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171 results for “carbon isotopes”
ODP 1084 Hydrogen and Carbon Leaf Wax Isotopes
<p>This is the temporary home for ODP 1084 leaf wax isotope data. Upon publication, this data will be uploaded to the NOAA Paleo Database.</p>
Lipid extraction alters amino acid composition and bulk, but not amino acid, carbon and nitrogen isotope values
<p>Rationale: Concerns exist over observed shifts in value and variance of nitrogen isotopes following physicochemical extraction of lipids from organic matter. The mechanisms behind these apparent changes in bulk tissue δ15N values are not fully understood yet have major implications for analytical costs and integrity of data interpretations.</p> <p>Methods: Changes in proximate analysis, amino acid composition, C:N ratios, bulk tissue and amino acid δ13C and δ15N values, and resulting isotope‐based food web metrics were compared between lipid‐intact and lipid‐extracted muscle tissue of fishes spanning <1% to >20% muscle fat content to identify mechanisms of nitrogen isotope fractionation associated with physicochemical lipid extraction.</p> <p>Results: Bulk δ13C and δ15N values increased and %N, C:N ratios and crude protein content decreased following lipid extraction. Resulting bulk isotope niche spacing and overlap varied significantly between lipid‐intact and lipid‐extracted tissues. While amino acid composition significantly changed during lipid extraction, particularly for lipid‐associated amino acids (e.g., Glu, Lys, Ser), individual amino acid δ13C and δ15N values, and their associated compound‐specific isotope analysis of amino acids (CSIA‐AA)‐based food web metrics, did not.</p> <p>Conclusions: Physicochemical lipid extraction caused significant tissue composition changes (e.g., leaching of amino acids and 15N‐deplete nitrogenous waste) that affected δ13C and δ15N values and tissue %C and %N beyond simply removing lipids. However, lipid extraction did not alter individual amino acid δ13C or δ15N values or their associated CSIA‐AA‐based food web metrics.</p>
Insights into subduction-zone fluid-rock interactions and carbon recycling from magnesium isotopes of subducted ophiolitic mélanges in the Arabian-Nubian Shield
<p><span>Table S1:</span><span> Major element concentrations (in wt%) and Mg isotopic compositions (‰) for the ANS subducted ophiolitic mélanges.</span></p> <p><span>Table S2: Trace element concentrations (ppm) for the ANS subducted ophiolitic mélanges.</span></p>
Stable isotope data for oxygen and hydrogen and electron microprobe data in phyllosilicates and clumped isotopes of carbonates from paleosols, Illinois Basin, USA
<p>Datasets including stable isotope data for oxygen and hydrogen of phyllosilicates, electron microprobe data of phyllosilicates, and clumped isotope data of carbonates from paleosols of the Illinois Basin, accompanying publication.</p>
Dataset S1 - Noelaerhabdaceae organic carbon isotope culture data compilation
<p class="BodyA">The carbon isotope fractionation in algal organic matter (E<sub>p</sub>), including the long-chain alkenones produced by the coccolithophorid family Noelaerhabdaceae, is used to reconstruct past atmospheric CO<sub>2</sub> levels. The conventional proxy linearly relates E<sub>p</sub> to changes in cellular carbon demand relative to diffusive CO<sub>2</sub> supply, with larger E<sub>p</sub> values occurring at lower carbon demand relative to supply (<i>i</i>.<i>e</i>. abundant CO<sub>2</sub>). However, the response of <i>Gephyrocapsa oceanica</i>, one of the dominant alkenone producers of the last few million years, has not been studied closely. Here we subject <i>G. oceanica</i> to various CO<sub>2</sub> levels by increasing pCO<sub>2</sub> in the culture headspace, as opposed to increasing dissolved inorganic carbon (DIC) and alkalinity concentrations at constant pH. We note no substantial change in physiology, but observe an increase in E<sub>p</sub> as carbon demand relative to supply decreases, consistent with DIC manipulations. We compile existing Noelaerhabdaceae E<sub>p</sub> data and show that the diffusive model poorly describes the data. A meta-analysis of individual treatments (unique combinations of lab, strain, and light conditions) shows that the slope of the E<sub>p</sub> response depends on the light conditions and range of carbon demand relative to CO<sub>2</sub> supply in the treatment, which is incompatible with the diffusive model. We model E<sub>p</sub> as a multilinear function of key physiological and environmental variables and find that both photoperiod duration and light intensity are critical parameters, in addition to CO<sub>2</sub> and cell size. While alkenone carbon isotope ratios indeed record CO<sub>2</sub> information, irradiance and other factors are also necessary to properly describe alkenone E<sub>p</sub>.</p>
