Aluminiumkonzentrationen und -bindungsformen von Bachwässern und wässrigen Bodenextrakten in den Hochlagen des Inneren Bayerischen Waldes

Aluminium concentrations and -species in streamwaters and water extracts at high elevations of the Inner Bavarian Forest During summer half-years 1986–1988 Al concentrations and Al species were recorded periodically for streamwaters of the Inner Bavarian Forest. Furthermore these analyses were carried out once with water extracts of 5 typical high elevation pedons. Total Al of streamwaters is strongly influenced by the hydrological situation. Highest Al concentrations (up to 1,5 mg/l Al) were found during subsurface flow (interflow) events, when inorganic Al species (Allabil) were predominant. In interflow and water extracts of high elevation sites the average molar ratio of Ca/Al_labil is ≧ 0,5 and the average Mg/Al_labil ratio ≧ 0,4. After Ulrich et al. (1984) and Jorns et al. (1985) these values are above the level of serious Al toxicity and thus they might not be the reason of the widespread Mg-deficiency in high elevation stands of Norway spruce. Water extracts of the examined soils have pK values similar to the mineral Jurbanit (AlOH₂SO₄). Thus in these soils a considerable part of Al should exist in this phase. The differing situation in interflow waters can be explained by an incomplete chemical equilibrium.