Fig. 4. Distribution of the zinc fractions in different soil profiles. Extractants: F-1, H₂O; F-2, 1 M NH₄OAc (pH 7.0); F-3, 1 M NH₄OAc (pH 5.0); F-4, 1 M NH₂OH.HCl in 25% HOAc; F-5, 30% H₂O₂ in HNO₃ (pH 2.0); F-6, aqua regia