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Móri, Cleusa [UNESP]. "Rastreabilidade de farinhas de origem animal em tecidos de codornas de corte pela técnica dos isótopos estáveis de carbono ('intpot.13C'/'intpot.12C') e nitrogênio ('intpot.15N'/'intpot.14N')." Universidade Estadual Paulista (UNESP), 2007. http://hdl.handle.net/11449/104988.
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Estudos para detecção de subprodutos de origem animal em carne de aves são escassos e, em se tratando de codornas são inexistentes. O trabalho teve por objetivo a detecção de farinha de vísceras de aves (FVA) em dietas de codornas de corte no músculo peitoral quilha e tíbia pela técnica dos isótopos estáveis de carbono (13C/12C) e nitrogênio (15N/14N). Foram utilizadas 64 codornas de corte macho de um dia de idade advindas de granja comercial. As aves foram divididas em sete grupos distintos distribuídos aleatoriamente em relação às dietas experimentais que continham diferentes percentagens de FVA: 0; 1,5; 3,0; 4,5; 6,0; 7,5 e 15. As dietas foram formuladas de forma a serem isoenergéticas, isoprotéicas e isoaminoacídicas. Quatro aves de cada tratamento foram abatidas aos 42 dias de idade para colheita do músculo peitoral (Pectoralis major), quilha e tíbia para posteriormente serem analisadas. Observou-se enriquecimento isotópico de d13C e d15N nos três tecidos analisados. Em codornas de corte com 42 dias de idade, o nível de inclusão de farinha de vísceras de aves detectado compreende o intervalo de 3,0 a 4,5%.
Detection of animal origin by-products studies in poultry meat are rare and inexistent when related to quail meat. This paper aims the detection of increasing levels of poultry visceral meal (FVA) in quail meat, using carbon (13C/12C) and nitrogen (15N/14N) stable isotopes technique. Sixty four male quails aging one day originally from a commercial producer were divided in seven different groups in a random distribution. Those groups received different experimental diets containing 0; 1,5; 3,0; 4,5; 6,0; 7,5 e 15% of FVA. Those diets were formulated to be isoenergetic, isoproteic and to have the same level of amino-acids. Four individuals per treatment were sacrificed at the 42nd day for breast muscle (Pectoralis major), keel and tibia collection to later analysis. Isotopic enrichment of d13C and d15N were observed in all analyzed tissues. In 42 day old quail were detect a 3,0 and 4,5% poultry visceral meal inclusion in its diet.
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Móri, Cleusa 1974. "Rastreabilidade de farinhas de origem animal em tecidos de codornas de corte pela técnica dos isótopos estáveis de carbono ('intpot.13C'/'intpot.12C') e nitrogênio ('intpot.15N'/'intpot.14N') /." Botucatu : [s.n.], 2007. http://hdl.handle.net/11449/104988.
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Orientador: Edivaldo Antônio GarciaBanca: Ricardo de Albuquerque
Banca: Carla Cachoni Pizzolante
Banca: Carlos Ducatti
Banca: Ariel Antonio Mendes
Resumo: Estudos para detecção de subprodutos de origem animal em carne de aves são escassos e, em se tratando de codornas são inexistentes. O trabalho teve por objetivo a detecção de farinha de vísceras de aves (FVA) em dietas de codornas de corte no músculo peitoral quilha e tíbia pela técnica dos isótopos estáveis de carbono (13C/12C) e nitrogênio (15N/14N). Foram utilizadas 64 codornas de corte macho de um dia de idade advindas de granja comercial. As aves foram divididas em sete grupos distintos distribuídos aleatoriamente em relação às dietas experimentais que continham diferentes percentagens de FVA: 0; 1,5; 3,0; 4,5; 6,0; 7,5 e 15. As dietas foram formuladas de forma a serem isoenergéticas, isoprotéicas e isoaminoacídicas. Quatro aves de cada tratamento foram abatidas aos 42 dias de idade para colheita do músculo peitoral (Pectoralis major), quilha e tíbia para posteriormente serem analisadas. Observou-se enriquecimento isotópico de d13C e d15N nos três tecidos analisados. Em codornas de corte com 42 dias de idade, o nível de inclusão de farinha de vísceras de aves detectado compreende o intervalo de 3,0 a 4,5%.
