Bibliografie tematiche / Carbon isotope composition

Letteratura scientifica selezionata sul tema "Carbon isotope composition"

Autore: Grafiati

Pubblicato: 8 giugno 2024

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Articoli di riviste sul tema "Carbon isotope composition":

Swart, Peter K., e Jim J. Leder. "The utility of stable isotopic signatures in coral skeletons". Paleontological Society Papers 1 (ottobre 1996): 249–91. http://dx.doi.org/10.1017/s1089332600000127.

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There is a fundamental ecologic differentiation between zooxanthellate and non-zooxanthellate corals. This paper reviews factors which govern the stable carbon and oxygen isotopic composition of these groups of corals. Although the stable carbon and oxygen isotope compositions of coral skeletons are strongly influenced by environmental and physiological factors, the precise mechanisms remain a matter of debate. In particular the oxygen isotopic composition is known to be governed by the temperature and the oxygen isotopic composition of the water and perhaps also by kinetic factors. In contrast the carbon isotopic composition is controlled by a combination of photosynthesis, respiration, autotrophy, heterotrophy, and the isotopic composition of dissolved inorganic carbon. Using a combination of carbon and oxygen isotopes it is possible to distinguish zooxanthellate from non-zooxanthellate corals.

Sare, David T. J., John S. Millar e Frederick J. Longstaffe. "Tracing dietary protein in red-backed voles (Clethrionomys gapperi) using stable isotopes of nitrogen and carbon". Canadian Journal of Zoology 83, n. 5 (1 maggio 2005): 717–25. http://dx.doi.org/10.1139/z05-064.

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We examined the stable isotopes of nitrogen and carbon in a small mammal, the red-backed vole (Clethroinomys gapperi (Vigors, 1830)), to determine if isotope signatures reflect diet composition. Nitrogen- and carbon-isotope ratios in tissues from voles maintained on different protein levels in the laboratory were compared with wild-trapped voles. The isotopic fractionation of dietary nitrogen and carbon was also examined as food was digested in the stomach, incorporated into bone collagen, bioapatite, and hair, and excreted as feces. Nitrogen and carbon isotopes were fractionated differently depending on the isotopic composition and protein content of the diet. δ15N and δ13C values appear to be influenced by factors in addition to diet, such as macronutrients metabolized for respiration, metabolic rate, and periods of protein shortage.

Gruzdev, D. A., A. V. Zhuravlev, Ya A. Vevel, A. V. Erofeevsky e I. V. Smoleva. "Famennian negative carbon isotope excursion in the Izyayu River section (Tchernyshev Uplift, Cis-Uralian Foredeep)". LITHOSPHERE (Russia) 23, n. 2 (27 aprile 2023): 165–78. http://dx.doi.org/10.24930/1681-9004-2023-23-2-165-178.

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Research subject. The article is focused on manifestations of the Early-Middle Famennian negative excursion in carbon isotope composition in the Izyayu River section (south of the Tchernyshev Uplift). Aim. The study is aimed to reconstructing of the probable causes of this isotope excursion. Materials and methods. The article is based on the results of study of the deep-shelf lower-middle Famennian sequence of the Izyayu River section. The carbon isotopic composition was studied for the carbonate samples and conodont elements (32 and 9 samples respectively). Results. The lightening of the carbon isotopic composition of carbonates by 2.5 %, and of the carbon isotopic composition of conodont elements by 4 % were found in the Pal. gracilis gracilis–Pal. marginifera marginifera zonal interval. The difference between the carbon isotopic compositions of carbonates and conodont elements increases in this interval by more than 2.5 %. Possible reasons for the observed variations could be the intensification of terrigenous runoff due to regression, a relatively high content of carbon dioxide in the atmosphere, and, possibly, a local decline in primary bioproductivity. Conclusions. The negative carbon isotope shift spans Pal. gracilis gracilis–Pal. marginifera marginifera zonal interval in the Izyayu River section. The shift corresponds to the global decreasing in the δ13Ccarb values in the early/middle Famennian boundary interval. The increase in supply of the isotopically light carbon with terrigenous runoff and decrease in the primary bioproductivity are considered as probable causes of the carbon isotope excursion.

Zhuravlev, A. V., e I. V. Smoleva. "Preliminary results of studying the carbon isotope composition of conodont elements at the border of Devonian and Carboniferous periods (Kamenka river sections, Pechora carbonate platform)". LITHOSPHERE (Russia) 20, n. 6 (29 dicembre 2020): 829–41. http://dx.doi.org/10.24930/1681-9004-2020-20-6-829-841.

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Research subject. Changes in the trophic structure of shallow-water pelagic ecosystems at the Devonian/Carboniferous border were investigated by studying the carbon isotope composition of conodont organic matter.Materials and methods. Two Devonian-Carboniferous shallow-water clayey-carbonate sections located in the southern part of the Pechora-Kozhva Uplift (Pechora Plate) were analysed. The Devonian-Carboniferous boundary was detected by the first occurrences of Siphonodella sulcata, S. semichatovae and Patrognathus crassus, as well as by the last occurrence of Pseudopolygnathus graulichi. The carbon isotope composition was investigated both in whole-rock carbonate samples and the conodont organic matter of two dominant species (Polygnathus parapetus and P. communis communis).Results. The distribution of stable carbon isotopes in the organic matter of conodont elements accompanied by the data on carbonate isotope composition allowed us to suggest changes in the food composition of the dominant taxa during the Late Famennian-Early Tournaisian transition. It was assumed that the latest Famennian representatives of Polygnathus parapetus and P. communis communis consumed largely phyto- and zooplankton, which is characterized by a light isotopic composition of organic carbon. The nutrition based on phyto- and zooplankton with a heavier isotopic composition of organic carbon was suggested for the early Tournaisian representatives of these species.Conclusions. The discovered variations in the carbon isotope composition of conodont organic matter in shallow-water facies may correspond to the change from the eutrophic pelagic ecosystem to the oligotrophic ecosystem, and/or global perturbation of the carbon cycle due to climatic changes. Since the available data is limited to two geological sections, it is impossible to unambiguously interpret the scale (local, regional, global) of these variations and their correlation potential.

Passey, Benjamin H. "Reconstructing Terrestrial Environments Using Stable Isotopes in Fossil Teeth and Paleosol Carbonates". Paleontological Society Papers 18 (novembre 2012): 167–94. http://dx.doi.org/10.1017/s1089332600002606.

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Carbon isotopes in Neogene-age fossil teeth and paleosol carbonates are commonly interpreted in the context of past distributions of C3 and C4 vegetation. These two plant types have very different distributions in relation to climate and ecology, and provide a robust basis for reconstructing terrestrial paleoclimates and paleoenvironments during the Neogene. Carbon isotopes in pre-Neogene fossil teeth are usually interpreted in the context of changes in the δ13C value of atmospheric CO2, and variable climate-dependent carbon-isotope discrimination in C3 plants. Carbon isotopes in pre-Neogene soil carbonates can be used to estimate past levels of atmospheric CO2. Oxygen isotopes in fossil teeth and paleosol carbonates primarily are influenced by the oxygen isotopic compositions of ancient rainfall and surface waters. The oxygen isotopic composition of rainfall is has a complex, but tractable, relationship with climate, and variably relates to temperature, elevation, precipitation amount, and other factors. Mammal species that rely on moisture in dietary plant tissues to satisfy their water requirements (rather than surface drinking water) may have oxygen isotopic compositions that track aridity. Thus, oxygen isotopes of fossil mammals can place broad constraints on paleoaridity. Carbonate clumped isotope thermometry allows for reconstruction of soil temperatures at the time of pedogenic carbonate mineralization. The method is unique because it is the only thermodynamically based isotopic paleothermometer that does not require assumptions about the isotopic composition of the fluid in which the archive mineral formed. Soil temperature reflects a complex interplay of air temperature, solar radiative heating, latent heat effects, soil thermal diffusivity, and seasonal variations of these parameters. Because plants and most animals live in and/or near the soil, soil temperature is an important aspect of terrestrial (paleo)climate.

