Nitrogen isotopes in the ocean

D. M. Sigman, F. Fripiat

Research output: Chapter in Book/Report/Conference proceedingChapter

65 Scopus citations


This article outlines the isotope systematics of processes in the ocean nitrogen (N) cycle and their impact on the isotopic compositions of the major N forms, with an eye toward how the N isotopes may record current N fluxes and past changes. The dominant dynamic is of kinetic isotope discrimination, in which the light isotope of N (14N) is preferentially converted from substrate to product, leaving the substrate enriched in 15N. The strength of the isotopic signal increases with the amplitude of the isotope discrimination in a given N conversion, and it is also affected by the degree to which that conversion consumes its substrate, with a higher degree of consumption strengthening the signal in the substrate but weakening it in the product.

Original languageEnglish (US)
Title of host publicationEncyclopedia of Ocean Sciences
Number of pages16
ISBN (Electronic)9780128130810
ISBN (Print)9780128130827
StatePublished - Jan 1 2019

All Science Journal Classification (ASJC) codes

  • General Earth and Planetary Sciences


  • Ammonium
  • Assimilation
  • Denitrification
  • Dissolved organic nitrogen
  • Fixed nitrogen
  • Isotope fractionation
  • Nitrate
  • Nitrification
  • Nitrogen budget
  • Nitrogen fixation
  • Nutrient
  • Particulate nitrogen
  • Phytoplankton
  • Sediment


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