Evidence of compound-dependent hydrodynamic and mechanical transverse dispersion by multitracer laboratory experiments
Chiogna G, Eberhardt C, Grathwohl P, Cirpka OA, Rolle M (2010)
Publication Type: Journal article
Publication year: 2010
Journal
Book Volume: 44
Pages Range: 688-693
Journal Issue: 2
DOI: 10.1021/es9023964
Abstract
Mass transfer, mixing, and therefore reaction rates during transport of solutes in porousmediastronglydependondispersion and diffusion. In particular, transverse mixing is a significant mechanismcontrolling natural attenuation of contaminant plumes in groundwater. The aim of the present study is to gain a deeper understanding of vertical transverse dispersive mixing of reaction partners in saturated porous media. Multitracer laboratory experiments in a quasi two-dimensional tank filled with glass beads were conducted and transverse dispersion coefficients were determined from high-resolution vertical concentration profiles. We investigated the behavior of conservative tracers (i.e., fluorescein, dissolved oxygen, and bromide), with different aqueous diffusion coefficients, in a range of grain-related Péclet numbers between 1 and 562. The experimental results do not agree with the classical linear parametric model of hydrodynamic dispersion, in which the transversecomponentisapproximatedasthesumofporediffusion and a compound-independent mechanical dispersion term. The outcome of the multitracer experiments clearly indicates a nonlinear relation between the dispersion coefficient and the average linear velocity. More importantly, we show that transverse mechanical dispersion depends on the diffusion coefficient of the compound, at least at the experimental benchscale. This result has to be considered in reactive-transport models, because the typical assumption that two reactants with different aqueous diffusive properties are characterized by the same dispersive behavior does not hold anymore. © 2010 American Chemical Society.
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Germany (DE)How to cite
APA:
Chiogna, G., Eberhardt, C., Grathwohl, P., Cirpka, O.A., & Rolle, M. (2010). Evidence of compound-dependent hydrodynamic and mechanical transverse dispersion by multitracer laboratory experiments. Environmental Science & Technology, 44(2), 688-693. https://doi.org/10.1021/es9023964
MLA:
Chiogna, Gabriele, et al. "Evidence of compound-dependent hydrodynamic and mechanical transverse dispersion by multitracer laboratory experiments." Environmental Science & Technology 44.2 (2010): 688-693.
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