Modeling of NOM-Facilitated PAH Transport through Low- <i>f _oc</i> Sediment

Abstract

A finite-difference model was developed to more closely examine the observation that polycyclic aromatic hydrocarbon (PAH) transfer to and from low-organic-carbon aquifer sediment and aqueous natural organic matter (NOM) apparently occurred uninhibited by kinetic limitations during facilitated-transport and enhanced-desorption experiments performed in laboratory columns. The model accounted for advection, dispersion, and mass transfer between the various phases comprising the system; i.e., distribution of PAH between water and sediment and water and NOM, and distribution of NOM between water and sediment. The model was run using mass-transfer coefficients based on the equilibrium constants derived from experimental data and compared against the literature. Successful reproduction of the experimentally observed facilitated-transport and enhanced-desorption curves indicated that our physical system was free of kinetic limitations and was describable by the equilibrium constants comprising the system.