Study of 13C/12C carbon isotopic composition in saline soils of the Selenga mid-mountain region

Using isotope mass spectrometry methods, we have studied the effect of glucose on microbial degradation of organic matter in saline soils of the Selenga mid-mountain region. Differences in the isotopic composition of glucose (513C -10,57%o) and organic matter (513C -26,55%) allowed us to calculate the fluxes of carbon dioxide (CO2) formed during their microbial degradation in soil. The highest amount of CO2 released was observed in the first 4 hours after application of glucose to the soil, which was 12 times higher than the rate of organic matter degradation before glucose application. The isotopic composition of CO2 with a value of -11.08% was observed at 8-hour incubation. In the experiment 513C CO2 inherits 513C of organic products used by microorganisms as substrates. The difference in the isotopic composition of exogenous glucose and organic matter contributed 513C can be used as an isotopic marker to determine the origin of CO2 produced during mineralization of plant residues.