Numerical modeling of heavy metal pollutant transport-transformation in fluvial rivers

Two-dimensional numerical modeling of chemical transport–transformation in fluvial rivers: formulation of equations and physical interpretation

“…Also another treatment in the model equation was that the instant equilibrium between particulate SAPs concentration and dissolved SAPs concentration was assumed. The invalidity of this assumption has been questioned by many researchers (Koelmans et al 2001;James 2002;Huang et al 2007b). …”

“…Thus, the equation describing transport-transformation of SAPs was a traditional convection -diffusion equation plus the "sedimentation -resuspension" term (terms representing degradation, photolysis, volatilization and hydrolysis were also included for the chemical fate model equation) (Mossman et al 1988). Detailed reviews can be found in the literature (Khondaker 2000;Koelmans et al 2001;James 2002;Huang et al 2007b). Also another treatment in the model equation was that the instant equilibrium between particulate SAPs concentration and dissolved SAPs concentration was assumed.…”

“…The water temperature, which can be taken as typical of sediment-motion-non-related pollutants, has little to do with sediment motion. Heavy metals (Huang et al 2007b), organic chemicals, especially hydrophobic organic compounds (HOCs) (Mossman et al 1988;Allen-King et al 2002;Kim et al 2004), nutrients such as salts of nitrogen and phosphorus (Koelmans et al 2001), certain bacteria (Mahler et al 2000) and various kinds of oils (Khondaker 2000) Huang et al (2007a,b,c), to cite just a few. Partly due to the sediment transport effect, partly due to data scarcity in validating the numerical model, in which flow, sediment transport and transporttransformation of SAPs in fluvial rivers were simultaneously considered, numerical modeling of SAPs transport-transformation in fluvial rivers has been a challenging subject (Ziegler et al 2000).…”

“…The significance of sediment transport on fate, transport -transformation of SAPs has been well recognized and documented; however, the effect of sediment transport was greatly simplified in these model equations. It was usually considered with a source/ sink term known as sedimentation -resuspension (Mossman et al 1988;Ji et al 2002;Kim et al 2004;Huang et al 2007b). Thus, the equation describing transport-transformation of SAPs was a traditional convection -diffusion equation plus the "sedimentation -resuspension" term (terms representing degradation, photolysis, volatilization and hydrolysis were also included for the chemical fate model equation) (Mossman et al 1988).…”

“…As sediment motion occurs ubiquitously in natural rivers, lakes and other surface water bodies, pollutants can be grouped into sediment-motion-related pollutants or (particulate-) sediment-associated pollutants (SAPs) and sediment-motion-non-related ones (Hart 1986;Huang 1993;Mahler et al 2000;Ellison & Brett 2006;Huang et al 2007b). The water temperature, which can be taken as typical of sediment-motion-non-related pollutants, has little to do with sediment motion.…”