Irei, Satoshi. "Isotopic Characterization of Gaseous Mercury and Particulate Water-Soluble Organic Carbon Emitted from Open Grass Field Burning in Aso, Japan". Applied Sciences 12, n. 1 (23 dicembre 2021): 109. http://dx.doi.org/10.3390/app12010109.

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Biomass burning is one of the major emitters of airborne particulate matter (PM) and gaseous mercury. In order to apply the isotopic fingerprinting method to process identification and source apportionment studies, isotopic characterizations of targeted substances at emission are indispensable. Here, we report the stable isotopic composition of total gaseous mercury (TGM) and the stable and radiocarbon isotopic composition of low-volatile water-soluble nitrogen (LV-WSN) and organic carbon (LV-WSOC) in PM emitted from open grass field burning in the Aso region of Japan. The measurement results showed that TGM concentrations in the air increased during the open field burning events, indicating the presence of TGM emissions. The results of LV-WSN analysis showed very low concentrations; therefore, the stable nitrogen isotope ratios could not be measured. The stable mercury isotope ratios exhibited lighter composition than those observed during non-biomass-burning days. The analysis of LV-WSOC revealed heavy stable carbon isotope ratios (average ± SD, −18 ± 2‰), suggesting a substantial contribution from C4 plant carbon. The 14C analysis showed that more than 98% of the LV-WSOC was modern carbon, indicating the contribution of plant carbon to PM emitted from biomass burning. The findings here provide reference isotope compositions of TGM and particulate LV-WSOC from biomass burning in this region.

Evans, JR, TD Sharkey, JA Berry e GD Farquhar. "Carbon Isotope Discrimination measured Concurrently with Gas Exchange to Investigate CO2 Diffusion in Leaves of Higher Plants". Functional Plant Biology 13, n. 2 (1986): 281. http://dx.doi.org/10.1071/pp9860281.

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Conventional gas-exchange techniques that measure the stomatal conductance and rate of CO2 assimilation of leaves were combined with measurements of the carbon isotope composition of CO2 in air passing over a leaf. Isotopic discrimination during uptake was determined from the difference in the carbon isotope composition of air entering and leaving the leaf chamber. Isotopic discrimination measured over the short term correlated strongly with that determined from combusted leaf material. Environmental conditions were manipulated to alter the relative influences of stomatal conductance and carboxylation on the discrimination of carbon isotopes by intact leaves. With C3 plants, discrimination increased as the gradient in partial pressure of CO2 across the stomata decreased. For C4 plants there was little change in discrimination despite substantial changes in the diffusion gradient across the sto- mata. These results are consistent with, and provide the first direct experimental support for, theoretical equations describing discrimination during photosynthesis. Despite uncertainties about various processes affecting carbon isotope composition, the resistance to the transfer of CO2 from the intercellular airspaces to the sites of carboxylation in the mesophyll chloroplasts was estimated using this technique. For wheat the estimated resistance was 1.2-2.4 m2 s bar mol -1.

Kennedy, Brenda V., e H. Roy Krouse. "Isotope fractionation by plants and animals: implications for nutrition research". Canadian Journal of Physiology and Pharmacology 68, n. 7 (1 luglio 1990): 960–72. http://dx.doi.org/10.1139/y90-146.

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The isotopic compositions of animal tissues, minerals, and fluids reflect those of ingested food and water and inhaled gases. This relationship is illustrated by a review of data pertaining to five light elements of biological interest (carbon, nitrogen, hydrogen, oxygen, and sulphur). Processes affecting the isotopic composition of inorganic compounds in reservoirs are summarized, and isotope fractionation during transfer of elements from these inorganic reservoirs through progressive trophic levels of food webs is discussed. Variability of δ values within and among individuals, populations, and species of plants and animals is attributed to at least six factors: locality, dietary selectivity, biochemical composition of food, isotope effects in metabolic processes, turnover rates, and stress. Features of a variety of terrestrial and aquatic ecosystems are used to illustrate basic concepts. Future research should seek to clarify specific mechanisms affecting δ values during the transfer of elements through food webs.Key words: food webs, stable isotopes, isotope fractionation, ecosystems.

Benbow, Timothy J., Alan R. Hayman, Robert Van Hale e Russell Frew. "Preparation of aqueous fatty acids for hydrogen and carbon stable isotope analysis by solid phase extraction". Marine and Freshwater Research 64, n. 4 (2013): 294. http://dx.doi.org/10.1071/mf12192.

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Stable isotope analyses of fatty acids in environmental waters provides important information as to their source(s). Analysis is often confounded due to low concentrations of fatty acids and/or a complex sample matrix requiring separation of the target analyte. The purpose of this study was to validate a method to extract fatty acids from natural waters using solid phase extraction (SPE) before compound specific isotope analysis (CSIA). Three SPE cartridges and multiple eluting solvents were tested to determine the efficiency, isotopic fractionation, and reproducibility of each extraction technique. Our results indicated that surface-modified styrene divinylbenzene cartridges, when eluted with methanol, caused negligible fractionation of the hydrogen isotopes and minimal fractionation of the carbon isotopes, but that isotopic fractionation occurred when compounds were only partially eluted from SPE cartridges. Compounds were also extracted from landfill leachate using both SPE and liquid–liquid extraction (LLE). The hydrogen isotope composition (δ2H) of compounds extracted from water using either method were within experimental precision and the carbon isotope composition (δ13C) of all but one fatty acid were within experimental precision. Therefore, these experiments prove the aforementioned SPE methods to be a convenient and precise method to extract fatty acids from natural waters before CSIA.

Smith, J. J., J. S. Millar, F. J. Longstaffe e R. Boonstra. "The effect of metabolic rate on stable carbon and nitrogen isotope compositions in deer mice, Peromyscus maniculatus". Canadian Journal of Zoology 88, n. 1 (gennaio 2010): 36–42. http://dx.doi.org/10.1139/z09-116.

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The stable isotopic compositions of nitrogen and carbon in animal tissues reflect diet. However, factors other than diet can also affect these stable isotope ratios, leading to misinterpretations of diet composition. To test the hypothesis that variation in metabolic rate alters the isotopic compositions of tissues, deer mice ( Peromyscus maniculatus (Wagner, 1845)) were kept at three temperatures (thermoneutral (23 °C), cool (5 °C), and cold (–10 °C)) and fed ad libitum. The changes in carbon and nitrogen isotope compositions of liver associated with the thermoneutral versus cool and cold conditions were very small in comparison with those arising from differences in diet. We conclude that temperature-induced variations in metabolic rate are insufficient to produce differences in the stable carbon or nitrogen isotope compositions that could be mistaken for changes in diet.

Più fonti

Tesi sul tema "Carbon isotope composition":

Barral, Cuesta Abel. "The carbon isotope composition of the fossil conifer Frenelopsis as a proxy for reconstructing Cretaceous atmospheric CO2". Thesis, Lyon, 2016. http://www.theses.fr/2016LYSE1148.

