A method for nitrite removal in nitrate N and O isotope analyses

Granger, Julie; Sigman, Daniel M.; Prokopenko, Maria G.; Lehmann, Moritz F.; Tortell, Philippe D.

doi:10.4319/lom.2006.4.205

Cited by 78 publications

(61 citation statements)

References 23 publications

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“…When the NO 2 -/(NO 2 -? NO 3 -) ratio of the samples exceeded 0.05, NO 2 -was removed by reaction with ascorbic acid prior to the incubation (Granger et al 2006). DIC was measured by a TOC analyzer (Shimadzu, TOC-5000A).…”

Section: Methodsmentioning

confidence: 99%

Longitudinal distribution of nitrate δ15N and δ18O in two contrasting tropical rivers: implications for instream nitrogen cycling

et al. 2009

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The longitudinal variations in the nitrogen (d 15 N) and oxygen (d 18 O) isotopic compositions of nitrate (NO 3 -), the carbon isotopic composition (d 13 C) of dissolved inorganic carbon (DIC) and the d 13 C and d 15 N of particulate organic matter were determined in two Southeast Asian rivers contrasting in the watershed geology and land use to understand internal nitrogen cycling processes. The d 15 N NO 3 became higher longitudinally in the freshwater reach of both rivers. The d 18 O NO 3 also increased longitudinally in the river with a relatively steeper longitudinal gradient and a less cultivated watershed, while the d 18 O NO 3 gradually decreased in the other river. A simple model for the d 15 N NO 3 and the d 18 O NO 3 that accounts for simultaneous input and removal of NO 3 -suggested that the dynamics of NO 3 -in the former river were controlled by the internal production by nitrification and the removal by denitrification, whereas that in the latter river was significantly affected by the anthropogenic NO 3 -loading in addition to the denitrification and/or assimilation. In the freshwater-brackish transition zone, heterotrophic activities in the river water were apparently elevated as indicated by minimal dissolved oxygen, minimal d 13 C DIC and maximal pCO 2 . The d 15 N of suspended particulate nitrogen (PN) varied in parallel to the d 15 N NO 3 there, suggesting that the biochemical recycling processes (remineralization of PN coupled to nitrification, and assimilation of NO 3 --N back to PN) played dominant roles in the instream nitrogen transformation. In the brackish zone of both rivers, the d 15 N NO 3 displayed a declining trend while the d 18 O NO 3 increased sharply. The redox cycling of NO 3 -/NO 2 -and/or deposition of atmospheric nitrogen oxides may have been the major controlling factor for the estuarine d 15 N NO 3 and d 18 O NO 3 , however, the exact mechanism behind the observed trends is currently unresolved.

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Section: Methodsmentioning

confidence: 99%

Longitudinal distribution of nitrate δ15N and δ18O in two contrasting tropical rivers: implications for instream nitrogen cycling

et al. 2009

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“…If nitrite is present in seawater, even at levels r 0.5% of nitrateþnitrite, it can noticeably affect the measured δ 18 O of nitrateþnitrite Granger and Sigman, 2009;Granger et al, 2006). This is because, during bacterial conversion to N 2 O, nitrite is subject to a smaller fractional loss of O atoms than nitrate (3/4 versus 5/6) such that O isotopic fractionation during nitrite reduction to N 2 O is lower (by $ 25‰) than that for N 2 O generated from nitrate with the same initial δ 18 O To investigate the influence of ambient nitrite on the isotopic composition of nitrateþnitrite, duplicate aliquots of all samples from the surface to 500 m, as well as a number of deeper samples, were treated with sulfamic acid to remove nitrite according to the protocol of Granger and Sigman (2009).…”

Section: Isotopic Analysis Of Nitrate þNitrite and Nitratementioning

confidence: 99%

Vertical decoupling of nitrate assimilation and nitrification in the Sargasso Sea

Fawcett

Ward

Lomas

et al. 2015

Deep Sea Research Part I: Oceanographic Research Papers

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“…The detection limit was 0.1 µM. Any NO − 2 detected was subsequently removed prior to NO − 3 isotope analysis with ascorbate, and the resultant NO gas was purged with an inert gas stream (Granger et al, 2006).…”

Section: Sample Collectionmentioning

confidence: 99%

Coupled nitrate N and O stable isotope fractionation by a natural marine plankton consortium

et al. 2015

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The stable nitrogen (N) and oxygen (O) nitrification. Differences in irradiance in the fall incubations resulted in slightly reduced nitrate consumption at low light but had no distinguishable impact on the N isotope effect ( 15 ε) associated with NO − assimilation, which ranged between 5 and 8‰. The 3 late-summer community incubations, in contrast, showed significantly reduced growth rates at low light and more elevated 15 ε of 11.9 ± 0.4‰, compared to 8.4 ± 0.3‰ at high-light conditions. The seasonal differences could reflect physiological adaptations of the fall plankton community to reduced irradiance, such that their incubation at low light did not elicit the increase in proportional cellular nitrate efflux required to raise the isotope effect. In both the fall and summer incubations, the ratio of the coincident rises in the 15 δ N and 18 δ O of NO − was comparable to previous monoculture phytoplankton experiments, δ O: 15 δ N is expected if nitrification occurs concomitantly with nitrate assimilation. The lack of such decoupling is best explained by the absence of significant nitrification in any of our study's treatments, an interpretation supported by our inability to identify any tracer 15 N and 18 O uptake into the NO − pool in the late-summer community incubations.

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A method for nitrite removal in nitrate N and O isotope analyses

Cited by 78 publications

References 23 publications

Longitudinal distribution of nitrate δ15N and δ18O in two contrasting tropical rivers: implications for instream nitrogen cycling

Longitudinal distribution of nitrate δ15N and δ18O in two contrasting tropical rivers: implications for instream nitrogen cycling

Vertical decoupling of nitrate assimilation and nitrification in the Sargasso Sea

Coupled nitrate N and O stable isotope fractionation by a natural marine plankton consortium

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