Ground‐Water Pollution by Transfer of Oil Hydrocarbons

Abstract

An important aspect of the pollution of a phreatic aquifer by hydrocarbons is the oil‐water contact and transfer of soluble substances from the oil into the ground water. A systematic study of this transfer of matter in a saturated porous medium (initial condition of contact when the impregnation body is submitted to fluctuations of the piezometric level) is performed with an experimental device made up of a porous matrix containing the oil phase, steady and crossed by a unidirectional flow of water. The transfer is very efficient; for all compounds which have been studied, the maximum possible concentration is reached after a distance of the order of 10 cm with specific flow rates greater than those generally encountered in a gravel‐sand aquifer. The selective impoverishment of the oil product with time, due to differences in the solubility of various hydrocarbons, modifies the dissolved phase composition. Downstream of an in‐situ impregnation body, this phenomenon only appears after a constant concentration has been reached for a long time. A source model is thus obtained, where the pollutant massic flow rate is proportional to the flow rate of the water which crosses the impregnation body. Such an initial condition has a fundamental effect on the determination of the contaminated aquifer domain, with the help of the dispersion scheme, with hydrocarbon concentrations evolving according to a general diffusion‐convection law.

Multiphase mass transport with partitioning and inter-phase transport in porous media

“…From a theoretical perspective, estimating these quantities is also possible using techniques, such as volume averaging (Whitaker, 1967(Whitaker, , 1977. The majority of previous theoretical works derive such models based on the assumption of mass exchange equilibrium between the aqueous and the non-aqueous liquid phases, as discussed at length in previous works (Hunt et al, 1988;Fried et al, 1979;Geller and Hunt, 1993;Lam et al, 1983). This assumption of infinitely fast diffusion in the non-aqueous phase, simplifies the mathematical modeling and the consequent simulation effort (Quintard and Whitaker, 1994;De Smedt and Wierenga, 1979;Gvirtzam et al, 1988).…”

Relationship between mass-flux reduction and source-zone mass removal: Analysis of field data

“…The fundamental concept of contaminant mass flux, its relationship to mass-removal processes and source-zone properties, and its impact on risk has long been established (e.g., Fried et al, 1979;Pfannkuch, 1984). The impact of subsurface heterogeneity, immiscibleliquid distribution, and mass-transfer dynamics on mass-removal behavior and aqueous concentration profiles (mass flux) has been examined for some time through laboratory, modeling, and field studies (e.g., Schwille, 1988;Dorgarten, 1989;Guiguer, 1991;Anderson et al, 1992; Brusseau, 1992;Guarnaccia and Pinder, 1992;Mayer and Miller, 1996;Berglund, 1997;Nelson and Brusseau, 1997;Powers et al, 1998;Unger et al, 1998;Broholm et al, 1999;Brusseau et al, 1999a;Frind et al, 1999;Zhang and Brusseau, 1999;Nambi and Powers, 2000;Zhu and Sykes, 2000;Brusseau et al, 2000Brusseau et al, , 2002 Saba and Illangasekare, 2000;Sale and McWhorter, 2001;Rivett et al, 2001;Enfield et al, 2002;Rao et al, 2002;Rao and Jawitz, 2003; Jayanti and Pope, 2004;Lemke et al, 2004;Parker and Park, 2004;Phelan et al, 2004;Soga et al, 2004; Falta et al, 2005a, b ;Jawitz et al, 2005; Feenstra, 2005, Fure et al, 2006;Lemke and Abriola, 2006;Suchomel and Pennell, 2006;Brusseau et al, 2007Brusseau et al, , 2008).…”

Mass transfer from nonaqueous phase organic liquids in water‐saturated porous media

“…Many multiphase transport models assume equilibrium partitioning among all fluid and solid phases [e.g., Pinder and Abriola, 1986;Corapciaglu and Baehr, 1987;Kaluarachchi and Parker, 1990]. The justification for assuming equilibrium has come from the column studies of the dissolution of homogeneously distributed organic liquid residuals [van der Waarden et al, 1971;Fried et al, 1979]. Observations at NAPL-contaminated sites of aqueous phase concentrations less than solubility have been attributed to the irregular distribution of the NAPL in the aquifer [Mackay et al, 1985;Wilson et al, 1990, Anderson et al, 1992a.…”