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Le Crétacé a été une période d'instabilité climatique et du cycle du carbone, dont le CO2 atmosphérique a été désigné comme le driver majeur. Cependant, les reconstitutions du CO2 atmosphérique ne reflètent ni les dynamiques climatiques ni les grands évènements de perturbation du cycle du carbone décrits pour cette période. J'ai utilisé la composition isotopique de carbone de la plante fossile Frenelopsis (d13Cleaf) comme un nouvel proxy pour reconstituer le CO2 atmosphérique du Crétacé en termes de composition isotopique de carbone (d13CCO2) et de concentration (pCO2). La première courbe de d13CCO2 pour toute la durée du Crétacé a été construite à partir du d13C des carbonates marins. Sa comparaison avec des estimations de d13CCO2 à partir du d13Cleaf a révélé que les modèles développés jusqu'à maintenant ont une tendance à exagérer les valeurs de d13CCO2. Des estimations du fractionnement isotopique du carbone issu par des plantes (13Cleaf) obtenues à partir des nouvelles données d e d13Cleaf et d13CCO2 ont permis de reconstituer l'évolution à grande échelle de la pCO2. Ces résultats indiquent que le CO2 a probablement été une conséquence à long terme du changement climatique durant le Crétacé. Des cycles de d13CCO2 de ~1.2, ~2.1, ~5.4 et ~10.2 Ma ont été détectés, synchrones à ceux du niveau de la mer et à la cyclicité des paramètres de l'orbite terrestre décrits pour le Mésozoïque. Mes résultats fournissent une nouvelle perspective du système climatique et du cycle du carbone du Crétacé, dominés principalement par les paramètres orbitaux de la Terre et secondairement par des évènements catastrophiques de libération de CO2 d'origine volcanique dans l'atmosphère
The Cretaceous was a period characterized by strongly marked climate change and major carbon cycle instability. Atmospheric CO2 has repeatedly been pointed out as a major agent involved in these changing conditions during the period. However, long-term trends in CO2 described for the Cretaceous are not consistent with those of temperature and the large disturbance events of the carbon cycle described for the period. This raises a double question of whether descriptions of the long-term evolution of atmospheric CO2 made so far are accurate or, if so, atmospheric CO2 was actually a major driver of carbon cycle and climate dynamics as usually stated. In this thesis the close relationship between the carbon isotope composition of plants and atmospheric CO2 is used to address this question. Based on its ecological significance, distribution, morphological features and its excellent preservation, the fossil conifer genus Frenelopsis is proposed as a new plant proxy for climate reconstructions during the Cretaceous. The capacity of carbon isotope compositions of Frenelopsis leaves (d13Cleaf) to reconstruct past atmospheric CO2, with regards to both carbon isotope composition (d13CCO2) and concentration (pCO2), is tested based on materials coming from twelve Cretaceous episodes. To provide a framework to test the capacity of d13Cleaf to reconstruct d13CCO2 and allowing for climate estimates from carbon isotope discrimination by plants (?13Cleaf), a new d13CCO2 curve for the Cretaceous based on carbon isotope compositions of marine carbonates has been constructed. Comparison with d13Cleaf-based d13CCO2 estimates reveals that although d13CCO2 and d13Cleaf values follow consistent trends, models developed so far to estimate d13CCO2 from d13Cleaf tend to exaggerate d13CCO2 trends because of assuming a linear relationship between both values. However, given the hyperbolic relationship between ?13Cleaf and pCO2, by considering an independently-estimated correction factor for pCO2 for a given episode, d13Cleaf values may be a valuable proxy for d13CCO2 reconstructions. ?13Cleaf estimates obtained from d13CCO2 and d13Cleaf values were used to reconstruct the long-term evolution of pCO2. The magnitude of estimated pCO2 values is in accordance with that of the most recent and relevant model- and proxy-based pCO2 reconstructions. However, these new results evidence long-term drawdowns of pCO2 for Cretaceous time intervals in which temperature maxima have been described

Gromov, Sergey S. [Verfasser]. "Stable isotope composition of atmospheric carbon monoxide : a modelling study / Sergey S. Gromov". Mainz : Universitätsbibliothek Mainz, 2014. http://d-nb.info/1051305497/34.

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Czuba, Eva. "Development of a technique to study stable carbon isotope composition of NMHCs in ambient air". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape2/PQDD_0020/MQ56169.pdf.

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Upsdell, Brynn. "The carbon and nitrogen composition of suspended particulate matter in Lake Erie, selected tributaries, and its outflow". Thesis, University of Waterloo, 2005. http://hdl.handle.net/10012/1219.

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Since their introduction to Lake Erie, dreissenid mussels may have reengineered the cycling of nutrients in the lake so that the nearshore benthic community intercepts, retains, and recycles greater quantities of nutrients. This study traces particulate matter on a basin scale by characterizing the chemical composition (POC and PN concentrations, POC/PN mass ratios, δ¹³C and δ¹⁵N) of suspended particulate matter in Lake Erie, three tributary inflows, and the lake outflow between May and October, 2002. The data are used to 1) determine the relative contributions of allochthonous and autochthonous sources to suspended particulate matter, 2) identify possible sources of suspended particulate matter, and 3) compare suspended particulate matter in the eastern basin of Lake Erie with that in the central and western basins. Mean POC concentrations range from 175 to 4494 µg/L and mean PN concentrations range from 33 to 812 µg/L in this system. Mean POC/PN mass ratios are similar across all sampling locations, ranging between 4. 5 and 6. 9, and indicate that suspended particulate matter at these sites is mainly derived from autochthonous sources, particularly plankton. The ranges of δ¹³C (-34 to -22 ?) and δ¹⁵N (1 to 12 ?) identify terrestrial plants and soil matter, aquatic macrophytes, phytoplankton, and sewage as possible sources of suspended particulate matter at all sites. Plankton is probably the dominant source of suspended particulate matter at each site, with smaller contributions from allochthonous and other autochthonous sources. Significant differences in the concentration and isotope data between inflow and lake or outflow sites indicate that tributary inflows may receive greater contributions from terrestrial plants and soils and aquatic macrophytes than the lake and outflow. δ¹⁵N signatures also identify animal manure as a possible source of suspended particulate matter at the inflows. PN concentrations and δ¹⁵N signatures suggest that the shallowest nearshore sites close to Peacock Point in the eastern basin receive PN from a source that is not present at the other eastern basin sites or at the sites in the central and western basins. This source may be related to dreissenid mussels at these nearshore sites recycling nitrogen back into the water column.

Hamilton, Bryan T. "Small Mammals in portions of Great Basin National Park Susceptible to Groundwater Withdrawal: Diversity and Stable Isotope Perspectives". BYU ScholarsArchive, 2009. https://scholarsarchive.byu.edu/etd/1705.

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To support population growth in Las Vegas, Nevada, large scale increases in groundwater pumping are planned across the state. This pumping could affect riparian areas in Great Basin National Park by lowering groundwater levels, reducing stream flows, and xerifying riparian vegetation. Great Basin National Park (GBNP) is mandated to manage its resources unimpaired for future generations. Loss of biodiversity is unacceptable under this mandate. If groundwater levels are reduced beyond a threshold, aquatic and riparian diversity would be lost, but the effects on small mammal communities are less clear. To provide baseline information and to consider the effects of groundwater withdrawal a priori, we sampled and compared small mammal communities in two watersheds susceptible to groundwater withdrawal and one non-susceptible watershed. We also used to stable isotopes of nitrogen, carbon, deuterium and oxygen to characterize small mammal communities. Evenness was higher in susceptible watersheds, which were distinct in species composition. Riparian and upland habitats in susceptible watersheds supported complementary small mammal communities, while communities in the non-susceptible watershed were more homogenous. Susceptible watersheds are located at the lowest elevations of GBNP where habitat heterogeneity due to the contrast between mesic riparian and xeric upland habitats is important in maintaining small mammal diversity. Partitioning was primarily seen in nitrogen and carbon isotopes which reflect feeding ecology (trophic level and primary production source), but was also seen in oxygen isotopes. Major differences in nitrogen and carbon isotopes were between taxonomic groups, while similarity was highest within these groups. Shrews and ermine were highest in nitrogen reflecting their high trophic positions. Harvest and piñon mice were intermediate in nitrogen suggesting omnivory, while chipmunks, voles, woodrats and pocket mice were apparently herbivorous. Carbon ratios were consistent with C3 based diets but were relatively enriched in Sigmodontinae species. Small mammal deuterium was similar to stream water suggesting that stream water is an important water source of water to small mammals. Oxygen enrichment relative to stream water and precipitation suggested that small mammals are sensitive to body water evaporation. Contrary to a previous study, oxygen isotopes were inversely related to water use efficiency. Increases in the rate of groundwater pumping adjacent to Great Basin National Park could lower water tables, reduce stream flows, and xerify riparian vegetation. We suggest that groundwater levels, streams flow and riparian vegetation, in addition to small mammal species composition will be important response variables in monitoring the effects of groundwater withdrawal. If predictions of groundwater withdrawal are realized, groundwater levels, stream flows, vegetation, microclimate, and invertebrates riparian dependent as well as small mammals will be negatively affected resulting in a decrease in diversity and loss of riparian species from affected areas.

