Nitrogen isotopic composition of planktonic foraminifera from the modern ocean and recent sediments

Ren, Haojia; Sigman, Daniel M.; Thunell, Robert C.; Prokopenko, Maria G.

doi:10.4319/lo.2012.57.4.1011

Cited by 68 publications

(104 citation statements)

References 62 publications

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“…If the corals behaved as a typical heterotroph, their δ 15 N would be 3-4‰ higher than that of their food source (Deniro and Epstein, 1981;Minagawa and Wada, 1984). On the contrary, the relatively low CS-δ 15 N of the Hog Reef corals is consistent with their low-δ 15 N metabolic ammonium being recycled by the symbionts rather than being effluxed to the environment, causing most coral N loss to be channeled through non-fractionating mechanisms (Reynaud et al, 2009;Ren et al, 2012).…”

Section: Bermuda Cs-δ 15 N and Plankton δ 15 Nmentioning

confidence: 63%

“…However, we argue that this difference is more easily explained by a much reduced ammonium excretion out of the symbiotic corals than non-symbiotic corals (Szmant-Froelich and Pilson, 1984): low-δ 15 N ammonium is retained within the symbiotic corals, causing a low tissue δ 15 N relative to non-symbiotic corals. Similar explanations have been applied to the δ 15 N difference between symbiotic and non-symbiotic foraminifera (Ren et al, 2012).…”

Section: Bermuda Cs-δ 15 N and Plankton δ 15 Nmentioning

confidence: 72%

“…To characterize the effect of the cleaning, we compared the NaOCl cleaning protocol with an analogous persulfate-based cleaning used for foraminifera-bound N isotope analyses (Ren et al, 2012) and with no cleaning. The coral standard cleaned by either method has much lower nitrogen content and quite different CS-δ 15 N than uncleaned standard (Figure 1), indicating that cleaning is critical ϭϯ in removing contaminant N. We observe no difference between the two cleaning protocols, indicating that both protocols are appropriate.…”

Section: Methods Validationmentioning

confidence: 99%

See 2 more Smart Citations

Isotopic composition of skeleton-bound organic nitrogen in reef-building symbiotic corals: A new method and proxy evaluation at Bermuda

Wang

Sigman

Cohen

et al. 2015

Geochimica et Cosmochimica Acta

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Section: Bermuda Cs-δ 15 N and Plankton δ 15 Nmentioning

confidence: 63%

Section: Bermuda Cs-δ 15 N and Plankton δ 15 Nmentioning

confidence: 72%

Section: Methods Validationmentioning

confidence: 99%

See 1 more Smart Citation

Isotopic composition of skeleton-bound organic nitrogen in reef-building symbiotic corals: A new method and proxy evaluation at Bermuda

Wang

Sigman

Cohen

et al. 2015

Geochimica et Cosmochimica Acta

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“…Yet, the average modelpredicted δ 15 N of newly produced NO − 3 (δ 15 N NTR ) (Fig. 5) ranged from −3.1 to +1.1 ‰ (standard error typically ±0.3 to 0.4 ‰), generally lower than that expected based on the δ 15 N of sinking organic matter from the surface ocean of ∼ +3.7 ‰ (Altabet, 1988(Altabet, , 1989Knapp et al, 2005;Ren et al, 2012). Values of δ 15 N NTR >+1 ‰ were only observed just above the O 2 minimum at sites 2B and 3D (Fig.…”

Section: Model-predicted Values Of δ 15 N Ntr : Implications For N Somentioning

confidence: 96%

Nitrogen cycling in the deep sedimentary biosphere: nitrate isotopes in porewaters underlying the oligotrophic North Atlantic

