Fig. 3. The Al/C ratios in precipitates (solid phase) of the dissolved organic matter (DOM) solutions from the Oa and Oi horizons of a beech and a spruce forest in relation to the initially adjusted Al/C ratios in the DOM solutions. Precipitation was initiated at two different pH values: pH 3.8 (left) and pH 4.5 (right). Mean values and standard error of three replicates.