Nonequilibrium sorption of organic chemicals by low organic-carbon aquifer materials

Brusseau, Mark L.; Reid, Mary Elizabeth

doi:10.1016/0045-6535(91)90322-5

Cited by 30 publications

(18 citation statements)

References 19 publications

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“…The third is a sandy aquifer material (Borden), collected near a sand quarry located at the Canadian Forces Base, Borden, Ontario. Breakthrough curves from displacement of PFBA through the Borden media were reported by Brusseau and Reid [1991]. Selected properties of these three sandy materials and of the attendant packed columns are provided in Table 1. The three media discussed above represent nonaggregated media, at least at the macroscopic level.…”

Section: A Lumped or "Apparent" Dispersivity (A•) Can Be Obtained By mentioning

confidence: 99%

The influence of solute size, pore water velocity, and intraparticle porosity on solute dispersion and transport in soil

Brusseau¹

1993

Water Resources Research

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108

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The purpose of this work was to investigate the effect of solute size, pore water velocity, and intraparticle porosity on dispersion and to delineate conditions under which it is appropriate to use a tracer-derived dispersivity to represent the dispersivity of other, dissimilar-sized solutes. This was accomplished by evaluating the physical properties of four porous media and the results of several column experiments performed with nonreactive tracers and these media. Intraparticle porosities of three sandy media were shown to constitute negligible fractions of the total porosities. As a result, intraparticle diffusion did not contribute to dispersive flux. The contribution of intraparticle diffusion, as well as film diffusion, to solute dispersion in fine-grained media having small intraparticle porosities will be negligible for most conditions. In addition, the importance of axial diffusion decreases as pore water velocity increases. Hydrodynamic dispersion is the predominant source of dispersion under these conditions, and, as such, dispersivity is essentially independent of solute size. Dispersivities determined with a tracer may therefore be used to represent the dispersivity of other, dissimilar-sized solutes. Under these conditions, the practice of using a nonreactive tracer such as 3H20 to characterize the dispersive properties of a soil column is valid. Solute dispersion in an aggregated soil was shown to be caused by a combination of hydrodynamic dispersion, film diffusion, and intraparticle diffusion. In addition, axial diffusion was shown to be important at low pore water velocities. Hence, the apparent dispersivities obtained by applying the single-component dispersion equation to transport in structured soils will generally be a function of solute size. The use of a tracer-derived dispersivity for solutes of different sizes would not be valid in this case. forming a set of miscible displacement experiments is as follows. First, tracer experiments are performed with one or more nonsorbing, nonreactive solutes such as 3H20 or chloride. The results obtained from the tracer experiments are then analyzed with the selected transport model, usually the well-known advective-dispersive equation. This analysis includes solving the inverse problem to obtain a value for the dispersion-related parameter. This value is thereafter used in the analysis of experimental results obtained for all other solutes with the same system. A major assumption inherent to the approach described above is that dispersive flux will be the same for all solutes, irrespective of solute characteristics such as size, shape, and chemical reactivity. A corollary to the assumption that dispersion is solute invariant is that hydrodynamic dispersion is the only mechanism contributing to dispersive flux. The assumption that hydrodynamic dispersion constitutes total dispersion measured in a column experiment is one of the most widely held tenets in the field of solute transport. Despite its widespread use, the validity of this assumptionhas be...

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Section: A Lumped or "Apparent" Dispersivity (A•) Can Be Obtained By mentioning

confidence: 99%

The influence of solute size, pore water velocity, and intraparticle porosity on solute dispersion and transport in soil

Brusseau¹

1993

Water Resources Research

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108

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“…The arrows show adsorption and desorption results in the same test tube. Reversibility in adsorption-desorption was obtained in column experiments with sandy loam (low clay mineral and organic contents) by Brusseau and Reid (1991). Brusseau and Rao (1989) explained that reversibility should be expected in such systems unless there is biological activity or some other degradation of the solute.…”

Section: Kmmentioning

confidence: 99%

“…Some investigators studying adsorption of different organic contaminants (polychlorinated biphenyls [PCBs], atrazine, polynuclear aromatic hydrocarbons [PAH]) working with sediments and organic-rich soil reported a strong hysteresis phenomenon (Bowman and Sans, 1985;Di-Toro and Horzempa, 1982;Isaacson and Frink, 1984;Miller and Weber, 1984;and Swanson and Dutt, 1973). Brusseau and Reid (1991), working with PAHs on sandy loam in column systems, reported a complete reversibility process with no hysteresis. Van Genuchten et al (1977) also indicated reversibility process on column experiments with 2,4,5-T on sandy loam soil.…”

