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@PHDTHESIS{Wehrhan:51799,
      author       = {Wehrhan, Anne},
      title        = {{F}ate of veterinary pharmaceuticals in soil: {A}n
                      experimental and numerical study on the mobility, sorption
                      and transformation of sulfadiazine},
      volume       = {66},
      school       = {Universität Bonn},
      type         = {Dr. (Univ.)},
      address      = {Jülich},
      publisher    = {Forschungszentrum Jülich GmbH Zentralbibliothek, Verlag},
      reportid     = {PreJuSER-51799},
      isbn         = {3-89336-448-X},
      series       = {Schriften des Forschungszentrums Jülich. Reihe Umwelt /
                      Environment},
      pages        = {XXI, 134 S.},
      year         = {2006},
      note         = {Record converted from VDB: 12.11.2012; Universität Bonn,
                      Diss., 2006},
      abstract     = {Among other veterinary pharmaceuticals sulfadiazine (SDZ)
                      is a widely used antimicrobial substance in intensive
                      livestock production to prevent and treat diseases. Up to 40
                      $\%$ of the administered sulfonamides are eliminated as
                      microbial active substances with the excretions. Antibiotics
                      such as sulfadiazine reach agricultural soils directly
                      through grazing livestock or indirectly through the
                      spreading of manure or sewage sludge on the field. Knowledge
                      about the fate of antibiotics in soil is crucial to assess
                      the environmental risk of these compounds, including
                      possible transport to groundwater. Sorption, transport and
                      transformation of 4$^{14}$C-labelled SDZ in a silty loam
                      were investigated using batch-type and column experiments.
                      The batch sorption/ desorption experiments were conducted at
                      various concentration levels (0.044 to 13 mg L$^{−1}$
                      initial solute concentration) and time-scales (0.75 to 272
                      days). Sorption of SDZ in the investigated soil was
                      time-dependent and strongly non-linear with regard to the
                      concentration. The time to reach the apparent sorption
                      equilibrium was about 20 days. However, desorption was very
                      slow and 41 days were insufficient to reach the desorption
                      equilibrium. In annealed soil the sorption affinity was
                      lower and the desorption was also very slow. Transport of
                      $^{14}$C-labelled SDZ was investigated in disturbed soil
                      columns at a constant flow rate of 0.26 cm h$^{−1}$ near
                      saturation. $^{14}$C-SDZ was applied in different
                      concentrations (5.7 or 0.57 mg L$^{−1}$) for either a
                      short or a long pulse duration (7 or 70 hours). Breakthrough
                      curves (BTCs) of $^{14}$C-SDZ and the non-reactive tracer
                      chloride were measured. At the end of the leaching period
                      the soil concentration profiles were determined. The peak
                      maxima of the BTCs were delayed by a factor of 2 to 5
                      compared to chloride and the decreasing limbs are
                      characterized by an extended tailing. The maximum relative
                      concentrations differed as well as the eluted mass
                      fractions, ranging from 18 to 83 \% after 500 hours of
                      leaching. Mineralization of SDZ during the batch and column
                      experiments was neglectable. Inverse modelling techniques
                      were used to identify relevant sorption processes of SDZ and
                      its transformation products during the batch and column
                      experiments. One-, two- and three-domain sorption models
                      were tested, involving linear or non-linear, instantaneous
                      equilibrium, rate-limited reversible and irreversible
                      sorption. The various sorption concepts were included in a
                      convective–dispersive transport model for the description
                      of the column experiments. Models involving similar
                      processes and complexity were necessary to describe the
                      characteristic features of the batch and transport
                      experiments. The non-linear sorption in the batch
                      experiments was best described by the Freundlich sorption
                      isotherm and may also be one reason for the pronounced
                      tailing of the BTCs in the transport experiments.
                      Rate-limited sorption accounts for the slow attainment of
                      the apparent sorption equilibrium during the batch
                      experiments and can also contribute to the tailing of the
                      BTCs. However, sorption sites exhibiting instantaneous
                      equilibrium sorption were required in addition to the
                      kinetic sorption to describe both, the one-day adsorption
                      and the BTCs of the column transport experiments with the
                      long pulse duration. Only the consideration of irreversible
                      sorption enabled [...]},
      cin          = {ICG-IV},
      ddc          = {333.7},
      cid          = {I:(DE-Juel1)VDB50},
      pnm          = {Terrestrische Umwelt},
      pid          = {G:(DE-Juel1)FUEK407},
      typ          = {PUB:(DE-HGF)11 / PUB:(DE-HGF)3},
      url          = {https://juser.fz-juelich.de/record/51799},
}