TY  - JOUR
AU  - Jelinkova, V.
AU  - Snehota, M.
AU  - Pohlmeier, A.
AU  - Van Dusschoten, D.
AU  - Cislerova, M.
TI  - Effects of entrapped residual air bubbles on tracer transport in heterogeneous soil: Magnetic resonance imaging study
JO  - Organic geochemistry
VL  - 42
SN  - 0146-6380
CY  - Amsterdam [u.a.]
PB  - Elsevier Science
M1  - PreJuSER-17432
SP  - 991 - 998
PY  - 2011
N1  - The research was supported by the Czech Science Foundation Project No. 103/08/1552, by MZP CR SP/2E7/229/07 and by the Grant Agency of the Czech Technical University in Prague, Grant No. SGS10/146/OHK1/2T/11. We thank our colleague Martina Sobotkova from CTU in Prague, for her help with the experiments and two anonymous reviewers who contributed helpful comments to this work.
AB  - Magnetic resonance imaging (MRI) was used to study the process of infiltration and solute transport in an undisturbed soil sample of coarse sandy loam. The sample was subjected to the recurrent ponded infiltration (RPI) experiment, which was carried out in order to assess the changes in the entrapped air volume and its impact on steady state flow rates and solute breakthrough. The main stages of the first and second experimental RPI runs were monitored using an MRI sequence that follows both water density and magnetic relaxation. In a steady state stage of each experimental run a nickel nitrate pulse was injected in order to visualize the solute breakthrough. Effluent from the sample was collected for chemical analysis and a breakthrough curve of the nickel was constructed. To obtain information about the soil structure and to reveal potential preferential pathways, the soil sample was scanned using computed tomography. The local nickel ion transport breakthrough was evaluated from MR images in a series of local observation points distributed along the selected preferential pathways.The preferential flow instability phenomenon with the emphasis on air bubble formation was shown by detecting a 60% decrease of the steady state infiltration rate. The detailed analyses of MRI measurements at observation points revealed air bubble formation, producing a flow rate decrease accompanied by redirection of nickel ion transport trajectories. By analyzing M0 maps it was found that the volumetric water content decrease was 2.2%. (C) 2011 Elsevier Ltd. All rights reserved.
KW  - J (WoSType)
LB  - PUB:(DE-HGF)16
UR  - <Go to ISI:>//WOS:000295215300014
DO  - DOI:10.1016/j.orggeochem.2011.03.020
UR  - https://juser.fz-juelich.de/record/17432
ER  -