% IMPORTANT: The following is UTF-8 encoded.  This means that in the presence
% of non-ASCII characters, it will not work with BibTeX 0.99 or older.
% Instead, you should use an up-to-date BibTeX implementation like “bibtex8” or
% “biber”.

@ARTICLE{Well:22329,
      author       = {Well, R. and Eschenbach, W. and Flessa, H. and von der
                      Heide, C. and Weymann, D.},
      title        = {{A}re dual isotope and isotopomer ratios of {N}2{O} useful
                      indicators for {N}2{O} turnover during denitrification in
                      nitrate-contaminated aquifers?},
      journal      = {Geochimica et cosmochimica acta},
      volume       = {90},
      issn         = {0016-7037},
      address      = {New York, NY [u.a.]},
      publisher    = {Elsevier},
      reportid     = {PreJuSER-22329},
      pages        = {265 - 282},
      year         = {2012},
      note         = {This study was supported by the Deutsche
                      Forschungsgemeinschaft (DFG), the Deutsche Bundestiftung
                      Umwelt (DBU) and the Oldenburgisch-Ostenfriesischer
                      Wasserverband (OOWV). We thank Ingrid Ostermeyer and Karin
                      Schmidt for technical assistance, Christian Ahl for
                      supplying laboratory facilities, Christian Gliesche for
                      information on the occurrence of fungi in groundwater and
                      the Centre for Stable Isotope Research and Analysis at the
                      University of Gottingen for isotope analysis. We gratefully
                      acknowledge the constructive comments and valuable
                      recommendations made by Nathaniel Ostrom and another two
                      anonymous reviewers on a former version of this paper.},
      abstract     = {Denitrifying aquifers are sources of the greenhouse gas
                      N2O. Isotopic signatures reflect processes of production and
                      reduction of N2O, but it is not clear to which extent these
                      can be used to quantify those processes. We investigated the
                      spatial distribution of isotopologue values of N2O (delta
                      O-18, average delta N-15, and N-15 site preference, SP) in
                      two denitrifying sandy aquifers to study N2O production and
                      reduction and associated isotope effects in groundwater. For
                      the first time, we combined this approach with direct
                      estimation of N2O reduction from excess-N-2 analysis.
                      Groundwater samples were collected from 15 monitoring wells
                      and four multilevel sampling wells and analysed for NO3-,
                      dissolved N2O, dissolved O-2, excess N-2 from
                      denitrification and isotopic signatures of NO3- and N2O.
                      Both aquifers exhibited high NO3- concentrations with
                      average concentrations of 22 and 15 mg N L-1, respectively.
                      Evidence of intense denitrification with associated N2O
                      formation was obtained from mean excess-N-2 of 3.5 and 4.3
                      mg N L-1, respectively. Isotopic signatures of N2O were
                      highly variable with ranges of 17.6-113.2 parts per thousand
                      (delta O-18), 55.4 to 89.4 parts per thousand (delta
                      N-15(bulk)) and 1.8-97.9 parts per thousand (SP). delta N-15
                      and delta O-18 of NO3- ranged from 2.1 parts per thousand to
                      65.5 parts per thousand and from -5 parts per thousand to
                      33.5 parts per thousand, respectively.The relationships
                      between delta N-15 of NO3- , delta N-15(bulk) and SP were
                      not in good agreement with the distribution predicted by a
                      Rayleigh-model of isotope fractionation. The large ranges of
                      delta O-18 and SP of N2O as well as the close correlation
                      between these values could be explained by the fact that N2O
                      reduction to N-2 was strongly progressed but variable.We
                      confirm and explain that a large range in SP and delta O-18
                      is typical for N2O from denitrifying aquifers, showing that
                      this source signature can be distinguished from the isotopic
                      fingerprint of N2O emitted from soils without water-logging.
                      We conclude that isotopologue values of N2O in our sites
                      were not suitable to quantify production or reduction of N2O
                      or the contribution of different processes to the total N2O
                      flux, apparently because these values were not only governed
                      by individual pathways but eventually also by the spatial
                      distribution of substrates and activity within the aquifers.
                      These observations could be explained by the dynamics of N2O
                      production, reduction and transport in water-saturated
                      systems with heterogenic distribution of microbial activity
                      and by a combination of diffusive and enzymatic isotope
                      effects. (C) 2012 Elsevier Ltd. All rights reserved.},
      keywords     = {J (WoSType)},
      cin          = {IBG-3},
      ddc          = {550},
      cid          = {I:(DE-Juel1)IBG-3-20101118},
      pnm          = {Terrestrische Umwelt},
      pid          = {G:(DE-Juel1)FUEK407},
      shelfmark    = {Geochemistry $\&$ Geophysics},
      typ          = {PUB:(DE-HGF)16},
      UT           = {WOS:000306334200016},
      doi          = {10.1016/j.gca.2012.04.045},
      url          = {https://juser.fz-juelich.de/record/22329},
}