Geochemical aspects of aluminium in forest soils in Galicia (N.W. Spain)

The aqueous speciation of Al was studied in acid forest soils in N.W. Spain. Aluminum concentrations were 10–70 mol L^–1, with variable proportions oflabile, nonlabile, andacid-soluble Al. Almost all thelabile Al was found complexed with F^–, Al³⁺ concentrations being low. The importance of organic matter was seen in the formation of Al-organic complexes in the solid soil fraction and the presence of aqueous alumino-organic complexes in superficial horizons (umbric epipedons) rich in organic matter.