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141 results for “isotopic composition”
Climate Change Across Seasons Experiment (CCASE) at the Hubbard Brook Experimental Forest: Branch Xylem Water Isotopic Composition
Natural abundance stable isotopes of oxygen, hydrogen, and deuterium-excess in branch xylem water were measured within the Climate Change Across Seasons Experiment (CCASE) plots. There are six plots total (each 11 x 14 m). Two are warmed 5 degrees C throughout the growing season (Plots 3 and 4). Two others are warmed 5 degrees C in the growing season and have snow removed during winter to induce soil freezing and then warming cables turn on to create thaws; each soil freeze/thaw cycle includes 72-hours of soil freezing followed by 72-hours of thaw (Plots 5 and 6). Four kilometers (2.5 mi) of heating cable are buried in the soil to warm these four plots. Two additional plots serve as controls for our experiment (Plots 1 and 2). This data set includes natural abundance stable isotopes of oxygen, hydrogen, and deuterium-excess in branch xylem water from 2018. These data were gathered as part of the Hubbard Brook Ecosystem Study (HBES). The HBES is a collaborative effort at the Hubbard Brook Experimental Forest, which is operated and maintained by the USDA Forest Service, Northern Research Station.
Climate Change Across Seasons Experiment (CCASE) at the Hubbard Brook Experimental Forest: Soil Water Isotopic Composition
Natural abundance stable isotopes of oxygen and hydrogen in soil water were measured adjacent to the Climate Change Across Seasons Experiment (CCASE) plots. There are six plots total (each 11 x 14 m). Two are warmed 5 degrees C throughout the growing season (Plots 3 and 4). Two others are warmed 5 degrees C in the growing season and have snow removed during winter to induce soil freezing and then warming cables turn on to create thaws; each soil freeze/thaw cycle includes 72-hours of soil freezing followed by 72-hours of thaw (Plots 5 and 6). Four kilometers (2.5 mi) of heating cable are buried in the soil to warm these four plots. Two additional plots serve as controls for our experiment (Plots 1 and 2). This data set includes natural abundance stable isotopes of oxygen and hydrogen in soil water from 2018. These data were gathered as part of the Hubbard Brook Ecosystem Study (HBES). The HBES is a collaborative effort at the Hubbard Brook Experimental Forest, which is operated and maintained by the USDA Forest Service, Northern Research Station.
McMurdo Dry Valleys Halogen chemistry and isotopic composition in McMurdo lake waters and pore fluids
As part of a collaborative investigation between researchers at Rice University, Arkansas State University, University of Rochester, and Ohio State University, lakes of the McMurdo Dry Valleys were sampled at discreet depth intervals during the 2005-2006 field season.  Sample splits were subsequently analyzed for chemical and isotopic composition of both gases and dissolved  ions, as well as dissolved organic carbon. In addition, cryogenic salts were sampled in the surrounding lake shores in order to determine the salt sources. Gravity cores were also obtained and the pore waters were collected by centrifuging the wet sediment.  Presented  in this file are the dissolved halogens :chloride, bromide, and total iodine in lake waters and pore waters. The isotopic composition of I-129 and Cl-36 are also presented for these same samples, as are the molar ratios of I-129/I-127, and Cl-36/Cl-37.  Alkalinity was also determined in order to subsequently investigate the relationship between the oxidation of organic matter and the release of iodine into the lake waters.