Abstract: Detection of animal origin by-products studies in poultry meat are rare and inexistent when related to quail meat. This paper aims the detection of increasing levels of poultry visceral meal (FVA) in quail meat, using carbon (13C/12C) and nitrogen (15N/14N) stable isotopes technique. Sixty four male quails aging one day originally from a commercial producer were divided in seven different groups in a random distribution. Those groups received different experimental diets containing 0; 1,5; 3,0; 4,5; 6,0; 7,5 e 15% of FVA. Those diets were formulated to be isoenergetic, isoproteic and to have the same level of amino-acids. Four individuals per treatment were sacrificed at the 42nd day for breast muscle (Pectoralis major), keel and tibia collection to later analysis. Isotopic enrichment of d13C and d15N were observed in all analyzed tissues. In 42 day old quail were detect a 3,0 and 4,5% poultry visceral meal inclusion in its diet.
Doutor
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Bordinhon, André Moreira [UNESP]. "Autobalanceamento da energia e da proteína da dieta pela tilápia do Nilo por meio de isótopos estáveis de carbono e do consumo de matéria seca." Universidade Estadual Paulista (UNESP), 2008. http://hdl.handle.net/11449/104115.
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O objetivo deste trabalho foi avaliar a capacidade da tilápia do Nilo em 5 balancear sua dieta, quando fornecidas duas misturas de ingredientes, utilizando os 6 isótopos estáveis de carbono. Foram utilizados 225 juvenis de tilápia (peso: 5,0 ± 0,5 g), 7 distribuídos em cinco tanques. Os indivíduos alocados em um dos tanques eram 8 alimentados com uma mistura de alta proteína (MAP; δ13C = -22,62‰), os alocados em 9 um segundo tanque eram alimentados com uma mistura de baixa proteína (MBP; δ13C = 10 -14,34‰) e os animais dos outros tanques tinham acesso livre a ambas, quatro vezes ao 11 dia. Foram realizadas coletas de músculo, fígado e sangue a cada cinco dias por 86 dias, 12 exceto para o grupo alimentado com MBP (alimentado por 120 dias). As amostras 13 foram analisadas em espectrômetro de massa e as proporções consumidas das misturas 14 foram estimadas a partir do enriquecimento isotópico do carbono (δ13C). O 15 balanceamento realizado indicou redução no consumo relativo de proteína. Contudo, 16 esta relação não apresentou padrão definido em relação ao peso dos indivíduos, ou seja: 17 o balanceamento de proteína e energia para tilápia do Nilo está relacionado 18 principalmente à idade dos animais e não é claro se este processo está relacionado 19 também ao seu peso. As estimativas de consumo de um grupo animais desta espécie por 20 meio dos isótopos estáveis de carbono são semelhantes aos obtidos por outras técnicas, 21 portanto este método permite observação da diversidade deste comportamento no 22 autobalanceamento entre os indivíduos que compõe tal grupo.
This study aimed to assess the Nile tilapia ability to balance its own diet, 6 when two ingredient mixes were offered, using carbon stable isotopes. In order to 7 accomplish that, 225 Nile tilapia juveniles (average initial weight 5.0g ± 0.5g) were 8 distributed in five tanks, each containing a group of 45 fish. One group of fish were fed 9 exclusively a high protein mix (HPM; δ13C = -22.62‰), a second one fed only a low 10 protein mix (LPM; δ13C = -14.34‰). The other groups had free access to both mixes 11 (free choice system). The fish from all tanks were fed four times a day. Muscle, liver 12 and blood samples were collected at each five days (from 2 fish/tank/collection) for 86 13 days, except for the fish fed with MBP (fed for a 120 days period). The samples were 14 analyzed in a mass spectrometer and proportions of the mixes consumed were estimated 15 through its carbon isotope enrichment (δ13C). The fish diminished their protein intake 16 along the time. However, consumption did not present a clear pattern in relation to the 17 individual weight, i.e.: protein consumption patterns are mainly related to the age of the 18 individuals and it is not clear if it is also correlated to their weight. The consumption 19 estimative through stable isotopes of carbon did not conflict other studies reported in the 20 literature. Additionally this technique allowed observation of consumption among the 21 individuals from an experimental group 22.
