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@PHDTHESIS{Burkhardt:30845,
      author       = {Burkhardt, Michael},
      title        = {{F}eldversuche zur {E}rfassung des {T}ransportverhaltens
                      von gelösten und partikulären {T}racern mittels
                      {M}ultitracing-{T}echnik in einem schluffigen {B}oden},
      volume       = {4058},
      issn         = {0944-2952},
      school       = {Univ. Bonn},
      type         = {Dr. (Univ.)},
      address      = {Jülich},
      publisher    = {Forschungszentrum Jülich GmbH Zentralbibliothek, Verlag},
      reportid     = {PreJuSER-30845, Juel-4058},
      series       = {Berichte des Forschungszentrums Jülich},
      pages        = {XIII, 192 p.},
      year         = {2003},
      note         = {Record converted from VDB: 12.11.2012; Bonn, Univ., Diss.,
                      2003},
      abstract     = {The spatial variability of physical properties in
                      structured soils and the precipitation rate are two
                      important factors that determine the transport behaviour of
                      dissolved and particulate substances through the vadose zone
                      into ground and surface waters. A multitracing-technique was
                      used to identify and characterize the transport phenomena
                      using the herbicide isoproturon, the conservative tracer
                      bromide (Br), the dye tracer Brilliant Blue (BB) and
                      fluorescent microspheres (MS) with 1 and 10 μm diameter.
                      Eight irrigation experiments on plots with an area of 2
                      m$^{2}$ were performed in a silty soil under different
                      tillage and irrigation conditions. MS were used for the
                      first time on field scale to mimic particulate transport.
                      Four plots were excavated directly after irrigation whilst
                      the other four were excavated after an exposure of 90 days
                      to the weather conditions, which were constantly monitored.
                      For each plot, horizontal cross-sections were photographed
                      at intervals between 5 to 10 cm for digital imaging
                      analysis. Disturbed soil samples were taken from all
                      cross-sections to analyse the applied substances and the
                      chemical soil properties. Br and isoproturon concentrations
                      were determined on 15 samples, whereas MS were determined on
                      50 samples. Furthermore, undisturbed soil cores were used to
                      determine the physical properties. The quantification of the
                      MS was done by fluorescence microscopy and digital imaging.
                      The BB concentrations were determined photometrically and
                      then related to the colour spectra of the digitised
                      photographs using two second-order, polynomial regression
                      functions. These functions were successfully transferred to
                      all plots to get spatially highly resolved concentration
                      patterns of each horizontal cross-section. The
                      representativeness of the sampling strategy based on 15
                      samples was confirmed by similar recoveries of the dye
                      tracer on 1 m$^{2}$. The transport behaviour of the applied
                      substances were compared by quantifying depth distributions
                      and spatial moment analysis. The results showed that the
                      depth of tillage directly influenced the mean transport
                      distance and the occurrence of preferential flow: deeper
                      tilled soils showed a larger mean transport distance of the
                      tracers and preferential flow was reduced. The dye coverage
                      and the depth distributions indicated that all substances
                      were transported preferentially up to 120 cm depth if an
                      irrigation rate of at least 6.7 mm h$^{-1}$ followed
                      directly after application. All results for the dissolved
                      and particulate tracers showed, that small quantities of
                      these substances are transported preferentially irrespective
                      of their physico-chemical properties. However, the mean
                      transport distance through the soil matrix is influenced by
                      these properties. The mean effective retardation of BB was
                      about 2 and 4 on the plots excavated 1 day and 90 days,
                      respectively, that of the MS between 1 and 7. A constant
                      ratio of approximately 0.2 was found between the mean
                      transport distance of Br and the maximum distance. The
                      convection-dispersion-equation (CDE) was able to describe
                      the bulk transport of Br with depth. The CDE could not
                      account for the tailing part of the depth distribution
                      probably caused by preferential flow. A possible explanation
                      for the occurrence of preferential flow is that the higher
                      irrigation and precipitation intensity destroy aggregates at
                      the soil surface and water ponded at the surface. This
                      results in a heterogeneous infiltration, although the
                      infiltration capacity of the matrix is not exceeded. The
                      highest concentrations of MS were always determined on these
                      consolidated soil surfaces. The precipitation rates had no
                      influence on the number of preferential flow pathways
                      created, however it directly influenced the transport
                      distance within the existing pathways and the mean transport
                      distance. Dye distribution and zones with local saturation
                      indicated that the plough layer is an important zone, which
                      may induce preferential flow.},
      cin          = {ICG-IV},
      cid          = {I:(DE-Juel1)VDB50},
      pnm          = {Chemie und Dynamik der Geo-Biosphäre},
      pid          = {G:(DE-Juel1)FUEK257},
      typ          = {PUB:(DE-HGF)11 / PUB:(DE-HGF)3},
      url          = {https://juser.fz-juelich.de/record/30845},
}