Results 251 to 260 of about 34,135 (304)

Combined stomach content and stable isotope analyses revealed variations in trophic ecology of pacific cod in the east sea. [PDF]

Sci Rep
Kang MG, Majeed S, Jung HK, Lee CI, Park HJ, Park JW, Rho HS, Min WG, Park JM.   +8 more
europepmc   +1 more source

Reassessing the nitrogen isotope composition of sediments from the proto-North Atlantic during Oceanic Anoxic Event 2

, 2014
I. Ruvalcaba, Niels A. G. M. van Helmond, I. Tsandev, J.B.M. Middelburg, Caroline P. Slomp   +4 more
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Isotopic disproportionation during hydrogen isotopic analysis of nitrogen‐bearing organic compounds

Rapid Communications in Mass Spectrometry, 2015
Rationale High‐precision hydrogen isotope ratio analysis of nitrogen‐bearing organic materials using high‐temperature conversion (HTC) techniques has proven troublesome in the past. Formation of reaction products other than molecular hydrogen (H 2
Nair, S., Geilmann, H., Coplen, T., Qi, H., Gehre, M., Schimmelmann, A., Brand, W.   +6 more
openaire   +3 more sources

Isotopic Analysis of Dissolved Organic Nitrogen in Soils

Analytical Chemistry, 2010
Determination of the isotopic signature of dissolved organic nitrogen (DON) is important to assess its dynamics in terrestrial ecosystems. Analysis of (15)N-DON, however, has been hindered by the lack of simple, reliable, and established methods. We evaluate three off-line techniques for measuring the (15)N signature of DON in the presence of inorganic
Ros, G.H., Temminghoff, E.J.M., van Groenigen, J.W.   +2 more
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Nitrogen Isotope Tracing of Dissolved Inorganic Nitrogen Behaviour in Tidal Estuaries

Estuarine, Coastal and Shelf Science, 2001
Concentration versus salinity diagrams are the most widely used method to derive estuarine sources and sinks of nitrogen. This method can not distinguish conservative mixing due to a lack of activity, from that due to an approximate balance of sources and sinks.
Middelburg, J.J., Nieuwenhuize, J.
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Nitrogen isotopic composition of CK chondrites

Meteoritics, 1995
Abstract— Nitrogen abundances and isotopic compositions of four CK chondrites (ALH85002, EET92002, Yamato6903 and Karoonda) were measured by a stepped‐combustion method. Neon and Ar were also measured for the same samples. Two types of isotopically light N were observed. One of them is labile N released at low temperatures (∼300 °C). This N is observed
Naoji Sugiura, Shigeo Zashu
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Isotopic Variability of Nitrogen in Lunar Regolith

Science, 2001
Hashizume et al . ([1][1]) claim that the distribution and isotopic composition of nitrogen in the lunar regolith can be explained by a two-component mixing model. Their report, however, fails to discuss the bulk of existing relevant data—data that show unequivocally that the conclusions in ([1 ...
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Distribution of Isotopic Nitrogen in Nitrogen Gas During Denitrification

Nature, 1961
Equations are presented which permit calculation of the mole-fraction of nitrogen gas evolved from soil into an atmosphere containing nitrogen even though the amount of nitrogen-15 in the source material changes as a result of mixture with other soil nitrogen.
R. D. HAUCK, D. R. BOULDIN
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Nitrogen isotope biogeochemistry of thermal springs

Organic Geochemistry, 1984
Abstract Distinct biochemical pathways for nitrogen in living organisms can be detected by stable isotope tracers and may be useful in the interpretation of kerogen from ancient, sedimentary rocks. The organic matter in stromatolite growths of thermal springs was studied as a modern analog of these ancient kerogens.
Marilyn L.F. Estep, Stephen A. Macko
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Nitrogen isotopic compositions of iron meteorites

Geochimica et Cosmochimica Acta, 1993
Iron meteorites analyzed in this study have nitrogen concentrations 70 microg/g or less and delta N-15 from -90 to +150 percent. Although the iron meteorites have a large range of delta N-15, most have values more negative than -50 percent. The nitrogen isotopic compositions were established by cosmochemical processes and were little modified by ...
Carol A Prombo, Robert N Clayton
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