Isotopic evidence for increased carbon and nitrogen exchanges between peatland plants and their symbiotic microbes with rising atmospheric CO2 concentrations since 15000 cal. yr BP
<p>Whether nitrogen (N) availability will limit plant growth and removal of atmospheric CO<sub>2</sub> this century is controversial. Studies have suggested that N could progressively limit plant growth, as trees and soils accumulate N in slowly cycling biomass pools in response to increases in carbon sequestration. However, a question remains over the longer-term (decadal to century) feedbacks between climate, CO<sub>2</sub> and plant N uptake. The symbiosis between plants and microbes can help plants with mycorrhizal N uptake or biological N2 fixation – the pathway through which N can be rapidly brought into ecosystems and thereby partially or completely alleviate N limitation on plant productivity. Here we present results for plant N isotope composition (δ<sup>15</sup>N) in a peat core that dates to 15000 cal. yr BP to ascertain ecosystem-level N cycling responses to rising atmospheric CO<sub>2</sub> concentrations in the past. We found that an increase in atmospheric CO<sub>2</sub> concentration happened with a decrease in δ<sup>15</sup>N values of both <em>Sphagnum</em> moss and Ericaceae over this time period when constrained for climatic factors. A modern experiment demonstrated that δ<sup>15</sup>N of <em>Sphagnum</em> mosses decreased with increasing N2 fixation rates. These findings suggested that N2 fixation in <em>Sphagnum</em> moss by symbiosis with cyanobacteria and N uptake in Ericaceae by symbiosis with mycorrhizal fungi both likely increased with rising atmospheric CO<sub>2</sub> concentrations, highlighting a longer-term feedback mechanism whereby N constraints on terrestrial carbon storage can be overcome. </p>
Data compilation of stable and radiactive carbon, Nd isotopes, and Pa and Th of the Last Glacial Maxmium and last deglaciation
<p>Proxy data compilations of <span class="math-tex">\(\delta^{13}C\)</span>, benthic-planktic <sup>14</sup>C ages, Nd isotopes, and Pa and Th of the Last Glacial Maximum (LGM) and last deglaciation as used in Pöppelmeier et al. (2023).</p> <p>Pöppelmeier, F., Jeltsch-Thömmes, A., Lippold, J., Joos, F., & Stocker, T. F. (2023). Multi-proxy agreement on Atlantic circulation dynamics since the last ice age.</p>
Data from: An expanded Smithian-Spathian (Early Triassic) boundary from a reefal build-up record in Oman: Implications for conodont taxonomy, high-resolution biochronology and the carbon isotope record
<p><span>Some 2.7 Ma after the Permian-Triassic boundary mass extinction (PTME), a stepwise extinction of the nekton (ammonoids and conodonts) ended at the Smithian-Spathian boundary (SSB) during an episode of climate cooling. SSB records from continental shelves are usually affected by an unconformity, suggesting a forced regression of glacio-eustatic origin. Here, we document a new 30 m-thick SSB section from Jebel Aweri (Batain Plain, Oman) that provides an exceptionally complete and expanded record preserved in an exotic block. Most of this SSB section consists of metazoan reefal build-ups that formed in shallow water on an offshore sea mount. In Wadi Musjah (Hawasina nappes, Oman), another exotic block records the SSB in a deeper water setting represented by Hallstatt-type facies. These two sections provide a unique perspective on the early Spathian rapid re-diversification of conodonts. They led to a thorough revision of conodont taxonomy around the SSB and to the construction of the highest resolution biochronological scheme for this time interval in the Tethys. A total of five SSB sections from Oman representing both offshore sea mounts and lower slope deposits were included in a high-resolution, quantitative Unitary Associations analysis. The resulting 8 conodont biozones are intercalibrated with ammonoid zones and with the carbonate carbon isotope record ultimately placing the SSB in the interval of separation between UAZ<sub>3</sub> and UAZ<sub>4</sub>. Only the association of <em>Nv. pingdingshanensis</em> with <em>Ic. crassatus</em> can be used to unambiguously characterize the base of the Spathian.</span></p>
