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 have been studied for soils of different genesis and degree of technogenic loading. Among the technogenic soils, urban and arable soils are considered. Natural soils are represented by Albic Stagnic Retisol (Siltic) on varved clays, Luvic Greyzemic Phaeozem (Clayic, Humic) and Luvic Chernozem (Clayic, Humic) on brown clays. The sorption isotherms constructed using the BET method and the specific surface areas of the initial samples and samples after organic matter destruction were compared. The destruction of organic matter was carried out in a laboratory experiment using hydrogen peroxide. It was found that treatment with H2O2 resulted in 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 in different ways. The specific surface area decreased from 1.9 to 2.8 times. Statistical analysis showed no correlation between the degree of reduction in specific surface area and the degree of reduction in organic matter content. However, a close correlation was 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. Treatment with H2O2 was found to have the most significant effect on equilibrium water contents during the capillary condensation interval. The sorption capacity of the urban soils was lower than that of their natural and arable counterparts. With a relatively high organic carbon content in the urban soils, the effect of its destruction on the specific surface was less than for the other soils, which allows us to consider it in relation to the qualitative composition of the organic matter.