McMurdo Dry Valleys Iodine content and I-129 isotopic composition in McMurdo lake-bottom sediments
As part of a collaborative investigation between researchers at Rice University, Arkansas State University, University of Rochester, and Ohio State University, lakes of the McMurdo Dry Valleys were sampled at discreet depth intervals during the 2005-2006 field season.  Sample splits were subsequently analyzed for chemical and isotopic composition of both gases and dissolved  ions, as well as dissolved organic carbon. In addition, cryogenic salts were sampled in the surrounding lake shores in order to determine the salt sources. Gravity cores were also obtained and the pore waters were collected by centrifuging the wet sediment.  Presented  in this file is the total iodine content and I-129 isotopic composition of lake-bottom sediments from Lakes Joyce and Fryxell. An attempt was made to determine the  iodine and chlorine isotopic content  of gypsum cored from the bottom of Lake Vanda, but the total iodine content was below detection.       Â
South Bay, VA, seagrass sediment and autotroph source stable isotope compositions, 2014
Abstract text from Oreska et al. (2017): Non-seagrass sources account for 50% of the sediment organic carbon (SOC) in many seagrass beds, a fraction that may derive from external organic matter (OM) advected into the meadow and trapped by the seagrass canopy or produced in situ. If allochthonous carbon fluxes are responsible for the non-seagrass SOC in a given seagrass bed, this fraction should decrease with distance from the meadow perimeter. Identifying the spatial origin of SOC is important for closing seagrass carbon budgets and "blue carbon" offset-credit accounting, but studies have yet to quantify and map seagrass SOC stocks by carbon source. We measured sediment d13C, d15N, and d34S throughout a large (6 km2), restored Zostera marina (eelgrass) meadow and applied Bayesian mixing models to quantify total SOC contributions from possible autotroph sources, Z. marina, Spartina alterniflora, and benthic microalgae (BMA). Z. marina accounted for <40% of total meadow SOC, but we did not find evidence for outwelling from the fringing S. alterniflora salt-marsh or OM advection from bare subtidal areas. S. alterniflora SOC contributions averaged 10% at sites both inside and outside of the meadow. The BMA fraction accounted for 51% of total meadow SOC and was highest at sites furthest from the bare subtidal-meadow edge, indicative of in situ production.
Miocene paleotopography and paleoclimate based on paired stable isotope compositions in Namling Basin, south Tibet
<p>This supporting information contains four datasets asTable 1 in the main text and Table S1, Table S2, and Table S3 in the supplementary file. Table S1 is the zircon U-Pb dating of two tuff samples. Both samples were collected in 2016 at the bottom and at the top of the measured section to constrain the precisely formed timing of the samples. U-Pb dating was processed by laser ablation inductively coupled plasma-mass spectrometer (LA-ICP-MS) and calculated by the GLITTER_V4.0.</p> <p>Table S2 is a summary Miocene δ<sup>2</sup>H data, δ<sup>18</sup>O data, and vegetation associations in the Miocene Tibetan Plateau basins from literature. These data were from our study in Namling Basin and previous work (Spicer et al., 2003; Currie et al., 2016; Khan et al., 2014); Lunpola Basin (Polissar et al., 2009; Sun et al., 2014), Hoh Xil Basin (Polissar et al., 2009; Sun et al., 2015; Li et al., 2015), and Qaidam basin (Zhuang et al., 2014; Miao et al., 2013) as well as the biotite δ2H data from Himalaya (Gebélin et al., 2013). Paleometeoric water δD<sub>w</sub> values are calculated by applying the average established and local apparent fractionation factor of -111±14‰ in the Namling, Lunpola and Hoh Xil basins and -102‰ in the Qaidam Basin (Zhuang et al., 2014). b. Paleometoric water δ<sup>18</sup>O<sub>w</sub> values are calculated by the calcite-water equation (Kim and O'Neil, 1997) with carbonate forming temperatures of 14.6±3.6°C in the Namling Basin, Lunpola Basin and Hoh Xil Basin (Deng et al., 2012; Sun et al., 2015; Ingalls et al., 2017).</p> <p>Table S3 is a summary of the stable isotope of the surface water across the Tibetan Plateau. These data were from the previous literature (Quade et al., 2011; Hren et al., 2009; Bershaw et al., 2012).</p>