Xia, Yang. "Impact of varying NH₄⁺˸NO₃⁻ ratios in nutrient solution on C-isotope composition of leaf- and root-respired CO₂ and putative respiratory substrates in C₃ plants". Thesis, Université Paris-Saclay (ComUE), 2019. http://www.theses.fr/2019SACLS222.

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La composition isotopique (¹³C/¹²C) du CO₂ respiré par les feuilles et les racines dans l'obscurité et celle des substrats respiratoires putatifs, y compris les sucres solubles et les acides organiques (malate et citrate), l'activité de la PEPc ainsi que les échanges gazeux des feuilles ont été déterminés sur le haricot (Phaseolus vulgaris L.) et l’épinards (Spinacia oleracea L.) cultivés dans du sable avec différents rapports NH₄⁺: NO₃⁻ dans N fourni. Le CO₂ respiré par les feuilles était enrichi en ¹³C sous NO₃⁻ s’appauvrissant progressivement avec l’augmentation de la fraction de NH₄⁺ dans le N fourni, tandis que la composition isotopique du CO₂ issu de la respiration des racines restait inchangée quel que soit le rapport NH₄⁺: NO₃⁻. Nous avons suggéré qu'une plus grande quantité de pools enrichis en ¹³C fixés par la PEPc via la voie anaplérotique contribuait à la respiration foliaire sous NO₃⁻. Cependant, un effet similaire dans les racines attendu sous NH₄⁺ a été masqué en raison d'une refixation (par la PEPc) du CO₂ respiré (appauvrie en ¹³C). De manière inattendue, les modifications de la composition isotopique du C des métabolites individuels, leurs quantités, ainsi que l'activité de l’enzyme PEPc, présentaient des profils différents entre les deux espèces étudiées. Des expériences de double marquage (¹³C et ¹⁵N) sont nécessaires pour mieux comprendre l’impact de la plasticité métabolique du TCA sur l’écart isotopique entre le malate et le citrate et sur la composition isotopique du CO₂ respiré chez différentes espèces sous différentes formes d’azote
C-isotope composition of leaf- and root-respired CO₂ in the dark and that of putative respiratory substrates including soluble sugars and organic acids (malate and citrate), PEPc activity, as well as leaf gas exchanges were determined on bean (Phaseolus vulgaris L.) and spinach (Spinacia oleracea L.) plants grown in sand with varying ratios of NH₄⁺: NO₃⁻ in supplied N. Leaf-respired CO₂ was ¹³C enriched under NO₃⁻ nutrition and became progressively ¹³C depleted with increasing amount of NH₄⁺ in supplied N, while C-isotope composition of root-respired CO₂ remained unchanged across N-type gradient. We suggested that a higher amount of ¹³C enriched C-pools fixed by PEPc through anaplerotic pathway contributed to respired CO₂ in leaves under NO₃⁻ nutrition. However, a similar effect in roots expected under NH4+ nutrition was masked because of a rather ¹³C depleted C source (respired CO₂) refixation by PEPc. Unexpectedly, the changes in C-isotope composition of individual metabolites and their amounts as well as PEPc activity exhibited different patterns between the two species. Double labelling experiments (¹³C and ¹⁵N) are needed for better understanding the impact of metabolic plasticity of TCA on isotopic gap between malate and citrate and on C-isotope composition of respired CO₂ in different species under varying N-type nutrition

Yang, Chengfan. "Li isotope study of Yangtze River sediments : new constraints on climate, weathering and carbon cycle relationships". Electronic Thesis or Diss., Sorbonne université, 2020. https://accesdistant.sorbonne-universite.fr/login?url=https://theses-intra.sorbonne-universite.fr/2020SORUS433.pdf.

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Au cours de ce travail, j’ai réalisé une série d'études dans le bassin du Changjiang (Yangtze), afin de mieux comprendre l'influence de ces effets.Tout d'abord, l'exploitation du barrage des Trois Gorges (TGD) a modifié la composition géochimique des sédiments en aval. Depuis 2003, les sédiments venant des hauts bassins ont été en grande partie retenus en amont, tandis que les sédiments précédemment déposés dans le bassin moyen-inférieur ont été progressivement remis en suspension. Ces processus expliquent l’évolution géochimique des sédiments exportés vers la mer de Chine. En deuxième partie, une étude systématique démontre que les compositions isotopiques en lithium des phases dissoutes et particulaires se comportent de façon conservative dans la zone de mélange de l'estuaire du Changjiang. Cependant, les phases échangeables ne représentent qu'une faible quantité de Li, ce qui explique son impact négligeable dans cette zone. Troisièmement, Cette étude confirme que dans les grands bassins versants, l'altération chimique peut réagir rapidement à de grandes amplitudes climatiques. Ceci est particulièrement bien illustré, dans la carotte CM97, par la période du Younger Dryas. Depuis 2 000 ans, les δ7Li des argiles s’accentuent clairement par rapport à la période précédente, à cause de l'érosion des sols de plaines induite par l'homme. En résumé, ces résultats apportent de nouveaux éclairages sur l'interprétation des proxys et sur la réponse de l'altération chimique aux variations climatiques, ce qui est essentiel pour mieux quantifier l’impact du l’altération continentale sur les climats passés et futurs de notre planète
In order to better understand the weathering-climate feedback, a series of studies was carried out in the Changjiang (Yangtze) Basin. First, the operation of the Three Gorges Dam (TGD) changed downstream sediment geochemical compositions. Before 2003, large amounts of upstream-derived sediments deposited and experienced further weathering in the mid-lower basin. Since 2003, strong riverbed sediment resuspension changed the roles of the mid-lower reaches from important sinks to major sources of sediments delivered to the sea. As a consequence, an intensified weathering intensity of downstream sediment was observed.Second, dissolved δ7Li exhibit a conservative behavior in the Changjiang Estuary. During the process of SPM transported offshore, weathering product flocculated and deposited, while primary minerals resuspended. The combined effect resulted in the UCC-like SPM δ7Li values. There is a Li isotope fractionation between the dissolved load and exchangeable phase. However, this process shows negligible impact on δ7Li of dissolved load and particulates. Third, weathering response to climate is complex in large river basins. During the Younger Dryas, the positive excursion of clay δ7Li is consistent with enhanced incongruent weathering, in response to temperature cooling. The minor variation of clay δ7Li at 11 – 2 ka likely indicate stable weathering and mile climate variation. Over the last 2 kyr, the fluctuation of clay δ7Li is mostly caused by intensification of human activities. In summary, this thesis sheds new lights on the weathering-climate feedback over geologic past, and provides perspectives on how human activities affect natural processes

Allan, Wendy Lynne. "Variation in the stable carbon isotope composition of needle and annual rings in Pseudotsuga menziesii (Mirb.) Franco and its relation to water use needle nitrogen content and productivity". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1996. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp05/mq21902.pdf.

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Rabarijaona, Arivoara. "L'efficience intrinsèque d'utilisation de l'eau (WUEi) du chêne sessile conditionne-t-elle sa résilience à la sécheresse ?" Electronic Thesis or Diss., Paris, AgroParisTech, 2023. http://www.theses.fr/2023AGPT0016.

