13CO2/12CO2 pedosfery

Abstract

13CO2/12CO2 IN PEDOSPHERE Summary The 13CO2/12CO2 ratio in pedosphere varies up to 20‰ and mainly depends on the 13C/ 12C ratio of plants and soil organic matter, on soil respiration rate, and on transport processes of CO2. This is connected with the type of soil, its moisture, temperature and organic material content. Carbon dioxide is enriched with the isotope 13C in relation to plant tissues and soil organic matter from 1 to 9‰. In profile the greatest change of δ13C value occurs in the surface soil layer about 10 cm thick and exceeds 10‰ in relation to the atmospheric CO2. Deeper down to 1 m the changes do not exceed 1-3‰, and at depths of a few meters the gradient of 13C/12C ratio is not observed. Seasonal variations affected by changes in temperature and biosphere activity bring about the decrease of δ13C in spring and summer in temperate climate by about 4-5‰ and the 13C/12C ratio is negatively correlated with CO2 concentration in soil air.