Physicochemical properties of the mineral horizons under the peat deposits in Western Siberia surface

Acidity and acid-base buffering of soils are largely products of soil formation and express the fundamental characteristics that control the mobility of chemical elements, including many nutrients and pollutants in soils and landscapes. In this connection it is necessary to explore the acid-base properties of different soil samples. This is especially significant for mineral horizons under the frozen marshes, since they may enter into the active layer of soil during warming, addressing barriers to migratory organic compounds in dissolved and colloidal form. The aim of this study was to examine acid-base status of mineral horizon sample surface occurring under the peat deposit in Western Siberia swamps. Samples were taken from the soil horizons, which are under the peat deposit, or may potentially be under it during waterlogging. The primary objective was to determine the basic chemical and physical-chemical parameters of horizons, which may affect their sorption activity with respect to the water-soluble organic substances. The importance of samples analyzing lies in the fact that the frozen north peat deposits will thaw until mineral horizons, with the inclusion of the latter in the active layer during global warming. Six soil horizon samples, chosen out of a peat deposit thawed and frozen bogs of Western Siberia, were studied. Determination of specific surface area and acid-base properties of the surface were carried out by the BET and pH meter methods respectively. Measurement of specific surface area and porosity of samples was performed using an automated sorption installation 3Flex produced by Micromeritics (USA) at a low-temperature nitrogen adsorption. It is shown that the investigated samples are quite different from the values of the specific surface area (from 0.2 to 65 m / g), which is the result of changes in their porosity - mesopo-rous (S sp = 65 m / g), large pore (S sp = 5 m / g) non-porous (S sp = 0,2 - 2,0 m / g), related to soil formation and the properties of the original parent rock. pH change of aqueous suspension was recorded every 5-'0 seconds since the establishment until the electrochemical adsorption equilibrium to characterize the acid-base properties of the surface soil samples. ITAN ionomer was used with the glass and silver chloride electrodes. It was determined that the nature of the acidity of the soil surface changes from acidic (pH_iis = 4) to almost neutral (pH_iis = 6.1). It was found that these differences should be reflected in the sorption capacity of mineral horizons, which underlie peat deposits, their capacity for sorption of organic substances _ from migrating radially soil solutions.

Keywords

Authors

References