Effect of molecular hydrogen on the reduction process of submerged soil

Abstract

When the paddy soil is submerged, several reduction reactions take place sequentially with the decrease in the release of free energy, as predicted by thermodynamic studies (9). Through this sequential reduction process the partial pressure of H2 in soil is generally kept low. However, when an air-dried soil rich in mineralizable organic matter is submerged, H2 evolution and its subsequent absorption occur within a few days after incubation (12). Furthermore, the reduced soil has the capacity to take up H2 (5). These facts suggest that H2 is transferred from one reduction process to another during the reduction process, because the observed H2 evolution results from the balance between H2 consumption and formation. In this report we describe the effect of H2-addition on the reduction process in the submerged soil.