Composition of stable carbon isotopes 13C/12C in soils of the Selenga highlands

The article presents the results of studying the composition of stable carbon isotopes 513C of organic matter and carbonates of soils of the Selenga Highlands. The 513C values of soils vary from -28.88 to -22.98%o, which indicates the formation of their organic matter when the C3 plant biomass enters. Fractionation of isotopes during the mineralization of organic matter leads to an increase in 513C values with the depth. At the same time, in soils formed under steppe landscapes, the increase in 513C is about 3%. In dry soils of the Selenga Highlands, a pronounced lightening of the composition of stable carbon isotopes of organic matter is observed.