Natural Transport of Volatile Organic Compounds Due to Annual Variation of Soil Temperature

A theoretical investigation of factors affecting gas phase transport of volatile organic compounds in unsaturated zone is presented. Studying annual soil temperature variation with time and depth declares that there is a considerable temperature variation in the upper few meters that may affect the overall natural mass transport of volatile organic compounds. A one-dimensional mathematical model is used to study the effect of soil temperature variation on diffusive mass transport. From the analytical solution, it is clear that there is a significant net mass transport upward direction and a stimulated spatial oscillation of contaminant concentration in soil. The magnitude of these two modes of mass transport is higher as the contaminant is more volatile.