The oxygen isotope compositions of large numbers of small cosmic spherules: Implications for their sources and the isotopic composition of the upper atmosphere
<p>Cosmic spherules are micrometeorites that melt at high altitude as they enter Earth's atmosphere and their oxygen isotope compositions are partially or completely inherited from the upper atmosphere, depending on the heating experienced and the nature of their precursor materials. In this study, the <b>three oxygen isotope</b> compositions of 137 <b>cosmic spherules are</b> determined using 277 in-situ analyses by ion probe. Particles of each different type of cosmic spherule (scoriaceous, porphyritic, cryptocrystalline, barred, glass, calcium aluminium and titanium (CAT), G-type and I-type) in the diameter range ~52–480mm were analysed. The results confirm that the <b>three</b> oxygen isotope compositions of melted <b>micrometeorites</b> reflect a combination of their precursor composition, exchange with the atmosphere and mass fractionation owing to evaporation during entry heating. The data <b>appear to </b>reveal an increase in average δ<sup>18</sup>O values of silicate dominated (S-type) spherules in the series scoriaceous<porphyritic<barred<glass<CAT spherules (~20, 22, 25, 26 and 50‰) that is consistent with the evolution of oxygen isotopes by mass fractionation owing to increased average entry heating. The trend of δ<sup>17,18</sup>O is broadly parallel to the terrestrial fractionation line and thus suggests mass fractionation dominates changes in isotopic composition, with atmospheric exchange a less significant effect. The D<sup>17</sup>O values of spherules, therefore, are mostly preserved and suggest that ~80% of particles are related to the carbonaceous chondrites (CC) and are probably samples of C-type asteroids. The genetic relationships between different S-types can also be determined with scoriaceous, barred and cryptocrystalline spherules mostly having low D<sup>17</sup>O values <b>(≤0‰)</b> suggesting they are mainly derived from CC-like sources, whilst porphyritic mostly have positive D<sup>17</sup>O <b>(>0‰)</b> suggesting they are largely from ordinary chondrite (OC)-like sources related to S(IV)-type asteroids. Glassy and CAT-spherules have D<sup>17</sup>O values <b>indicating</b> they formed by intense entry heating of both CC and OC-like materials. I-type cosmic spherules have a narrow range of δ<sup>17</sup>O (~20–25‰) and δ<sup>18</sup>O (~38–48‰) values, with D<sup>17</sup>O (~0‰) <b>suggesting</b> their oxygen is obtained entirely from the Earth's atmosphere, albeit with significant mass fractionation owing to evaporation during entry heating. The observed range of δ<sup>18</sup>O with the size is suggested here to reflect entry angle with high values representing enhanced heating at high angle. Finally, G-type <b>cosmic spherules</b> have unexpected isotopic compositions suggesting little mass-fractionation from a CC-like source and are suggested to have sulphide-silicate precursors with relatively low melting temperatures. The results of this study provide a <b>vital assessment</b> of the <b>wider</b> population of extraterrestrial dust arriving <b>at the</b> Earth.</p>
A 4.5 year-long record of Svalbard water vapor isotopic composition documents winter air mass origin
<p>Isotopic data from the article in JGR A: A 4.5 year-long record of Svalbard water vapor isotopic composition documents winter air mass origin</p> <p><strong>CLDS_2020_ground_iso_vapor_1h.dat</strong></p> <p><strong>CLDS_2020_zeppelin_iso_vapor_1h.dat </strong></p> <p>first column: date in matlab format</p> <p>second column: humidity in ppmv</p> <p>thrid column: d18O in per mil</p> <p>forth column: dD in per mil</p> <p>fifth column: not to take into account</p> <p><strong>CLDS_2020_iso_precip.dat </strong></p> <p>first column: date in matlab format</p> <p>second column: temperature at noon in degre C</p> <p>thrid column: d18O in per mil</p> <p>forth column: dD in per mil</p> <p>fifth column:type of precip 1: water & 2 : snow & 3 : other (melt, etc.)</p>
dataset for: Carbonate content and stable isotopic composition of atmospheric aerosol carbon in the Canadian High Arctic
<p>Dataset related to publication of the same title in <a href="https://www.atmospheric-chemistry-and-physics.net/">Atmospheric Chemistry and Physics</a></p>
Dataset of: Deconvolving feeding niches and strategies of abyssal holothurians from their stable isotope, amino acid, and fatty acid composition
Open the record for dataset details and reuse information.
