Hydrosorption Properties of Natural and Technogenic Soils in an Experiment with Organic Matter Destruction

The contribution of organic matter content to the hydrosorption properties of soils is demonstrated. Hydrosorption properties were studied for soils of different genesis and with different degrees of technogenic load. Among technogenic soils, urban and arable soils are considered. Natural soils are represented by soddy eluvial metamorphic on varved clays (Albic Stagnic Retisol (Siltic)), gray metamorphic (Luvic Greyzemic Phaeozem (Clayic, Humic)) and clayey illuvial chernozem (Luvic Chernozem (Clayic, Humic)) on brown clays. Sorption isotherms constructed using the BET method and the specific surface areas of the initial samples and samples after organic matter destruction were compared. Organic matter was destroyed in a laboratory experiment using hydrogen peroxide. It has been revealed that treatment with H₂O₂ led to a significant decrease in the sorption capacity of soils and a change in hysteresis phenomena. At the same time, the sorption capacity of the soils decreased differently. The specific surface area decreased from 1.9 to 2.8 times. Statistical analysis has shown no correlation between the degree of reduction in specific surface area and the degree of reduction in organic matter content. However, a close correlation has been found between the degree of reduction in specific surface area and the initial organic matter content. The higher the initial organic matter content of the soil, the greater the reduction in specific surface area as a result of the treatment. It has been revealed that treatment with H₂O₂ has the most significant effect on equilibrium water contents in the capillary condensation interval. The sorption capacity of the urban soils was lower than that of their natural and arable counterparts. At a relatively high organic carbon content in urban soils, its destruction had a lower effect on the specific surface than that in other soils, which suggests that it is related to the qualitative composition of the organic matter.