PARAMETERS OF SURFACE HETEROGENEITY FROM LABORATORY EXPERIMENTS ON SOIL DEGRADATION

In this study, we examined the applicability of the theory of gas adso rption on heterogeneous surfaces to assess changes in soil particle su rfaces in degrading soils. Soil degradation was simulated by laborator y treatments of gray forest soil (Udic Argiboroll), chernozem soil (Ty pic Haploboroll), and chestnut soil (Ustolic Orthid) samples. Water va por adsorption energy and to assess the strength of the surface attrac tive field. A modified Brunauer-Emmett-Teller equation provided a good fit of the water vapor adsorption isotherms on soil minerals for rela tive vapor pressures in the range of 0.05 to 0.85. This equation was u sed as a local isotherm equation. The piecewise distribution technique was applied to estimate the surface adsorption energy distribution. A fter a H2O2 treatment, the monolayer capacity and average adsorption e nergy decreased in the samples of all three soils. After cyclic wettin g-drying, the adsorption energy range decreased. After silica acid tre atments, the monolayer capacity decreased, and the energy distribution became much narrower. All treatments resulted in a loss of the low-en ergy adsorption sites and an increase in the number of layers retained by the surface at saturation vapor pressure. The exchangeable Ca cont ent changed after the treatments in the same way as the monolayer capa city did. The exchangeable Mg content increased after organic matter o xidation and slightly decreased after the silica treatments. The excha ngeable K content increased after both organic matter oxidation and th e wetting-drying treatments.