Modeling Solute Transport in Volcanic Ash Soils with Cation Exchange and Anion Retardation

Summary, in English

Groundwater under agricultural lands is often contaminated by nitrate. In southern Japan, aquifers are covered by volcanic ash soils that can leach nitrate to the groundwater. In this study, column experiments using two volcanic ash soils (Kuroboku and Akahoya) were carried out. A mixed solution of KNO3 and K2SO4 was used in the leaching experiments. Based on the experiments, a reactive transport model was developed using the Constrained Interpolation Profile method for ion transport and used to calculate chemical equilibrium for the cation exchange reactions. Anion adsorption was modeled by retardation in the numerical model. The developed simulation model results were compared to results obtained by the reactive transport model PHAST. The developed model was shown to quite well reproduce general characteristics of the experimental results. Also, the developed model results agreed well with results from PHAST. Slight discrepancy between observed and calculated breakthrough curves was probably caused by ignoring the kinetic reaction in the model calculations.

• Author: Kei Nakagawa; Kazuro Momii; Ronny Berndtsson
• Department/s: Centre for Advanced Middle Eastern Studies (CMES); MECW: The Middle East in the Contemporary World; Division of Water Resources Engineering; LTH Profile Area: Water
• Publishing year: 2011
• Language: English
• Pages: 335-342
• Publication/Series: Environmental Modeling and Assessment
• Volume: 16
• Issue: 4
• Links: http://dx.doi.org/10.1007/s10666-011-9262-6
• Document type: Journal article
• Publisher: Springer
• Topic: Water Engineering
• Keywords: Volcanic ash soils; Nitrate; Cation exchange; Anion adsorption; Reactive transport
• Status: Published
• ISBN/ISSN/Other: ISSN: 1573-2967