METAL SOLUBILITY AND PATHWAYS IN ACIDIFIED FOREST ECOSYSTEMS OF SOUTH SWEDEN

Considerable decreases in pH and base saturation have occurred during the last decades both in the upper and in the lower horizons of natural and seminatural soils of northwestern Europe, and are particularly well documented in southern Scandinavia. Increased fluxes of strong mineral acids, partly or mainly derived from atmospheric deposition, seem to be the main reason for these changes. The solubility of aluminium, base cations, manganese, cadmium, zinc and nickel has increased as a consequence, and large areas of forest soils now have acidity conditions such that any additional input of strong mineral acids causes a rapid increase in the release rates of these elements. Soil acidification and metal fluxes differ between tree species (spruce, beech and birch). The effect of soluble humic matter on metal solubility is discussed, as is the importance of metal speciation to the flux rates of elements in forest ecosystems. © 1990.