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A Model of Multicomponent Diffusion in a Reactive Acid Soil

Title data

Hauhs, Michael ; Hornung, U. ; Lange, Holger:
A Model of Multicomponent Diffusion in a Reactive Acid Soil.
In: Bourgeat, Alain P. (ed.): Proceedings of the Conference Mathematical Modelling of Flow Through Porous Media : St. Etienne, France, May 22 - 26, 1995. - Singapore : WorldScientific , 1995 . - pp. 231-247
ISBN 9810224834

Abstract in another language

In structured soils, a considerable amount of soil water can be immobile. As this immobile water is confined to the smallest pore classes, it may be nevertheless in contact with most of the reactive surface areas of the solid phase. A model is proposed for the following general case: i) The mobile soil water is characterized by a relatively low pH and high Al3+ concentrations due to internal or external inputs of acids; ii) the solid phase consists of silicate minerals (e.g. feldspars) that weather irreversibly and relatively independent of pH by releasing base cations, and iii) all soil water is exposed to a high partial pressure of CO2. In the simplest case we model this situation as a one-dimensional multicomponent diffusion problem in which the connections to the mobile phase and the solid phase are described by Dirichlet and Neumann boundary conditions, respectively. Precipitation of secondary minerals (Al(OH)3) in the water column is linked to decreased diffusion coefficients of dissolved ions. The resulting set of coupled non-linear partial differential equations has a nonstandard form, since a reaction-diffusion system is coupled to a condition of electric neutrality everywhere in space. Therefor, special care has to be taken when applying numerical techniques for parabolic systems. Test calculations show that the model exhibits a new mechanism for SO24 accumulation in acid soils that interferes in a nocel way with variations of NO3 in the mobile water.

Further data

Item Type: Article in a book
Refereed: No
Additional notes: BAYCEER6955
Institutions of the University: Faculties > Faculty of Biology, Chemistry and Earth Sciences > Department of Earth Sciences > Chair Ecological Modelling
Faculties > Faculty of Biology, Chemistry and Earth Sciences > Department of Earth Sciences > Chair Ecological Modelling > Chair Ecological Modelling - Univ.-Prof. Dr. Michael Hauhs
Research Institutions > Research Centres > Bayreuth Center of Ecology and Environmental Research- BayCEER
Faculties
Faculties > Faculty of Biology, Chemistry and Earth Sciences
Faculties > Faculty of Biology, Chemistry and Earth Sciences > Department of Earth Sciences
Research Institutions
Research Institutions > Research Centres
Result of work at the UBT: Yes
DDC Subjects: 500 Science
Date Deposited: 09 Oct 2015 05:57
Last Modified: 09 Oct 2015 05:57
URI: https://eref.uni-bayreuth.de/id/eprint/20323