Nitrogen Isotopes in the Ocean

Publication Year


This article outlines the isotope systematics of the major processes in the ocean nitrogen (N) cycle, their impact on the isotopic compositions of the major N reservoirs in the ocean, and how the N isotopes in the modern ocean and sedimentary record 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 relatively enriched in 15N. The description of models and of observed N fluxes and pools in the ocean is dominated by two general parameters: (1) the amplitude of the isotope discrimination in a given N conversion, and (2) the degree to which that conversion consumes its substrate. © 2009 Copyright © 2009 Elsevier Ltd. All rights reserved.
Series Title
Encyclopedia of Ocean Sciences
Elsevier Ltd