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Bordinhon, André Moreira 1978. "Autobalanceamento da energia e da proteína da dieta pela tilápia do Nilo por meio de isótopos estáveis de carbono e do consumo de matéria seca /." Botucatu : [s.n.], 2008. http://hdl.handle.net/11449/104115.
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Orientador: Luiz Edivaldo PezzatoBanca: Wilson Massamitu Furuya
Banca: José Fernando Machado Menten
Banca: Carlos Ducatti
Banca: José Roberto Sartori
Resumo: O objetivo deste trabalho foi avaliar a capacidade da tilápia do Nilo em 5 balancear sua dieta, quando fornecidas duas misturas de ingredientes, utilizando os 6 isótopos estáveis de carbono. Foram utilizados 225 juvenis de tilápia (peso: 5,0 ± 0,5 g), 7 distribuídos em cinco tanques. Os indivíduos alocados em um dos tanques eram 8 alimentados com uma mistura de alta proteína (MAP; δ13C = -22,62‰), os alocados em 9 um segundo tanque eram alimentados com uma mistura de baixa proteína (MBP; δ13C = 10 -14,34‰) e os animais dos outros tanques tinham acesso livre a ambas, quatro vezes ao 11 dia. Foram realizadas coletas de músculo, fígado e sangue a cada cinco dias por 86 dias, 12 exceto para o grupo alimentado com MBP (alimentado por 120 dias). As amostras 13 foram analisadas em espectrômetro de massa e as proporções consumidas das misturas 14 foram estimadas a partir do enriquecimento isotópico do carbono (δ13C). O 15 balanceamento realizado indicou redução no consumo relativo de proteína. Contudo, 16 esta relação não apresentou padrão definido em relação ao peso dos indivíduos, ou seja: 17 o balanceamento de proteína e energia para tilápia do Nilo está relacionado 18 principalmente à idade dos animais e não é claro se este processo está relacionado 19 também ao seu peso. As estimativas de consumo de um grupo animais desta espécie por 20 meio dos isótopos estáveis de carbono são semelhantes aos obtidos por outras técnicas, 21 portanto este método permite observação da diversidade deste comportamento no 22 autobalanceamento entre os indivíduos que compõe tal grupo.
Abstract: This study aimed to assess the Nile tilapia ability to balance its own diet, 6 when two ingredient mixes were offered, using carbon stable isotopes. In order to 7 accomplish that, 225 Nile tilapia juveniles (average initial weight 5.0g ± 0.5g) were 8 distributed in five tanks, each containing a group of 45 fish. One group of fish were fed 9 exclusively a high protein mix (HPM; δ13C = -22.62‰), a second one fed only a low 10 protein mix (LPM; δ13C = -14.34‰). The other groups had free access to both mixes 11 (free choice system). The fish from all tanks were fed four times a day. Muscle, liver 12 and blood samples were collected at each five days (from 2 fish/tank/collection) for 86 13 days, except for the fish fed with MBP (fed for a 120 days period). The samples were 14 analyzed in a mass spectrometer and proportions of the mixes consumed were estimated 15 through its carbon isotope enrichment (δ13C). The fish diminished their protein intake 16 along the time. However, consumption did not present a clear pattern in relation to the 17 individual weight, i.e.: protein consumption patterns are mainly related to the age of the 18 individuals and it is not clear if it is also correlated to their weight. The consumption 19 estimative through stable isotopes of carbon did not conflict other studies reported in the 20 literature. Additionally this technique allowed observation of consumption among the 21 individuals from an experimental group 22.
Doutor
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Linebaugh, Donald W. "Carbon cycling in the York River Estuary: an isotopic and mass balance approach using natural Carbon-14 and Carbon-18 isotopes." W&M ScholarWorks, 1999. https://scholarworks.wm.edu/etd/1539791832.
