Migration and sorption of jet fuel aliphatic vapors in unsaturated soil

Multicomponent vapor transport experiments were conducted in large (10.5 cm × 100 cm) columns packed with dry sand and wet soil to evaluate the effect of vapor phase sorption on the migration of jet fuel aliphatic components. A modified diffusion model accounting for sorption at the gas-soil and water-soil interface and vapor partitioning into the soil moisture was fitted to the experimental data of some aliphatic vapors and appeared to adequately describe their behavior. The best fi: results were used to determine an overall diffusion coefficient, D, which combines the effect of diffusion and sorption for each vapor. The two processes were isolated using the soil tortuosity, determined by model fitting of the experimental data of n-butane (used as a conservative gas tracer). Retardation factor, R, and overall linear sorption coefficients, K obs, computed from the respective D values, increased with decreasing water solubility of the aliphatic vapor for the same soil. Separation between sorption at the gas-soil and water-soil interface was possible only for wet soil but not for dry sand with the available experimental data.