Distribution of Gaseous 12 CO 2 , 13 CO 2 , and 14 CO 2 in the Sub-Soil Unsaturated Zone of the Western US Great Plains

Abstract

100% modern) 14 C activities are not observed in the deep unsaturated zone, in contrast to diffusion model predictions. 4) In spite of generally decreasing 14 C activities with depth, absolute partial pressures of 14 CO 2 in the subsoil unsaturated zone are 1–2 orders of magnitude higher than the partial pressure of 14 CO 2 in the atmosphere.