode. The observed reaction paths were related to the equilibrium composition of the solution at the beginning of the reaction. Kinetic equations were fitted to the data by least-squares techniques. These equations allow the estimation of Al3+ and Al:OH forms in solutions of otherwise unknown chemical composition. The technique was further applied to quantify the concentration of free Al-ionic forms in solutions containing ligands common the soil solution. The results support further use of the technique developed here to speciate Al in the soil solution.