Measuring 15N-NH4/+ in marine, estuarine and fresh waters: An adaptation of the ammonia diffusion method for samples with low ammonium concentrations

R. M. Holmes, J. W. McClelland, D. M. Sigman, B. Fry, B. J. Peterson

Research output: Contribution to journalArticle

271 Scopus citations

Abstract

We present a method for measuring 15N-NH4+ in marine, estuarine and fresh waters. The advantage of this method is that it is broadly applicable to all types of water and it allows measurements in samples with lower ammonium concentrations than has previously been possible. The procedure is a modification of the ammonia diffusion method and uses large sample volumes (often 4 1) to obtain sufficient N for isotope ratio mass spectrometric analysis. Large volume samples have not previously been used with the diffusion procedure because isotopic fractionation occurs due to incomplete recovery of ammonium. However, the method we present accounts for this fractionation and allows precise correction of measured δ15N values.

Original languageEnglish (US)
Pages (from-to)235-243
Number of pages9
JournalMarine Chemistry
Volume60
Issue number3-4
DOIs
StatePublished - Apr 1 1998
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Oceanography
  • Chemistry(all)
  • Environmental Chemistry
  • Water Science and Technology

Keywords

  • Ammonia
  • Analytical methods
  • Diffusion
  • Fresh water
  • N-15
  • Sea water

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