Spring tropical cyclones modulate near-surface isotopic compositions of atmospheric water vapour at Kathmandu, Nepal
<p>All these data have been published in a ACP paper. If you use these data in any conditions, please cite the following publicaiton: Adhikari, N., Gao, J., Zhao, A., Xu, T., Chen, M., Niu, X., and Yao, T.: Spring tropical cyclones modulate near-surface isotopic compositions of atmospheric water vapour at Kathmandu, Nepal, EGUsphere, https://doi.org/10.5194/egusphere-2023-2186, 2023.</p>
Global data compilation of seawater, authigenic and detrital radiogenic neodymium isotope composition since the Last Glacial Maximum
<p>The global radiogenic Neodymium isotope data compilation from:</p> <div> <div>Du J., Haley B. A. and Mix A. C. (2020) Evolution of the Global Overturning Circulation since the Last Glacial Maximum based on marine authigenic neodymium isotopes. <em>Quaternary Science Reviews</em> <strong>241</strong>, 106396.</div> </div>
Data from: Isotopic composition of particulate black carbon in the northern Indian Ocean
<p>The dataset contains the concentration and stable isotopic composition of particulate black carbon (PBC) in the surface waters of the northern Indian Ocean. Samples were collected during multiple cruises to the Northern Indian Ocean (locations, date and time are provided in the datasheet) along with end member sampling of riverine particulate. Surface water samples were filtered onto 0.7 micron GF/F filters (precombusted at 400 degree Celsius) and oven-dried. Particulate black carbon was estimated following the chemothermal oxidation (CTO - 375) method. Briefly, samples were treated using HCl fumes to remove inorganic carbon fractions followed by heating at 400 degree celsius for 24 hours in active airflow to remove the organic carbon fraction. The residual carbon (BC in micromoles per litre) and its isotopic composition (represented by delta notation in permil) was measured using an elemental analyzer (EA: Flash 2000, Thermo Scientific) connected to an isotope ratio mass spectrometer (IRMS: Delta V, Thermo Scientific). The precision of measurement by repeated analysis of standards was better than 10 % for PBC concentration and 0.1 permil for its isotopic composition. The data is associated with the manuscript accepted in Geophysical Research Letters titled, 'Isotopic evidence for degradation of particulate black carbon in the ocean.</p>
Year-round observations of stable carbon isotopic composition of diacids and related compounds in fine aerosols at Tianjin, North China – Data set
<p>To better understand the origins and photochemical processing of water-soluble organic aerosols in the Tianjin region, North China, we studied the stable isotopic composition (δ<sup>13</sup>C) of diacids, oxoacids, α-dicarbonyls, citric acid and fatty acids in fine aerosols (PM<sub>2.5</sub>) collected at an urban (Nankai District, ND; <em>n</em> = 121) and a suburban (Haihe Education Park, HEP; <em>n</em> = 40) sites in Tianjin from 5 July 2018 to 4 July 2019. The δ<sup>13</sup>C of diacids and related compounds were measured using a capillary gas chromatography (Agilent 7890B) coupled with isotope ratio mass spectrometry (GC-irMS) system. Based on seasonal variations in δ<sup>13</sup>C of selected species and linear relations with their concentrations and mass ratios, we found that the diacids and related compounds were mainly derived from fossil fuel including coal combustion and biomass burning and photochemical processing, preferably in gaseous- and aqueous-phases in warm (March-September) and cold (October-February) periods, respectively, in Tianjin, North China.</p>
Isotopic Fuel Compositions in the Sangamon200 Model
<p>The seven csv files each correspond to a different level of fuel burnup in the Sangamon200 (a 200 MWth pebble-bed HTGR) fuel pebbles. fresh_comp.csv provides the composition for UCO in fresh pebbles. 1pass_comp.csv provides the fuel composition in pebbles that have gone through one six month pass, 2pass_comp.csv have been through two six month passes, and so forth.</p>
The Relations between Summer Droughts/Floods and Oxygen Isotope Composition of Precipitation in Dongting Lake Basin
