Specificity of humic substances extracted from fissures and genetic horizons of peat-podzolic soil

A comparative characterization of humic acids (HAs) and fulvic acids (FAs) isolated from the material of fissures and genetic horizons of peat-podzolic soil is presented. It is shown that HAs from separate soil horizons differ sharply in their composition and properties, and the portion of hydrophilic fractions in their composition decreases with depth. This suggests the absence (or very slow) frontal migration of HAs in the soil profile. On the contrary, HAs isolated from the material filling the fissures are very homogeneous and resemble HAs isolated from the A1E horizon in their composition and properties. This confirms the probability of downward humus migration along the fissures from the upper soil horizons in the form of suspensions or colloidal solutions. An increase in the portion of hydrophilic HAs in the deep parts of fissure zones also supports this conclusion.