Formation rate of nonexchangeable organically bound tritium from tritiated soil water

The role of soil microorganisms in the formation of nonexchangeable organically bound tritium (OBT) from tritiated water (HTO) is investigated. Incubation experiments were conducted with five different soils. They were found to build up OBT at a rate of 0.03-0.05% per week. Addition of a substrate stimulated the formation of OBT up to 0.35% per week. Considering a loss of HTO from the soil by remission, only a negligible fraction of tritium is introduced into the terrestrial food chain.