Molecular-mass distribution of humin substances of soils of Western Transbaikalia

In meadow-chernozem permafrost and chestnut soils of Transbaikalia, differences in the structure of humic substances were found using the gel chromatography method. It was found that humic acids include fractions with molecular weights: >100, 50-70, and 5-15 kDa, respectively, whereas fulvic acids - one fraction (1.5-4.4 kDa). This ratio of fractions in the structure of humic substances of soils of different origin determines the nature of the entry of organic matter into the soil and local conditions in the zone of humus formation. In oxidizing conditions the processes of chemical and microbiological mineralization prevail; in anaerobic, - along with a slowed-down mineralization of organic matter, its conservation and, possibly, a relative accumulation of microbiologically resistant components to further transformation take place.