Water-soluble organic matter and soil solution acidity in the main soil types of the central forest state biosphere reserve

The dynamics of the soluble organic carbon (C-WSO) and pH in soil solutions of the main soil types of the Central Forest State Biosphere Reserve were described. Possible reasons for the pH variation were considered. It was found that different soils are characterized by specific levels of pH and C-WSO. The structure of the soil solution acidity and its changes with depth were analyzed, and the relationship between the acidity and the content of water-soluble organics substances (WSOs) was determined. The predominantly hydrophilic nature and polydispersity of WSOs in soil solutions were revealed, as well as a decrease in the proportion of high-molecular soil fractions with depth. It was found that the mobility of metals in soils depends on the amphiphilic properties of WSOs to which they are bound, the metal features, and the soil type. The possibility of selective absorption of metals bound to the hydrophobic WSO fraction was shown.