MODELING OF NOM-FACILITATED PAH TRANSPORT THROUGH LOW-F(OC) SEDIMENT

A finite-difference model was developed to more closely examine the ob servation that polycyclic aromatic hydrocarbon (PAH) transfer to and f rom low-organic-carbon aquifer sediment and aqueous natural organic ma tter (NOM) apparently occurred uninhibited by kinetic limitations duri ng 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 d erived from experimental data and compared against the literature. Suc cessful reproduction of the experimentally observed facilitated-transp ort and enhanced-desorption curves indicated that our physical system was free of kinetic limitations and was describable by the equilibrium constants comprising the system.