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La migration assistée constitue une solution pour adapter les peuplements forestiers face à l'augmentation en intensité et fréquence des sécheresse. Elle nécessite néanmoins l'identification des populations les plus résilientes à la sécheresse, et la caractérisation de leur diversité. L'efficience d'utilisation de l'eau (WUE) est un trait pertinent à évaluer pour ce choix car elle traduit un compromis entre l'assimilation carbonée et la perte d'eau par transpiration. En combinant dendrochronologie et isotopie, cette thèse évalue le rôle de WUE sur les performances de croissance et la résilience à la sécheresse du chêne sessile (Quercus petraea).D'abord, WUE a été comparé entre 16 populations dont les individus, issus de graines provenant de sites répartis sur un large gradient pédoclimatique, ont grandi dans la plantation comparative de Sillegny. Des différences significatives de WUE ont été trouvées entre les populations, mais elles n'étaient pas corrélées avec les conditions pédoclimatiques des sites d'origine. Cependant, les populations de provenance à sols sableux montraient de plus fortes augmentations de WUE en réponse à la sécheresse de 2003 par rapport à 2000, comparées aux populations des provenances sur sols limoneux. Par ailleurs, les arbres ayant une forte WUE avaient eu une croissance élevée lors des années humides uniquement. Quoique ces résultats suggèrent une adaptation du chêne sessile, reflétée par la plasticité de WUE à la sécheresse, les variabilités de WUE intra-populations étaient plus importantes que celles entre populations.Ensuite, la variabilité phénotypique de WUE a été étudiée à l'intérieur de deux populations à conditions pédoclimatiques contrastées, à Blois (humide) et La Harth (sec), où tous les arbres de la placette d'étude ont été échantillonnés. Le lien entre WUE et croissance radiale a été particulièrement examiné. Alors que le contrôle stomatique semblait être le facteur clé dans les variations interannuelles de WUE, ses variations inter-individuelles (intra-annuelle) étaient plutôt pilotées par l'assimilation nette de CO2, fortement impactée par le statut social. Ainsi, les relations intra-annuelles entre WUE et croissance apparaissent plus significatives quand la pression de compétition devient plus forte au sein du peuplement (au stade mature), et quand la lumière devient plus limitante que l'eau (dans un site humide, à Blois).Enfin, l'effet de WUE au stade jeune sur la trajectoire de croissance des arbres a été évalué pour les mêmes sites de Blois et la Harth. À la Harth, les arbres avec un WUE plus élevé au stade jeune sont les plus dominants en 2021, suggérant une sélection en faveur d'un fort WUE dans ce milieu. En revanche, ce n'est pas le cas à Blois, où l'effet de WUE au stade jeune sur le statut social des arbres s'arrête après 60 ans. La réponse des arbres à la sécheresse n'était pas affectée par WUE au stade jeune à Blois et seulement durant les premières décennies à La Harth. Par ailleurs, la plasticité de la WUE à la sécheresse semble moins impliquée dans le processus de sélection, à mesure que les arbres vieillissent et sont exposés à des variations environnementales.WUE est un trait complexe influencé par divers facteurs, notamment la génétique, les conditions micro-environnementales et l'âge des arbres. Étant donné que les variations intra-populations sont plus marquées que les différences entre populations, et que le lien entre WUE et la résilience à la sécheresse est relativement faible, le choix des populations de chêne sessile plus adaptées à la sécheresse ne peut se faire sur la base de WUE uniquement
Assisted migration constitute a possibility to adapt forest ecosystems face to the increase in drought intensity and frequency. However, this strategy requires identification of drought-resistant populations and characterization of the diversity within them. Water use efficiency (WUE) is a key trait to assess for this choice, as it reflects a trade-off between carbon assimilation and water loss through transpiration. By combining dendrochronology and stable isotope analysis, this thesis investigates the effect of WUE on the growth performance and resilience to drought of sessile oak (Quercus petraea).Firstly, WUE was compared among 16 populations whose individuals, from seeds originating from sites along a wide range of pedoclimate gradient, had grown in the common garden Sillegny. Significant differences in WUE were found among these populations, but these differences were not correlated with the pedoclimatic conditions of the sites of origin. However, populations from provenances with sandy soils showed a larger increase in WUE in response to the drought of 2003 (compared to the wet year of 2000) than populations from provenances with silty soils. In addition, trees with higher WUE showed larger radial growth only in wet years. Although these results suggest an adaptation of the sessile oak, reflected by the plasticity of WUE to drought, the variability of WUE within populations was higher compared to the differences among populations.Then, the phenotypic variability of WUE was studied within two populations with contrasting soil and climate conditions, at the Blois (wet) and the Harth (dry) sites. All the trees within each plot were sampled, with a particular focus on the relationship between WUE and radial growth. While stomatal control appeared to be the key factor in inter-annual variations in WUE, the inter-individual (intra-annual) variability in WUE was driven more by net CO2 assimilation, which is strongly affected by tree social status. The intra-annual relationships between WUE and growth appeared more significant as the competition among trees within the stand intensified (particularly when trees become mature), and when light availability became a limiting factor rather than water (in a humid site, at Blois).Finally, the effect of WUE expressed by trees at a young age on growth trajectory was assessed within the Blois and the Harth stands. At the Harth site, trees with higher WUE during their young age were the most dominant in 2021, suggesting selection for higher WUE in dry environment. In contrast, at the Blois site, the effect of WUE at the young age on the social status of the trees ceased after 60 years. The response of trees to drought was not significantly affected by WUE at the young age at the Blois site and only during the first decades at the Harth site. Moreover, the plasticity of WUE to drought might play a diminishing role in the selection process as trees age and were exposed to changing environmental conditions.WUE is a complex trait influenced by multiple factors, including genetics, microenvironmental conditions, and tree age. Given that intra-population variations were more pronounced than differences among populations, and that the relationship between WUE and resilience to drought was tenuous, the selection of drought-adapted sessile oak populations cannot be only based on WUE

Fichtler, Esther [Verfasser], Martin [Akademischer Betreuer] Worbes e Rupert [Akademischer Betreuer] Wimmer. "Ecological information of ring width, stable carbon isotope composition and wood anatomical variables in tropical tree rings - A contribution to dendrochronology in the tropics / Esther Fichtler. Gutachter: Martin Worbes ; Rupert Wimmer. Betreuer: Martin Worbes". Göttingen : Niedersächsische Staats- und Universitätsbibliothek Göttingen, 2012. http://d-nb.info/1042262241/34.

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Libri sul tema "Carbon isotope composition":

Geological Survey (U.S.), a cura di. Sulfur/carbon ratios and sulfur isotope composition of some Cretaceous shales from the western interior of North America. [Reston, Va.?]: Dept. of the Interior, U.S. Geological Survey, 1985.

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Martin, Whalen, e United States. National Aeronautics and Space Administration., a cura di. Carbon and hydrogen isotope composition and ℗£þ́C concentration in methane from sources and from the atmosphere: Implications for a global methane budget. [Washington, DC: National Aeronautics and Space Administration, 1994.

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Martin, Whalen, e United States. National Aeronautics and Space Administration., a cura di. Carbon and hydrogen isotope composition and C concentration in methane from sources and from the atmosphere: Implications for a global methane budget. [Washington, DC: National Aeronautics and Space Administration, 1994.

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Moring, J. Bruce. Polychlorinated biphenyls in aquatic invertebrates and fish and observations about nitrogen and carbon isotope composition in relation to trophic structure and bioaccumulation patterns, Lake Worth and Meandering Road Creek, Fort Worth, Texas, 2007-08. Reston, Va: U.S. Dept. of the Interior, U.S. Geological Survey, 2010.

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Westgate, Timothy David. Compositional and carbon isotopic characteristics of abiogenically derived hydrocarbons at the Kidd Creek Mine, Timmins, Ontario. Ottawa: National Library of Canada, 1998.

