Abstract

The theory for modeling non-equilibrium solute transport in porous media is still based on approximations to amodel proposed by Lapidus and Amundson in 1952 that has not been updated. This Mobile-Immobile Model(MIM) is based on the definition of a mass-transfer coefficient (?), which has been proven subject to some severelimitations. Measurements at both laboratory and field scales have demonstrated the scale-dependency of ?values. This means that the MIM theory fails in real applications, since ? is not constant, as defined in the kineticmodel theory, but is a time-residence (or distance) dependent coefficient. Multi-rate mass-transfer models havebeen proposed in recent literature to capture real-world solute transport with a multiple mass transfer. In thisstudy, we propose a novel model, which implements the analytical solution of Fick's second law of diffusiondirectly in the nonequilibrium advection/dispersion equation of solute transport in porous media. New modelsolutions properly fitted data collected during tracer tests carried out at the CNR-IRSA Laboratory (Bari, Italy) ina horizontal sandbox, 2m of length, by using sodium chloride as the conservative tracer. Selected breakthroughcurves at specific positions were used to validate the proposed model solution and estimate both conventionaland proposed coefficients of mass transfer. Results have shown a decreasing trend of ? from 0.09 to 0.04 h-1after about 1.2m of filtration for the investigated sand, whereas new solutions provide two scale-invariant tracercoefficients of rate of tracer mass-transfer (0.004 ± 0.005 h-1) and of tracer time delay (1.19 ± 0.01). Theproposed model performs very well, since it provides a readily solved analytical solution with respect to theconventional MIM. Results of the proposed MIM are very similar to those provided by the conventional MIM. Thenew model solution can be implemented in particle tracking or random walk software in order to solve twodimensionalnonequilibrium solute transport in groundwater.

Autore Pugliese

• Masciopinto Costantino , Passarella Giuseppe

Tutti gli autori

• C. Masciopinto; G. Passarella

Titolo volume/Rivista

Journal of contaminant hydrology

Anno di pubblicazione

2018

ISSN

0169-7722

ISBN

Non Disponibile

Numero di citazioni Wos

Nessuna citazione

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Numero di citazioni Scopus

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Ultimo Aggiornamento Citazioni

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Settori ERC

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Codici ASJC

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