Nitrogen Stable Isotopes in Marine Environments

Yoshinari, T., and Koike, I. (1994). The use of stable isotopes for the studies of gaseous nitrogen species in the marine environment. In Stable isotopes in ecology and environmental science (Lajtha, K., Michener, R. H., eds.). BlackweU Scientific, Oxford, pp. 114-137. 

Kaplan 1. R. (1983) Stable isotopes of sulfur, nitrogen and deuterium in Recent marine environments. In Stable Isotopes in Sedimentary Geology, SEPM Short Course. Society for Sedimentary Research (SEPM), Tulsa, pp. 2-1-2-108. 

It has been a serious draw-back in studies of nitrogen transformations that a useful radioisotope of nitrogen does not exist. The isotope, N, is available only at accelerator facilities and has a half-life of 5 min, which strongly limits its applicability. Instead, the stable isotope, N, has been used successfully as a tracer in studies of nitrogen transformations in the marine environment. For example, the use of N03 by the isotope pairing technique has offered possibilities to study the process of denitrification of NOj" to (Nielsen 1992). The NO3" is added to the water phase over the sediment and is allowed to diffuse into the sediment and gradually equilibrate with NO3 in the pore water. By analyzing the isotopic composition of the formed N, i.e. 

Nitrogen has two stable isotopes, and (atomic masses of 14 and 15, respectively). is the more abundant of the two, comprising 99.63% of the nitrogen found in nature. Physical, chemical, and biological processes discriminate between the two isotopes, leading to subtle but measurable differences in the ratio of to among different forms of nitrogen found in the marine environment. 

Pathways of carbon flow in natural environments have also been reconstracted using bulk stable carbon and nitrogen isotopes as well as compound-specific isotopic analysis of individual biomarker lipid component (Hayes et al, 1990) based on the fractionations involved during primary (photosynthetic) and secondary (heterotrophic) processes. Recently, compound-specific radiocarbon analysis of individual biomarker hpid has been shown to be a valuable technique to determine the source of marine organic matter (Eglinton et al., 1997). 

Tittlemier SA, Fisk AT, Hobson KA, Norstrom RJ (2002) Examination of the Bioaccumulation of Halogenated Dimethyl Bipyrroles in an Arctic Marine Food Web Using Stable Nitrogen Isotope Analysis. Environ Pollut 116 85... 

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