Soil & Water Res., 2010, 5(2):39-48 | DOI: 10.17221/4/2009-SWR

Tracer experiments within composite soil column investigated by MRIOriginal Paper

Vladimíra JELÍNKOVÁ^{1, 2}, Milena CÍSLEROVÁ¹, Andreas POHLMEIER², Dagmar van DUSSCHOTEN²

¹ Department of Irrigation, Drainage and Landscape Engineering, Faculty of Civil Engineering, Czech Technical University in Prague, Prague, Czech Republic

² Research centre Jülich, Institute of Chemistry and Dynamics of the Geosphere (ICG), Jülich, Germany

The magnetic resonance imaging (MRI) technique was used for the visualisation and interpretation of flow paths. A set of tracer-infiltration experiments was performed on soil columns filled with packed homogeneous sand and with a composite sand-soil system. The flow paths were visualised using a tracer-solution containing Ni(NO₃)₂ which is characterised by relaxation times different from that of the infiltrating water. The tracer pulse was added under hydraulic steady state conditions. Small disturbances in the tracer front were observed during the breakthrough in the case of a homogeneous sample. More pronounced effects were seen with the composite sample. The vertical components of the velocity fields were evaluated for the experiments presented. The irregularities in the tracer front and in the velocity fields were in this case attributed to the preferential flow phenomena in combination with air bubble entrapment. Beside that, two consecutive tracer pulses were performed with the aim of testing the potential influence of the different solute concentrations on the adsorption power. Both concentrations had negligible impacts on the acquired image. The presented results are constrained by the limits of the described technology; further investigations are being carried out using more advanced equipment. I

Keywords: Cambisol; infiltration; laboratory experiments; magnetic resonance imaging; porous medium; preferential flow; sand; soil samples; tracer; velocity field

Published: June 30, 2010  Show citation