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@ARTICLE{HaberPohlmeier:11685,
      author       = {Haber-Pohlmeier, S. and Bechtold, M. and Stapf, S. and
                      Pohlmeier, A.},
      title        = {{W}aterflow {M}onitored by {T}racer {T}ransport in
                      {N}atural {P}orous {M}edia {U}sing {M}agnetic resonance
                      {I}maging},
      journal      = {Vadose zone journal},
      volume       = {9},
      issn         = {1539-1663},
      address      = {Madison, Wis.},
      publisher    = {SSSA},
      reportid     = {PreJuSER-11685},
      pages        = {834 - 845},
      year         = {2010},
      note         = {We would like to thank the German Research Foundation (DFG)
                      for financial support (Sta 511/4-1, PO 746/2-1,
                      Transregional SFB TR32). We further thank Horst Hardelauf
                      for support when coupling the finite-volume flow model to
                      the PARTRACE code, and Ms. Wettengl and Ms. Lippert,
                      Forschungszentrum Julich, for the chemical analysis of Gd in
                      the used soil material.},
      abstract     = {Magnetic resonance imaging (MRI) was applied to the study
                      of flow processes in model and natural soil cores. Flow
                      velocities in soils are mostly too slow to be monitored
                      directly by MRI flow velocity imaging. Therefore, we used
                      for the first time diethylenetriaminepentaacetate in the
                      form Gd-DTPA(2-) as a tracer in spin echo multislice imaging
                      protocols with strong weighting of longitudinal relaxation
                      time T-1 for probing slow flow velocities in soils. Apart
                      from its chemical stability, the main advantage of
                      Gd-DTPA(2-) is the anionic net charge in neutral aqueous
                      solution. We showed that this property hinders adsorption at
                      soil mineral surfaces and therefore retardation. We found
                      that Gd-DTPA(2-) is a very convenient conservative tracer
                      for the investigation of flow processes in model and natural
                      soil cores. With respect to the flow processes in the
                      coaxial model soil column and the natural soil column, we
                      observed totally different flow patterns. In the first case,
                      the tracer plume moved quite homogeneously in the inner
                      highly conductive core only and the migration into the outer
                      fine material was very limited. A numerical forward
                      simulation based on independently obtained parameters showed
                      good agreement between experiment and simulation and thus
                      proves the convenience of Gd-DTPA as a tracer in MRI for
                      soil physical investigations. The natural soil core, in
                      contrast, showed a flow pattern characterized by
                      preferential paths, avoiding dense regions and preferring
                      loose structures. In the case of the simpler model column,
                      the local flow velocities were also calculated by applying a
                      peak tracking algorithm.},
      keywords     = {J (WoSType)},
      cin          = {ICG-4},
      ddc          = {550},
      cid          = {I:(DE-Juel1)VDB793},
      pnm          = {Terrestrische Umwelt},
      pid          = {G:(DE-Juel1)FUEK407},
      shelfmark    = {Environmental Sciences / Soil Science / Water Resources},
      typ          = {PUB:(DE-HGF)16},
      UT           = {WOS:000287739800004},
      doi          = {10.2136/vzj2009.0177},
      url          = {https://juser.fz-juelich.de/record/11685},
}