Aluminium heterogeneous speciation in natural waters

Abstract

The presence of aluminium in natural waters is of major concern at present because of the potential threat for the health of a number of species, including humans. In natural water, aluminium exists in different forms depending on the concentrations of various other species, organic matter, the types of minerals, the pH, etc. The aluminium species in the natural water – gibbsite system is considered in this work. The main approaches for estimating of the individual concentrations of the aluminium species involve the use of reliable thermodynamic data, together with experimental measurements of free or total concentrations of major components. The new type of diagrams based on graphical and computerized methods, which quantitatively describe the distribution of soluble and insoluble, inorganic, and organic, and monomeric and polymeric aluminium species in heterogeneous aquatic systems is presented. This approach utilizes thermodynamic relationships coupled with original mass balance constraints, where the mineral phases are explicitly expressed. The factors influencing the distribution of soluble and insoluble aluminium species in aquatic systems were analyzed. The new type of developed diagrams may be used to interpret data obtained within the framework of water-quality monitoring programs.