Organic Carbon Metabolisms are Main Determinants of Hydrogen Demand and Dynamics in Anaerobic Soils

Hydrogen (H2) is a crucial electron donor for many processes in the environment including nitrate-, sulfate- and, iron-reduction, homoacetogenesis, and methanogenesis, and is a major determinant of microbial metabolic pathways and competition in groundwater and soils. Despite the importance of H2 for many microbial processes in the environment, the total H2 consuming capacity of soils is unknown. Using soil microcosms with added H2, the aim of this study was to 1) measure H2 demand or accepting capacity in geochemically diverse soils, and 2) define the processes responsible for this H2 demand.