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Licari, Laetitia. Ecological preferences of benthic foraminifera in the eastern South Atlantic: Distribution patterns, stable carbon isotopic composition, and paleoceanographic implications = Ökologische Ansprüche benthischer Foraminiferen im östlichen Südatlantik : Faunenverbreituhg, Zusammensetzung stabiler Kohlenstoffisotope und paläozeanographische Bedeutung. Bremerhaven: Alfred-Wegener-Institut für Polar- und Meeresforschung, 2006.

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Ellam, Rob. 3. You are what you eat … plus a few per mil. Oxford University Press, 2016. http://dx.doi.org/10.1093/actrade/9780198723622.003.0003.

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‘You are what you eat … plus a few per mil’ explains delta notation and organic isotopic fractionation. An isotopic balance has to be maintained, so the isotopic fractionation into a mineral crystallizing from a fluid will be balanced by a change in the isotopic composition of the remaining fluid. Carbon, nitrogen, oxygen, and strontium isotope values can be measured through the food chain and in animal and human bones. There is also a geographical oxygen isotope zonation, but this is disrupted by major changes in topography. Isotopic measurements helped in identifying King Richard III’s bones and providing background to the life of the 5,000-year-old ‘Ötzi the Iceman’ found in the Ötztal Alps.

National Aeronautics and Space Administration (NASA) Staff. Carbon and Hydrogen Isotope Composition and C-14 Concentration in Methane from Sources and from the Atmosphere: Implications for a Global Methane Budget. Independently Published, 2018.

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Capitoli di libri sul tema "Carbon isotope composition":

Huston, David L., Robert B. Trumbull, Georges Beaudoin e Trevor Ireland. "Light Stable Isotopes (H, B, C, O and S) in Ore Studies—Methods, Theory, Applications and Uncertainties". In Isotopes in Economic Geology, Metallogenesis and Exploration, 209–44. Cham: Springer International Publishing, 2023. http://dx.doi.org/10.1007/978-3-031-27897-6_8.

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AbstractVariations in the abundances of light stable isotopes, particularly those of hydrogen, boron, carbon, oxygen and sulfur, were essential in developing mineralization models. The data provide constraints on sources of hydrothermal fluids, carbon, boron and sulfur, track interaction of these fluids with the rocks at both the deposit and district scales, and establish processes of ore deposition. In providing such constraints, isotopic data have been integral in developing genetic models for porphyry-epithermal, volcanic-hosted massive sulfide, orogenic gold, sediment-hosted base metal and banded-iron formation-hosted iron ore systems, as discussed here and in other chapters in this book. After providing conventions, definitions and standards used to present stable isotope data, this chapter summarizes analytical methods, both bulk and in situ, discusses processes that fractionate stable isotopes, documents the isotopic characteristics of major fluid and rock reservoirs, and then shows how stable isotope data have been used to better understand ore-forming processes and to provide vectors to ore. Analytical procedures, initially developed in the 1940s for carbon–oxygen analysis of bulk samples of carbonate minerals, have developed so that, for most stable isotopic systems, spots as small as a few tens of μm are routinely analyzed. This precision provides the paragenetic and spatial resolution necessary to answer previously unresolvable genetic questions (and create new questions). Stable isotope fractionation reflects geological and geochemical processes important in ore formation, including: (1) phase changes such as boiling, (2) water–rock interaction, (3) cooling, (4) fluid mixing, (5) devolatilization, and (6) redox reactions, including SO2 disproportionation caused by the cooling of magmatic-hydrothermal fluids and photolytic dissociation in the atmosphere. These processes commonly produce gradients in isotopic data, both in time and in space. These gradients, commonly mappable in space, provide not only evidence of process but also exploration vectors. Stable isotope data can be used to estimate the conditions of alteration or mineralization when data for coexisting minerals are available. These estimates use experimentally- or theoretically-determined fractionation equations to estimate temperatures of mineral formation. If the temperature is known from isotopic or other data (e.g., fluid inclusion data or chemical geothermometers), the isotopic composition of the hydrothermal fluid components can be estimated. If fluid inclusion homogenization and compositional data exist, the pressure and depth of mineralization can be estimated. One of the most common uses of stable isotope data has been to determine, or more correctly delimit, fluid and sulfur sources. Estimates of the isotopic compositions of hydrothermal fluids, in most cases, do not define unequivocal sources, but, rather, eliminate sources. As an example, the field of magmatic fluids largely overlap that of metamorphic fluids in δ18O-δD space, but are significantly different to the fields of meteoric waters and seawater. As such, a meteoric or seawater origin for a fluid source may be resolvable, but a magmatic source cannot be resolved from a metamorphic source. Similarly, although δ34S ~ 0‰ is consistent with a magmatic-hydrothermal sulfur source, the signature can also be produced by leaching of an igneous source. Recent analytical and conceptual advances have enabled gathering of new types of isotopic data and application of these data to resolve new problems in mineral deposit genesis and geosciences in general. Recent developments such as rapid isotopic analysis of geological materials or clumped isotopes will continue to increase the utility of stable isotope data in mineral deposit genesis and metallogeny, and, importantly, for mineral exploration.

Quesnel, Benoît, Christophe Scheffer e Georges Beaudoin. "The Light Stable Isotope (Hydrogen, Boron, Carbon, Nitrogen, Oxygen, Silicon, Sulfur) Composition of Orogenic Gold Deposits". In Isotopes in Economic Geology, Metallogenesis and Exploration, 283–328. Cham: Springer International Publishing, 2023. http://dx.doi.org/10.1007/978-3-031-27897-6_10.