Intra-annual-tree-ring-stable-carbon-and-oxygen-isotope-of-Chinese-pine-in-Helan-Mountains
<p>The data are intra-annual series of tree-ring stable carbon (δ<sup>13</sup>Ccor) and oxygen (δ<sup>18</sup>O) isotopes from Chinese pine (<em>Pinus tabuliformis</em>) in Helan Mountains</p>
Contents and isotope carbon compositions (δ13C) of main biochemical fractions in organs at different growth stages in Phyllostachys edulis
<p><em><span>Phyllostachys edulis</span></em><span> is a spectacularly fast-growing species that completes its height growth within </span><span>two</span><span> months after the shoot emerges </span><span>without producing leaves</span><span> (fast-growing period, FGP). This phase was considered heterotrophic, the carbon necessary for the growth being transferred from the mature culms via the rhizomes, although previous studies observed key enzymes and anatomical features related to C<sub>4</sub>-carbon fixation in developing culms. </span><span>We tested whether C<sub>4</sub>-photosynthesis or dark-CO2 fixation through anaplerotic reactions significantly contributes to the FGP, resulting in differences in the natural abundance of </span><span>δ<sup>13</sup>C</span><span> in bulk organic matter and organic compounds. Further, pulse-<sup>13</sup>CO<sub>2</sub>-labelling was performed on developing culms, either from the surface or from the internal hollow, to ascertain whether significant CO<sub>2</sub> fixation occurs in developing culms.</span><span> δ<sup>13</sup>C of</span><span> young </span><span>shoots and developing culms were higher (-26.3–-26.9‰) </span><span>compared to all organs of mature bamboos (-28.4</span><span>–</span><span>-30.1</span><span>‰). </span>Developing culms contained chlorophylls, most observed in the skin tissues. After <span>pulse-<sup>13</sup>CO<sub>2</sub>-labelling, t</span>he polar fraction extracted from the skin tissues was slightly enriched in <sup><span>13</span></sup><span>C, </span>and only a weak <sup><span>13</span></sup><span>C </span>enrichment was observed in inner tissues<span>. Main carbon source sustaining the FGP was not assimilated by the developing culm, while a </span><span>limited anaplerotic fixation of respired CO<sub>2</sub></span><span> cannot be excluded and is </span>more likely than <span>C<sub>4</sub>-</span>photosynthetic carbon fixation<span>.</span></p>
Data for: Sources, pathways and behaviour of cave air CO2 using carbon isotopes
<p>Raw data for all figures in the manuscript by Krajnc et al. to be published by Geochimica et Cosmochimica Acta as "Sources, pathways and behaviour of cave air CO<sub>2</sub> using carbon isotopes".</p>
Feather nitrogen and carbon stable isotope (d15N and d13C) values for Golden-crowned Sparrows
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Data from: Isotopic composition of particulate black carbon in the northern Indian Ocean
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Bulk Carbon and Amino Acid nitrogen isotope data from Baltic cod (Gadus morhua) and European flounder (Platichthys flesus) muscle tissue samples from the western and central Baltic Sea
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Lipid extraction alters amino acid composition and bulk, but not amino acid, carbon and nitrogen isotope values
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Fatty acid and carbon isotopic data for: Use of essential vs. non-essential fatty acids during flight in monarch butterflies: Implications for the importance of nectaring during migration
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Data from: An expanded Smithian-Spathian (Early Triassic) boundary from a reefal build-up record in Oman: Implications for conodont taxonomy, high-resolution biochronology and the carbon isotope record
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Bulk tissue versus amino acid carbon stable isotopes to reveal the diet and basal resource use of an invasive rodent
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Data from: Arithmetic normalization models for the effects of lipid on carbon stable isotope values in silver carp (Hypophthalmichthys molitrix) tissue
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Data from: Carbon isotope trends across a century of herbarium specimens suggest CO2 fertilization of C4 grasses
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