Isotopic analysis of dissolved organic nitrogen in soils

G.H. Ros, E.J.M. Temminghoff, J.W. van Groenigen

Research output: Contribution to journalArticleAcademicpeer-review

8 Citations (Scopus)

Abstract

Determination of the isotopic signature of dissolved organic nitrogen (DON) is important to assess its dynamics in terrestrial ecosystems. Analysis of 15N-DON, however, has been hindered by the lack of simple, reliable, and established methods. We evaluate three off-line techniques for measuring the 15N signature of DON in the presence of inorganic N using a persulfate digestion followed by microdiffusion. The 15N-DON signature is calculated from the difference between total dissolved 15N (15N-TDN) and inorganic 15N. We quantified the 15N recovery and signature of DON, NH4+, and NO3- in a series of inorganic N/DON mixtures (with a TDN concentration of 10 mg N L-1) for three lab protocols. Phenylalanine was used as a model compound for DON. The best lab protocol determined the concentration of inorganic N and TDN prior to diffusion using improved spectrophotometric techniques. An accuracy of 88% for 15N-DON should be routinely possible; coefficient of variation was
Original languageEnglish
Pages (from-to)7814-7820
JournalAnalytical Chemistry
Volume82
Issue number18
DOIs
Publication statusPublished - 2010

Keywords

  • inorganic nitrogen
  • persulfate oxidation
  • microbial biomass
  • diffusion methods
  • n-15 analysis
  • amino-acids
  • mason jars
  • extracts
  • nitrate
  • water

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