Simple screening models of NAPL dissolution in the subsurface

• Published in: Journal of contaminant hydrology Vol. 72; no. 1; pp. 245 - 258
• Main Authors: Zhu, Jianting, Sykes, Jonathan F
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 01.08.2004; Elsevier Science
• Subjects: Breakthrough curves; Dissolution models; Earth sciences; Earth, ocean, space; Engineering and environment geology. Geothermics; Environmental Monitoring; Exact sciences and technology; Hydrogeology; Hydrology. Hydrogeology; Models, Theoretical; Nonaqueous phase liquids; Organic Chemicals - analysis; Pollution, environment geology; Porosity; Soil Pollutants - analysis; Solubility; Solute transport; Water Movements; Water Pollutants, Chemical - analysis; Solute transport; Breakthrough curves; Nonaqueous phase liquids; Dissolution models; Solubility; models; solutes; nonaqueous phase liquids; dissolution; ground water; effluents; concentration; digital simulation; transport; pollution; saturation; conservation; correlation; tailings; solubility; equilibrium; boundary conditions
• ISSN: 0169-7722; 1873-6009
• DOI: 10.1016/j.jconhyd.2003.11.002

Three simple screening models of nonaqueous phase liquid (NAPL) dissolution in the subsurface are proposed based on the NAPL mass conservation and the assumption of proportionality between the residual NAPL source zone concentration and the remaining residual NAPL mass. The purpose of the proposed models is to predict the solute concentration in the zone of the residual NAPL as a result of dissolution. The predicted source zone concentration decrease is used to simulate and account for the decrease of dissolution rate with time. The proposed simple NAPL dissolution models enable the pseudo-equilibrium formulation to be used and therefore the numerical simulations for field application problems can be simplified compared to the non-equilibrium counterpart. With proper choice of empirical parameters, the proposed simple screening models can work as well as more complex dissolution rate correlation models, such as that of Imhoff et al. [Water Resour. Res. 30 (1994) 307–320]. It is found that the proposed models are very good for quantifying non-equilibrium dissolution, which is characterized by tailing of breakthrough curves. The models are especially useful for situations of small residual NAPL saturation, which are typical for many field applications.