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@ARTICLE{Blossfeld:8251,
      author       = {Blossfeld, S. and Gansert, D. and Thiele, B. and Kuhn, A.
                      J. and Lösch, R.},
      title        = {{T}he dynamics of oxygen concentration, p{H} value, and
                      organic acids in the rhizosphere of {J}uncus spp.},
      journal      = {Soil biology $\&$ biochemistry},
      volume       = {43},
      issn         = {0038-0717},
      address      = {Amsterdam [u.a.]},
      publisher    = {Elsevier Science},
      reportid     = {PreJuSER-8251},
      pages        = {1186 - 1196},
      year         = {2011},
      note         = {Record converted from VDB: 12.11.2012},
      abstract     = {A novel type of planar optodes for simultaneous optical
                      analysis of pH and oxygen dynamics in the rhizosphere is
                      introduced. The combination of the optical, non-invasive
                      measurement of these parameters with sterile sampling of
                      rhizosphere solution across and along growing roots by use
                      of a novel type of rhizobox provides a methodical step
                      forward in the investigation of the physicochemical dynamics
                      of the rhizosphere and its underlying matter fluxes between
                      roots and soil. In this study, this rhizobox was used to
                      investigate the effect of oxygen releasing roots of three
                      Juncus species on the amount and distribution of organic
                      acids in reductive, oxygen-deficient soils of different pH
                      (pH 3.9-pH 5.9). Pronounced diurnal variations of oxygen
                      concentration and pH along the roots, particularly along the
                      elongation zone were observed. Long-term records over more
                      than eight weeks revealed considerable spatial and temporal
                      patterns of oxygen over a range of almost 200 mu mol O-2 L-1
                      and pH dynamics of +/- 1.4 pH units in the rhizosphere. A
                      strong effect of oxidative acidification due to oxygen
                      release by the plant roots was clearly visible for Juncus
                      effusus, whereas the roots of Juncus articulatus alkalinized
                      the rhizosphere. In contrast, roots of Juncus inflexus
                      induced no effects on rhizospheric pH. Only four different
                      organic acids (oxalate, acetate, formate and lactate) were
                      detectable in all soil solutions. Maximal concentration of
                      all organic acids occurred at pH 3.9, whereas the lowest
                      concentration of each organic acid was found at pH 5.9.
                      Hence, considering the pH-dependence of the redox potential,
                      the acid soil provided increased reductive conditions
                      leading to slower anaerobic degradation of organic acids to
                      CO2 or methane (CH4). The concentration of organic acids
                      decreased by up to $58\%$ within a distance of only 4 mm
                      from the bulk soil to the root surface, i.e. reciprocal to
                      the pronounced O-2-gradient. The decreasing presence of
                      organic acids toward the oxygen releasing roots is possibly
                      due to a change in the composition of the microbial
                      community from anaerobic to aerobic conditions. The present
                      study highlights the dynamic interplay between O-2
                      concentration, pH and organic acids as key parameters of the
                      physicochemical environment of the rhizosphere, particularly
                      for wetland plants growing in oxygen-deficient waterlogged
                      soils. (C) 2011 Elsevier Ltd. All rights reserved.},
      keywords     = {J (WoSType)},
      cin          = {ICG-3 / IBG-2},
      ddc          = {570},
      cid          = {I:(DE-Juel1)ICG-3-20090406 / I:(DE-Juel1)IBG-2-20101118},
      pnm          = {Terrestrische Umwelt},
      pid          = {G:(DE-Juel1)FUEK407},
      shelfmark    = {Soil Science},
      typ          = {PUB:(DE-HGF)16},
      UT           = {WOS:000290698100010},
      doi          = {10.1016/j.soilbio.2011.02.007},
      url          = {https://juser.fz-juelich.de/record/8251},
}