<p>This is the precipitation amount and stable isotope composition of precipitation data on monthly timescale from Jan 1979 to Dec 2017 over the Dongting Lake Basin, Central-shouthern China. This is simulated data from isoGSM2.</p> <p> </p>
Laboratory Assessment of the Impact of Chemical Oxidation, Mineral Dissolution, and Heating on the Nitrogen Isotopic Composition of Fossil-bound Organic Matter
<p>Results of laboratory experiments reported in the manuscript "<em>Laboratory Assessment of the Impact of Chemical Oxidation, Mineral Dissolution, and Heating on the Nitrogen Isotopic Composition of Fossil-bound Organic Matter</em>", published in the journal <em>Geochemistry, Geophysics, Geosystems</em></p>
Supplementary dataset for: Carbonate Clumped Isotope Constraints on Early Triassic NeoTethyan Seawater Oxygen Isotope Compositions and Temperatures
<p><span>The dataset includes data generated for the study titled:</span> <strong><span>Carbonate Clumped Isotope Constraints on Early Triassic NeoTethyan Seawater Oxygen Isotope Compositions and Temperatures</span></strong></p> <p><span>The Excel file includes </span></p> <ol> <li><span>Clumped isotope data for analyzed brachiopod calcites, bulk rock micrite, as well as analytical standards (Tables S1 and S2).</span></li> <li><span>Rare Earth element concentration data for brachiopod samples analyzed (Table S3)</span></li> <li><span>Element/Ca ratios for analyzed samples (Table S4).</span></li> </ol> <p> </p> <p> </p>
Biochemical and biophysical drivers of the hydrogen isotopic composition of carbohydrates and acetogenic lipids
<p>The hydrogen isotopic composition (δ2H) of plant compounds is increasingly used as a hydro-climatic proxy, however, the interpretation of δ2H values is hampered by potential co-effecting biochemical and biophysical processes. Here, we studied δ2H values of water and carbohydrates in leaves and roots, and of leaf n-alkanes, in two distinct tobacco (Nicotiana sylvestris) experiments. Large differences in plant performance and biochemistry resulted from (a) soil fertilization with varying nitrogen (N) species ratios and (b) knockout-induced starch deficiency. We observed a strong 2H-enrichment in sugars and starch with a decreasing performance induced by increasing NO3-/NH4+ ratios and starch deficiency, and from leaves to roots. However, δ2H values of cellulose and n-alkanes were less affected. We show that relative concentrations of sugars and starch, interlinked with leaf gas-exchange, shape δ2H values of carbohydrates. We thus provide novel insights into drivers of hydrogen isotopic composition of plant compounds and the mechanistic modelling of plant cellulose δ2H values.</p>
Nitrogen in the Orgueil meteorite: abundant ammonium among other reservoirs of variable isotopic compositions
<p>These data are relative to the paper</p> <p>"Nitrogen in the Orgueil meteorite: abundant ammonium among other reservoirs of variable isotopic compositions"</p> <p>The dataset consists in 20 Excel files that represent the data presented in the Figures and Tables of this paper.</p> <p>Note:</p> <ul> <li>Data from Table S5 of the paper were obtained from the data shown in Table S1, whose data file is provided here</li> <li>Data from Table S6 of the paper were obtained from the data shown in Figure S5, whose data file is provided here</li> </ul>
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Allen Brain Atlas
Allen Brain Atlas is an Allen Institute collection of brain map atlases, datasets, APIs, and analysis tools covering mouse, human, and non-human primate brain resources.
Annotated Behaviour and Observability Dataset (ABODe)
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DANDI Archive for NWB datasets
DANDI is a BRAIN Initiative archive for publishing and sharing neurophysiology data, including electrophysiology, optophysiology, and behavioral data packaged as NWB and related standards.
International Brain Laboratory public data
The International Brain Laboratory public data releases expose standardized mouse decision-making experiments, including Neuropixels recordings, widefield calcium imaging, behavior, and session metadata accessed through the ONE API.
OpenNeuro
OpenNeuro is a free, open platform for sharing neuroimaging datasets, with public search, dataset pages, and download paths for web, S3, DataLad, and the OpenNeuro CLI.