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confidence: 97%

Adsorption–desorption of trichlorophenol in water–soil systems

Sabbah¹,

Rebhun²

1997

Water Environment Research

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Adsorption‐desorption of trichlorophenol (TCP) on calcium montmorillonite (pure clay), prepared montmorillonite‐humic complexes, and natural soils were investigated. Adsorption followed a Freundlich‐type isotherm between 5 and 30 mg/L of TCP, and linear adsorption isotherms were obtained for equilibrium concentrations up to 7 mg/L. Linear correlations were obtained between sorption constants (Kp) and organic carbon (foc) and clay‐mineral content (fm). In the montmorillonite and montmorillonite‐humic complex systems, adsorption and desorption isotherms coincided and no hysteresis was observed. Strong hysteresis was observed in adsorption‐desorption in natural soils. The different behavior in adsorption‐desorption was explained by the different nature of organic matter, its different structure, and interaction with the mineral fraction. Because trichlorophenol is a weak acid, adsorption highly depended on pH and could be predicted by combining the adsorption constant of undissociated TCP and the dissociation constant of phenol‐phenolate.

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“…Breakthrough curves obtained from experiments that employed a physical model of a stratified aquifer (a sand layer placed between two silt layers [Sudicky eta!., 1985]) were simulated we!! by both diffusion-based [Gillham eta!., 1984] and first-order-based [Brusseau, 1991] two-domain models. A first-order two-domain model was used successfully to simulate breakthrough curves obtained from the transport of a nonsorbing tracer in a physical model of a heterogeneous aquifer [Herr et al,!989].…”

Section: Conceptual Frameworkmentioning

confidence: 99%

Transport of rate‐limited sorbing solutes in heterogeneous porous media: Application of a one‐dimensional multifactor nonideality model to field data

Brusseau¹

1992

Water Resources Research

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The results of several experiments reported in the literature indicate that the assumptions of porous media homogeneity and instantaneous sorption are generally invalid for transport of sorbing solute at the field scale. In addition, it is probable that the "nonideal" transport observed is caused by more than one factor. The purpose of this work was to evaluate the ability of a one-dimensional, multifactor nonideality model to represent the nonideal transport of sorbing solutes at the field scale. For this model the two-domain approach is used to represent heterogeneity, and sorption is represented as being essentially instantaneous for a portion of the sorbent and rate limited for the remainder. Data (breakthrough curves) obtained from four field experiments reported in the literature were used to test the performance of the model. With one exception, data from laboratory or field experiments were used to identify values for input parameters; the exception concerned an assumption of a uniform distribution of sorbent between the advective and nonadvective pore water domains. Specification of input parameters independent of the data being simulated allowed the model to be used in a predictive mode. On the basis of the good match between predictions produced with the model and the data, it appears that the model provides a valid representation of sorption dynamics and solute transport for field-scale systems influenced by heterogeneity and rate-limited sorption. The model should be useful in situations where the extensive input data required for more complex models (e.g., stochastic) are not available.for the tracers and the organic solutes, obtained at a monitoring well, exhibited tailing. An extensive field experiment designed to investigate solute transport in a sand aquifer under natural gradient conditions was undertaken by personnel from Stanford University and the University of Waterloo [Mackay et al., !986a; Freyberg, 1986; Curtis et al., 1986; Roberts et al., !986; Sudicky, 1986]. Significant nonideal transport was observed for the organic solutes, wherein the plumes decelerated with time. This temporal increase in retardation Paper number 92WR00907. 0043-1397/92/92WR-00907 $05.00 factors was postulated to result from rate-limited sorption, involving diffusion within microporous particles [Curtis et al., !986; Roberts et al., 1986]. The sorptive behavior of several organic solutes under induced-gradient conditions was evaluated in an experiment that was performed to assess the efficacy of flushing as a means to remediate a contaminated aquifer [Whiffen and Bahr, !984]. Contaminant profiles obtained from the experiment, which was performed using an injection-extraction well couplet, exhibited extended tails. This nonideal behavior was attributed to rate-limited desorption. The results of a series of induced gradient experiments performed as part of an effort to evaluate in situ biorestoration were recently reported [Roberts and Semprini, 1989]. Breakthrough curves for the organic solutes exhibited tailing, ...

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Nonequilibrium sorption of organic chemicals by low organic-carbon aquifer materials

Cited by 30 publications

References 19 publications

The influence of solute size, pore water velocity, and intraparticle porosity on solute dispersion and transport in soil

The influence of solute size, pore water velocity, and intraparticle porosity on solute dispersion and transport in soil

Adsorption–desorption of trichlorophenol in water–soil systems

Transport of rate‐limited sorbing solutes in heterogeneous porous media: Application of a one‐dimensional multifactor nonideality model to field data

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