et al. 2015

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Abstract. Nitrogen (N) is a key component of fundamental biomolecules. Hence, its cycling and availability are central factors governing the extent of ecosystems across the Earth. In the organic-lean sediment porewaters underlying the oligotrophic ocean, where low levels of microbial activity persist despite limited organic matter delivery from overlying water, the extent and modes of nitrogen transformations have not been widely investigated. Here we use the N and oxygen (O) isotopic composition of porewater nitrate (NO − 3 ) from a site in the oligotrophic North Atlantic (Integrated Ocean Drilling Program -IODP) to determine the extent and magnitude of microbial nitrate production (via nitrification) and consumption (via denitrification). We find that NO − 3 accumulates far above bottom seawater concentrations (∼ 21 µM) throughout the sediment column (up to ∼ 50 µM) down to the oceanic basement as deep as 90 m b.s.f. (below sea floor), reflecting the predominance of aerobic nitrification/remineralization within the deep marine sediments. Large changes in the δ 15 N and δ 18 O of nitrate, however, reveal variable influence of nitrate respiration across the three sites. We use an inverse porewater diffusion-reaction model, constrained by the N and O isotope systematics of nitrification and denitrification and the porewater NO − 3 isotopic composition, to estimate rates of nitrification and denitrification throughout the sediment column. Results indicate variability of reaction rates across and within the three boreholes that are generally consistent with the differential distribution of dissolved oxygen at this site, though not necessarily with the canonical view of how redox thresholds separate nitrate regeneration from dissimilative consumption spatially. That is, we provide stable isotopic evidence for expanded zones of co-occurring nitrification and denitrification. The isotope biogeochemical modeling also yielded estimates for the δ 15 N and δ 18 O of newly produced nitrate (δ 15 N NTR (NTR, referring to nitrification) and δ 18 O NTR ), as well as the isotope effect for denitrification ( 15 ε DNF ) (DNF, referring to denitrification), parameters with high relevance to global ocean models of N cycling. Estimated values of δ 15 N NTR were generally lower than previously reported δ 15 N values for sinking particulate organic nitrogen in this region. We suggest that these values may be, in part, related to sedimentary N 2 fixation and remineralization of the newly fixed organic N. Values of δ 18 O NTR generally ranged between −2.8 and 0.0 ‰, consistent with recent estimates based on lab cultures of nitrifying bacteria. Notably, some δ 18 O NTR values were elevated, suggesting incorporation of 18 O-enriched dissolved oxygen during nitrification, and possibly indicating a tight coupling of NH + 4 and NO − 2 oxidation in this metabolically sluggish environment. Our findings indicate that the production of organic matter by in situ autotrophy (e.g., nitrification, nitrogen fixation) supplies a large fraction of the...

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“…Some cryptic species, however, are not distinguished from one another based on easily identifiable morphological differences (Knowlton, 1993). Orbulina universa (d'Orbigny), a species commonly used in climate proxy development (Spero and Williams, 1988;Sanyal et al, 1996;Spero et al, 1997;Bemis et al, 1998;Lea et al, 1999;Ren et al, 2012), has three known genetic variants -Caribbean (Type I), Sargasso (Type II) and Mediterranean (Type III; Darling et al, 1996Darling et al, , 1997de Vargas et al, 1997de Vargas et al, , 1999Morard et al, 2009). Several studies have mapped the geographic distribution of O. universa genotypes in the North and South Atlantic, Caribbean Sea, Western Pacific Ocean, Southern California Bight and Indian Ocean de Vargas et al, 1997de Vargas et al, , 1999Morard et al, 2009Morard et al, , 2013, and have linked their relative abundances to changes in sea surface chlorophyll concentrations (de Vargas et al, 1999).…”

Section: Overviewmentioning

confidence: 99%

Morphometric and stable isotopic differentiation of Orbulina universa morphotypes from the Cariaco Basin, Venezuela

Marshall

Thunell

Spero

et al. 2015

Marine Micropaleontology

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Biometric characteristics of Orbulina universa (d'Orbigny) were used to differentiate two morphotypes present in sediment trap samples collected from the Cariaco Basin, Venezuela. Specifically, wall thickness and weight-area relationships were used to separate shells into thin (M thin ) and thick (M thick ) morphotypes. M thick (mean thickness = 19-41 μm) comprises 75% of the total O. universa in these samples and has morphometric characteristics similar to that of the previously described Type I Caribbean genotype, whereas M thin (mean thickness = 6-22 μm) is comparable to the Type III Mediterranean genotype. The flux of M thick increases during periods of upwelling, whereas M thin flux shows no systematic relationship with changing hydrographic regimes in the basin. The δ 18O and δ 13 C of M thick are on average 0.34‰ higher and 0.38‰ lower, respectively, than those of M thin , suggesting that they calcify their final spherical chamber at different depths in the water column and/or differ in their vital effects on shell geochemistry. Additionally, the absolute offset in the stable isotopic compositions of the two morphotypes varies as a function of surface ocean stratification. During periods of upwelling, the δ

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Nitrogen isotopic composition of planktonic foraminifera from the modern ocean and recent sediments

Cited by 68 publications

References 62 publications

Isotopic composition of skeleton-bound organic nitrogen in reef-building symbiotic corals: A new method and proxy evaluation at Bermuda

Isotopic composition of skeleton-bound organic nitrogen in reef-building symbiotic corals: A new method and proxy evaluation at Bermuda

Nitrogen cycling in the deep sedimentary biosphere: nitrate isotopes in porewaters underlying the oligotrophic North Atlantic

Morphometric and stable isotopic differentiation of Orbulina universa morphotypes from the Cariaco Basin, Venezuela

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