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AbstractOrogenic gold deposits formed in various terranes of most ages since the Paleoarchean and generally consist of quartz veins hosted in shear zones formed at the ductile brittle transition under greenschist to lower amphibolite metamorphic conditions. Vein mineralogy is dominated by quartz with various amounts of silicates, carbonates, phyllosilicates, borates, tungstates, sulfides, and oxides. The isotopic composition of these minerals and fluid inclusions has been investigated since the 1960s to constrain the characteristics of orogenic fluid systems involved in the formation of gold deposits worldwide. This review is based on 8580 stable isotope analyses, including δ18O, δD, δ13C, δ34S δ15N, δ11B, and δ30Si values, from 5478 samples from 558 orogenic gold deposits reported in the literature from 1960 to 2010. This contribution describes the variability of the light stable isotopic systems as function of the minerals, the age of the deposits, their regional setting, and their country rocks. The temperature of isotopic equilibrium of orogenic gold veins is estimated from mineral pairs for oxygen and sulfur isotopes. Based on these temperatures, and on fractionation between mineral and fluid components (H2O, CO2 and H2S), the isotopic composition of fluids is estimated to better constrain the main parameters shared by most of auriferous orogenic fluid systems. Orogenic gold deposits display similar isotopic features through time, suggesting that fluid conditions and sources leading to the formation of orogenic gold deposits did not change significantly from the Archean to the Cenozoic. No consistent secular variations of mineral isotope composition for oxygen (−8.1‰ ≤ δ18O ≤ 33‰, n = 4011), hydrogen (−187‰ ≤ δD ≤ −4‰, n = 246), carbon (−26.7‰ ≤ δ13C ≤ 12.3‰, n = 1179), boron (−21.6‰ ≤ δ11B ≤ 9‰, n = 119), and silicon (−0.5‰ ≤ δ30Si ≤ 0.8‰, n = 33) are documented. Only nitrogen (1.6‰ ≤ δ15N ≤ 23.7‰, n = 258) and sulfide sulfur from deposits hosted in sedimentary rocks (−27.2‰ ≤ δ34S ≤ 25‰, n = 717) display secular variations. For nitrogen, the change in composition is interpreted to record the variation of δ15N values of sediments devolatilized during metamorphism. For sulfur, secular variations reflect incorporation of local sedimentary sulfur of ultimate seawater origin. No significant variation of temperature of vein formation is documented for orogenic gold deposits of different ages. Quartz-silicate, quartz-carbonate and sulfide-sulfide mineral pairs display consistent temperatures of 360 ± 76 °C (1σ; n = 332), in agreement with the more common greenschist facies hostrocks and fluid inclusion microthermometry. Fluid sources for orogenic gold deposits are complex but the isotopic systems (hydrogen, boron, carbon, nitrogen, oxygen, sulfur) are most consistent with contributions from metamorphic fluids released by devolatilization of igneous, volcano-sedimentary and/or sedimentary rocks. The contribution of magmatic water exsolved from magma during crystallization is not a necessary component, even if permissible in specific cases. Isotopic data arrays can be interpreted as the result of fluid mixing between a high T (~550 °C)—high δ18O (~10‰)—low δD (~−60‰) deep-seated (metamorphic) fluid reservoir and a low T (~200 °C)—low δ18O (~2‰)—high δD (~0‰) upper crustal fluid reservoir in a number of orogenic gold deposits. The origin of the upper crustal fluid is most likely sea- or meteoric water filling the host rock porosity, with a long history of water–rock isotope exchange. Mixing of deep-seated and upper crustal fluids also explains the large variation of tourmaline δ11B values from orogenic gold veins. Regional spatial variations of oxygen and hydrogen isotope compositions of deep-seated fluid reservoirs are documented between orogenic gold districts. This is the case for the Val-d’Or (Abitibi), Coolgardie and Kalgoorlie (Yilgarn) where the oxygen isotope composition of the deep-seated fluid end-member is 4‰ lower compared to that from the Timmins, Larder Lake, and Kirkland Lake districts (Abitibi). However, both mixing trends converge towards a common, low δ18O upper crustal fluid end-member. Such variations cannot be related to fluid buffering at the site of deposition and suggest provinciality of the fluid source. The contribution of meteoric water is mainly recorded by fluid inclusions from Mesozoic and Cenozoic age deposits, but micas are not systematically in isotopic equilibrium with fluid inclusions trapped in quartz from the same vein. This suggests late involvement of meteoric water unrelated to deposit formation. Yet, a number of deposits with low δD mica may record infiltration of meteoric water in orogenic gold deposits. Isotope exchange between mineralizing fluid and country rocks is documented for oxygen, carbon, sulfur and silicon isotopes. Large variations (> 10‰) of sulfide δ34S values at the deposit scale are likely related to evolving redox conditions of the mineralizing fluid during reaction with country rocks. Deposits hosted in sedimentary rocks show a shift to higher δ18O values as a result of fluid/rock oxygen exchange with the regional sedimentary country rocks.

Hoefs, J. "The Carbon and Oxygen Isotope Composition of Pancreatic Stones". In Chronic Pancreatitis, 147–52. Berlin, Heidelberg: Springer Berlin Heidelberg, 1990. http://dx.doi.org/10.1007/978-3-642-75319-0_18.

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Kelly, Eugene F., Caroline Yonker e Bruno Marino. "Stable Carbon Isotope Composition of Paleosols: An Application to Holocene". In Climate Change in Continental Isotopic Records, 233–39. Washington, D. C.: American Geophysical Union, 2013. http://dx.doi.org/10.1029/gm078p0233.

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Hornibrook, Edward R. C. "The Stable Carbon Isotope Composition of Methane Produced and Emitted from Northern Peatlands". In Carbon Cycling in Northern Peatlands, 187–203. Washington, D. C.: American Geophysical Union, 2013. http://dx.doi.org/10.1029/2008gm000828.

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Singh, Gyanesh Kumar, Debajyoti Paul, Prashant Rajput e Tarun Gupta. "Stable Carbon Isotope and Bulk Composition of Wintertime Aerosols from Kanpur". In Energy, Environment, and Sustainability, 209–20. Singapore: Springer Singapore, 2017. http://dx.doi.org/10.1007/978-981-10-7332-8_10.

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Rachold, V., e H. W. Hubberten. "Carbon Isotope Composition of Particulate Organic Material in East Siberian Rivers". In Land-Ocean Systems in the Siberian Arctic, 223–38. Berlin, Heidelberg: Springer Berlin Heidelberg, 1999. http://dx.doi.org/10.1007/978-3-642-60134-7_21.

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Pataki, Diane E., James T. Randerson, Wenwen Wang, MaryKay Herzenach e Nancy E. Grulke. "The Carbon Isotope Composition of Plants and Soils as Biomarkers of Pollution". In Isoscapes, 407–23. Dordrecht: Springer Netherlands, 2009. http://dx.doi.org/10.1007/978-90-481-3354-3_19.

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Leng, Melanie J., e Jonathan P. Lewis. "C/N ratios and Carbon Isotope Composition of Organic Matter in Estuarine Environments". In Applications of Paleoenvironmental Techniques in Estuarine Studies, 213–37. Dordrecht: Springer Netherlands, 2017. http://dx.doi.org/10.1007/978-94-024-0990-1_9.

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Sun, Fengmei, Guangyu Shi, Huiwen Wang e Shuming Yang. "Relationship Between Diet and Stable Carbon and Nitrogen Isotope Composition in Beef Tissues". In Proceedings of the 2012 International Conference on Applied Biotechnology (ICAB 2012), 1075–82. Berlin, Heidelberg: Springer Berlin Heidelberg, 2013. http://dx.doi.org/10.1007/978-3-642-37922-2_115.

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Atti di convegni sul tema "Carbon isotope composition":

Almubarak, Zainab, Mohammad Alrowaie, Feng Lu e Ranya Algeer. "Gas Chemical and Carbon Isotope Composition as a Diagnostic Tool for Energy". In SPE Annual Technical Conference and Exhibition. SPE, 2022. http://dx.doi.org/10.2118/209992-ms.

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Abstract As the world is moving toward a low-carbon energy structure, natural gas has become critical in the supply of global energy. The genetic identification of different types of natural gas is important for the assessment of their source and exploration potential. Chemical and carbon isotopic compositions of produced gas are useful tools to assess their origin, thermal maturity, migration and to monitor gas production. In this study, we present different geochemical approaches to assess the origin of the gases and thermal maturity as well as to evaluate the effect of adsorption on shale gas during production. Thirteen gas samples from different conventional reservoirs were analyzed for their isotopic compositions to assess gas origin and thermal maturity. To assess gas production, seven gas samples were collected periodically from the same unconventional shale interval and were analyzed for their isotopic signatures. The results demonstrate that carbon isotopic composition of methane to pentane can be used as fingerprinting tool to identify different sources of gas. The studied gases are all of a thermogenic origin and were generated from Type-II marine source rocks. Mixing of gases generated from different source rocks were observed. The mixed gases are characterized by similar isotopic profiles in methane and ethane and they differ in C3+ hydrocarbons. Thermal maturity trends were identified on the studied samples using the relationship between methane, ethane, and propane isotopes versus the wetness index (total HC/methane concentration). To study the effect of gas adsorption during production, samples produced from the same hydrocarbon source rock were assessed at different time intervals (one-year period of production). The results show small variations between isotope compositions; thus, the impact of adsorption is still uncertain and a longer-term monitoring plan is designed. The results of this study shed insight into using isotope geochemistry as an important diagnostic tool for natural gas exploration and production.

Ahsan, Dr Syed Asif, Reem Ali Mabkhout AlSeiari, Dr Tamer Koksalan e Yatindra Bhushan. "Assessment of Sweep Efficiency and Breakthrough Using CO2, H2O, Carbon and Hydrogen Isotope Composition in a Water Alternating with Gas EOR Project in Onshore Abu Dhabi, UAE". In Abu Dhabi International Petroleum Exhibition & Conference. SPE, 2021. http://dx.doi.org/10.2118/208211-ms.

