Fig. 9. Mineralization of Al–organic matter precipitates (Al/C ratio 0.1) produced from dissolved organic matter solutions from the Oa and Oi horizons of a beech and a spruce forest at pH 3.8 and 4.5 (incubation at pH 4.5 and 20°C for 7 wk). Mean values and standard error of three replicates.