Fig. 2. Results from the sequential extraction of acidic soils (A, C) and neutral soils (B, D). Absolute amounts are shown in the upper panels (A, B) and relative amounts (normalized by the sum of extracted Zn) in the lower panels (C, D). Soils are arranged by increasing total Zn content (X-ray fluorescence analyses) from left to right. The hypothetical interpretation of the sequential extraction is provided in Table 1.