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δ15N

In geochemistry, hydrology, paleoclimatology and paleoceanography, δ15N (pronounced "delta fifteen n") or delta-N-15 is a measure of the ratio of the two stable isotopes of nitrogen, 15N:14N.[1]

Formulas edit

Two very similar expressions for δ15N are in wide use in hydrology.[2] Both have the form   ‰ (‰ = permil or parts per thousand) where s and a are the relative abundances of 15N in respectively the sample and the atmosphere. The difference is whether the relative abundance is with respect to all the nitrogen, i.e. 14N plus 15N, or just to 14N. Since the atmosphere is 99.6337% 14N and 0.3663% 15N, a is 0.003663 in the former case and 0.003663/0.996337 = 0.003676 in the latter. However s varies similarly; for example if in the sample 15N is 0.385% and 14N is 99.615%, s is 0.003850 in the former case and 0.00385/0.99615 = 0.003865 in the latter. The value of   is then 51.05‰ in the former case and 51.38‰ in the latter, an insignificant difference in practice given the typical range of -20 to 80 for δ15N.

Applications edit

The ratio of 15N to 14N is of relevance because in most biological contexts, 14N is preferentially uptaken as the lighter isotope. As a result, samples enriched in 15N can often be introduced through a non-biological context.

One use of 15N is as a tracer to determine the path taken by fertilizers applied to anything from pots to landscapes.[2] Fertilizer enriched in 15N to an extent significantly different from that prevailing in the soil (which may be different from the atmospheric standard a) is applied at a point and other points are then monitored for variations in δ15N.

Another application is the assessment of human waste water discharge into bodies of water.[3] The abundance of 15N is greater in human waste water than in natural water sources. Hence δ15N in benthic sediment gives an indication of the contribution of human waste to the total nitrogen in the sediment. Sediment cores analyzed for δ15N yield an historical record of such waste, with older samples at greater depths.

δ15N is also used to measure food chain length and the trophic level of a given organism; high δ15N values are positively correlated with higher trophic levels; likewise, organisms low on the food chain generally exhibit lower δ15N values. Higher δ15N values in apex predators generally indicate longer food chains.[4]

References edit

  1. ^ Katzenberg, MA (2008). "Chapter 13: Stable Isotope Analysis: A Tool for Studying Past Diet, Demography, and Life History". Biological Anthropology of the Human Skeleton (2nd ed.). Wiley. ISBN 978-0-471-79372-4.
  2. ^ a b Bedard-Haughn, A. (2003). "Tracing δ15N through landscapes: potential uses and precautions". Journal of Hydrology. 272 (1–4): 175–190. Bibcode:2003JHyd..272..175B. doi:10.1016/S0022-1694(02)00263-9.
  3. ^ "Sediment Delta 15N". 23 July 2010.
  4. ^ Perkins, Matthew J.; McDonald, Robbie A.; Van Veen, F. J. Frank; Kelly, Simon D.; Rees, Gareth; Bearhop, Stuart (27 March 2014). "Application of Nitrogen and Carbon Stable Isotopes (δ15N and δ13C) to Quantify Food Chain Length and Trophic Structure". PLOS One. 9 (3): e93281. Bibcode:2014PLoSO...993281P. doi:10.1371/journal.pone.0093281. PMC 3968125. PMID 24676331.

See also edit


δ15n, geochemistry, hydrology, paleoclimatology, paleoceanography, pronounced, delta, fifteen, delta, measure, ratio, stable, isotopes, nitrogen, contents, formulas, applications, references, alsoformulas, edittwo, very, similar, expressions, wide, hydrology, . In geochemistry hydrology paleoclimatology and paleoceanography d15N pronounced delta fifteen n or delta N 15 is a measure of the ratio of the two stable isotopes of nitrogen 15N 14N 1 Contents 1 Formulas 2 Applications 3 References 4 See alsoFormulas editTwo very similar expressions for d 15N are in wide use in hydrology 2 Both have the form 1000s aa displaystyle 1000 frac s a a nbsp permil or parts per thousand where s and a are the relative abundances of 15N in respectively the sample and the atmosphere The difference is whether the relative abundance is with respect to all the nitrogen i e 14N plus 15N or just to 14N Since the atmosphere is 99 6337 14N and 0 3663 15N a is 0 003663 in the former case and 0 003663 0 996337 0 003676 in the latter However s varies similarly for example if in the sample 15N is 0 385 and 14N is 99 615 s is 0 003850 in the former case and 0 00385 0 99615 0 003865 in the latter The value of 1000s aa displaystyle 1000 frac s a a nbsp is then 51 05 in the former case and 51 38 in the latter an insignificant difference in practice given the typical range of 20 to 80 for d 15N Applications editThe ratio of 15N to 14N is of relevance because in most biological contexts 14N is preferentially uptaken as the lighter isotope As a result samples enriched in 15N can often be introduced through a non biological context One use of 15N is as a tracer to determine the path taken by fertilizers applied to anything from pots to landscapes 2 Fertilizer enriched in 15N to an extent significantly different from that prevailing in the soil which may be different from the atmospheric standard a is applied at a point and other points are then monitored for variations in d 15N Another application is the assessment of human waste water discharge into bodies of water 3 The abundance of 15N is greater in human waste water than in natural water sources Hence d 15N in benthic sediment gives an indication of the contribution of human waste to the total nitrogen in the sediment Sediment cores analyzed for d 15N yield an historical record of such waste with older samples at greater depths d 15N is also used to measure food chain length and the trophic level of a given organism high d 15N values are positively correlated with higher trophic levels likewise organisms low on the food chain generally exhibit lower d 15N values Higher d 15N values in apex predators generally indicate longer food chains 4 References edit Katzenberg MA 2008 Chapter 13 Stable Isotope Analysis A Tool for Studying Past Diet Demography and Life History Biological Anthropology of the Human Skeleton 2nd ed Wiley ISBN 978 0 471 79372 4 a b Bedard Haughn A 2003 Tracing d 15N through landscapes potential uses and precautions Journal of Hydrology 272 1 4 175 190 Bibcode 2003JHyd 272 175B doi 10 1016 S0022 1694 02 00263 9 Sediment Delta 15N 23 July 2010 Perkins Matthew J McDonald Robbie A Van Veen F J Frank Kelly Simon D Rees Gareth Bearhop Stuart 27 March 2014 Application of Nitrogen and Carbon Stable Isotopes d15N and d13C to Quantify Food Chain Length and Trophic Structure PLOS One 9 3 e93281 Bibcode 2014PLoSO 993281P doi 10 1371 journal pone 0093281 PMC 3968125 PMID 24676331 See also editd 13C d 18O d 34S Isotopic signature Isotope analysis Isotope geochemistry nbsp This isotope related article is a stub You can help Wikipedia by expanding it vte nbsp This geochemistry article is a stub You can help Wikipedia by expanding it vte Retrieved from https en wikipedia org w index php title D15N amp oldid 1208350303, wikipedia, wiki, book, books, library,

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