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Abstract Measuring sweep efficiency and understanding breakthrough are the most important parameters to assess an Enhanced Oil Recovery (EOR) project having Water Alternating with miscible CO2 Gas (WAG) injection. The objective of this study was to use CO2, H2O and isotope compositions to assess sweep efficiency and breakthrough in producer wells in an ADNOC Onshore field in order to take the necessary actions for project optimization (e.g., injector and/or future producer well location optimization). CO2 and H2O compositions, along with their respective carbon and hydrogen isotopes, was integrated with downhole pressure gauge data to evaluate the impact of WAG operation on EOR. It was understood at the start of the project that an isotopically distinct injected CO2, compared to the oil associated CO2, would assist in the evaluation of sweep efficiency and breakthrough. The injected CO2 used in the WAG comes from a steel mill that is isotopically very distinct (i.e., significantly light) from the oil associated CO2. CO2 and H2O are injected periodically in the reservoir through designated injectors distributed over the field. The initially produced oil associated CO2, H2O, carbon and hydrogen isotope values were available as reference to measure the extent of sweep efficiency and breakthrough. Injected H2O and CO2 compositions and their respective hydrogen and carbon isotope values are measured at each injection cycle (so called campaigns). This is then followed by periodic compositional and isotopic measurements of the same components in oil and water producer wells to measure the extent of breakthrough. CO2, H2O composition and carbon and hydrogen isotope measurements in injector and producer wells indicate that the injected CO2 is preferentially breaking through in certain parts of the field. This indicates heterogeneous reservoir quality distribution throughout the field with better reservoir quality (e.g. higher permeability) between injector and producer wells having faster breakthrough. The compositional and isotopic measurements are sensitive enough to register compositional changes in the producer wells relatively faster than assessed by downhole pressure gauges.

Bekker, Andrey, e Logan Magad-Weiss. "Carbon Isotope Composition of Seawater in the Aftermath of the Lomagundi Carbon Isotope Excursion". In Goldschmidt2020. Geochemical Society, 2020. http://dx.doi.org/10.46427/gold2020.158.

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Pyrayev, A. N., e A. A. Maksimova. "ISOTOPIC COMPOSITION OF GROUNDWATER IN OIL AND GAS DEPOSITS IN THE CENTRAL PART OF THE TRANS-URAL MEGAMONOCLISE". In All-Russian Youth Scientific Conference with the Participation of Foreign Scientists Trofimuk Readings - 2021. Novosibirsk State University, 2021. http://dx.doi.org/10.25205/978-5-4437-1251-2-117-120.

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Abstract (sommario):

The article presents the first results of complex isotope-hydrogeochemical studies of reservoir waters of the Upper Jurassic deposits of the central regions of the Zaural megamonoclysis. It was shown that most waters have a narrow distribution of oxygen and hy-drogen isotopes (δD from 103,2 to –85,6 % and δ18O from –15,4 to –12,9 %). Some of them have pronounced excursions on the isotopic composition, which indicates a difference in their genesis: from condensate to mixed with ancient infiltrogenic. The isotopic composition of car-bon of water-dissolved carbon dioxide (δ13СDIC from –41,6 to –16,3 %) indicates its biogenic origin and the possibility of interstratal flows from overlying horizons.

Husseinzadeh, R. "Thermal Maturities Based on Stable Carbon Isotope Composition Gases". In Caspian and Black Sea Geosciences Conference. Netherlands: EAGE Publications BV, 2008. http://dx.doi.org/10.3997/2214-4609.20146144.

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Engel, M. H., S. A. Macko e J. A. Silter. "Carbon isotope composition of individual amino acids in the Murchison meteorite". In Physical orgin of homochirality in life. AIP, 1996. http://dx.doi.org/10.1063/1.51236.

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Goncharov, I., R. Kashapov, S. Fadeeva, A. Litvinova, A. Zherdeva, K. Kozyreva e N. Oblasov. "OILS OF NONMARINE GENESIS WITH AN ABNORMALLY LIGHT ISOTOPE COMPOSITION OF CARBON". In 30th International Meeting on Organic Geochemistry (IMOG 2021). European Association of Geoscientists & Engineers, 2021. http://dx.doi.org/10.3997/2214-4609.202134078.

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Chernykh, A. V., A. N. Pyrayev e F. F. Dultsev. "NEW DATA ON THE ISOTOPIC COMPOSITION OF BRINES OF OIL AND GAS DEPOSITS OF THE SIBERIAN PLATFORM". In All-Russian Youth Scientific Conference with the Participation of Foreign Scientists Trofimuk Readings - 2021. Novosibirsk State University, 2021. http://dx.doi.org/10.25205/978-5-4437-1251-2-121-125.

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The new isotope-geochemical data on the Siberian platform supersaturated brines of a wide stratigraphic range (from Riphean to Ordovician) are presented. There is a wide range of oxygen and hydrogen stable isotope composition in the studied brines: from –133 to –17,5 % for δD and from –17,0 to –2,5 % for δ18O. The δD and δ18O values point on the sedimentation-metamorphic genesis of the brines. The carbon isotope composition of the DIC in brines range from –31 to +12,7 %. It is supposed that DIC has the biogenic (bacterial) origin. The youngest brine DIC has the heaviest carbon isotope composition whereas the oldest brine DIC has the biggest concentration of 12C. The strontium ratios of the studied brines divide them into two groups: with 87Sr/86Sr ratios, close to those of the modern ocean waters, and brines with 87Sr/86Sr values significantly exceeding modern ocean strontium ratios. It is assumed that the burial of the brines of the second group took place in the presence of clastic material of the continental crust, with a high content of radioactive 87Rb.

Chen, Zeya, Jianfa Chen e Caisheng Fei. "The Character and Origin of Abnormal Heavy Carbon Isotope Composition in Sedementary Organic Matter". In 29th International Meeting on Organic Geochemistry. European Association of Geoscientists & Engineers, 2019. http://dx.doi.org/10.3997/2214-4609.201902913.

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Popova, Svetlana, Galina V. Simonova, Valery I. Makarov, Daria A. Kalashnikova, Polina N. Zenkova, Alexander P. Lisitzin e Alexander N. Novigatsky. "Variations of the carbon isotope composition and of organic and elemental carbon concentrations of the North Atlantic aerosols". In XXV International Symposium, Atmospheric and Ocean Optics, Atmospheric Physics, a cura di Gennadii G. Matvienko e Oleg A. Romanovskii. SPIE, 2019. http://dx.doi.org/10.1117/12.2538888.

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Rapporti di organizzazioni sul tema "Carbon isotope composition":

Altabet, M. A. Tracing the Fate of Enhanced Organic Carbon Production during a Southern Ocean Fe Fertilization Experiment using Natural Variations in Carbon and Nitrogen Isotopic Composition. Office of Scientific and Technical Information (OSTI), febbraio 2005. http://dx.doi.org/10.2172/837333.

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Piper, Stephen, e Ralph Keeling. Study of the Role of Terrestrial Processes in the Carbon Cycle Based on Measurements of the Abundance and Isotopic Composition of Atmospheric CO2. Office of Scientific and Technical Information (OSTI), gennaio 2012. http://dx.doi.org/10.2172/1032487.

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Boreham, C. J., L. Wang, J. Sohn, N. Jinadasa, Z. Hong, J. Chen, E. Grosjean e A. Jarrett. Exploring for the Future - NDI Carrara 1 gas geochemistry: molecular composition, carbon and hydrogen isotopes of hydrocarbon gases, and the sources of molecular hydrogen and helium. Geoscience Australia, 2022. http://dx.doi.org/10.11636/record.2022.014.

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Keeling, Ralph. Developing Model Constraints on Northern Extra-Tropical Carbon Cycling Based on measurements of the Abundance and Isotopic Composition of Atmospheric CO₂. Office of Scientific and Technical Information (OSTI), dicembre 2014. http://dx.doi.org/10.2172/1165340.

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