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Österlin, Carl. "STABLE CARBON ISOTOPES IN SPELEOTHEMS FROM TEMPERATE AREAS." Thesis, Stockholms universitet, Institutionen för naturgeografi och kvartärgeologi (INK), 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-55353.
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Speleothems are considered a reliable proxy for paleoclimatic reconstructions and analysis of stable carbon isotopes in speleothems is used for paleoclimatic reconstructions. However, in temperate areas that lacks C4 vegetation there are uncertainties in how to interpret changes in the δ13C signal. The aim of this study is toincrease the understanding of how the δ13C signal in speleothems from temperateareas can be interpreted. The study was divided in two parts, first a literature studythat focused on interpretations of the δ13C signal in speleothems from temperate areasand a case study in which a comparison of seven 13C records from similarenvironments in the Scandes Mountains and the Alps are made. The results from the literature study were used in the case study to draw conclusions on tree line and vegetation changes during Holocene in central northern Scandinavia. The study showed that trends in interpretation of the δ13C signal in speleothems from temperateareas are that low δ13C values are interpreted as wetter, warmer conditions with higherbio productivity, and high δ13C values are interpreted as colder, drier conditions withlower bio productivity. Further it was found in the study that vegetation changes seen in Holocene pollen data are also seen in δ13C records from Scandinavia. The δ13Csignal in temperate speleothems therefore appears to be related to changes invegetation density and to tree-line changes.
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Curtis-Summers, Shirley. "Stable Isotopes of Carbon and Nitrogen and Diet." Society of Antiquaries of Scotland, 2016. http://hdl.handle.net/10454/17856.
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Sadurski, Stephen Edward. "The Biogeochemistry of Carbon Isotopes in Local Lakes." Wright State University / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=wright1357745315.
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Schlanser, Kristen M. "Advancing Leaf Carbon Isotopes as a Paleo Proxy." University of Cincinnati / OhioLINK, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=ucin159584747503534.
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McNichol, Ann P. "A study of remineralization of organic carbon in nearshore sediments using carbon isotopes /." Woods Hole, Mass. : Woods Hole Oceanographic Institution, 1986. http://hdl.handle.net/1912/3228.
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Lo, Tierzo Vivian [UNESP]. "Turnover do carbono nos tecidos de suínos em diferentes fases de crescimento." Universidade Estadual Paulista (UNESP), 2007. http://hdl.handle.net/11449/104053.
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Universidade Estadual Paulista (UNESP)
Este trabalho objetivou determinar o turnover do carbono no sangue, pâncreas e tíbia de suínos em diferentes períodos de crescimento, utilizando a técnica de isótopos estáveis. Foram utilizados 132 machos castrados e fêmeos, distribuídos ao acaso em quatros tratamentos que consistiam da substituição da dieta a base de milho (planta de ciclo fotossintético C4) por dieta a base de arroz (plantas do ciclo fotossintético C3) em dias distintos: 21; 42; 63; 110 dias de idade, respectivamente para os tratamentos 1, 2, 3 e 4. Para mensurar o turnover do carbono (diluição isotópica) nos tecidos em determinado intervalo de tempo, foram utilizados o modelo de equações de função exponencial do tempo ou modelo sigmoidal de regressão de Boltzmann. Os valores de meias-vidas foram: 15,9; 19,0 e 16,8 dias para o sangue; 14,1; 9,68 e 10,4 dias para o pâncreas; 14,3; 8,0 e 15,1 dias para tíbia com medula nos tratamentos com substituição aos 21, 42 e 63 de idade respectivamente. O pâncreas de acordo com valores de meia vida apresentou um rápido turnover, o sangue e a tíbia com medula apresentaram maiores valores de meia vida
This study aimed to determine the turnover of carbon in the blood, tibia and pancreas of pigs at different growth periods, using the technique of stable isotopes. We used 132 barrows and females were randomly assigned into four groups consisting of replacing the corn-based diet (plant C4 photosynthetic cycle) by diet of rice (C3 photosynthetic cycle plants) on different days: 21; 42, 63; 110 days of age, respectively for treatments 1, 2, 3 and 4. To measure the turnover of carbon (isotope dilution) in tissues given time interval, we used the model equations exponential function of time or template Boltzmann sigmoidal regression. Values of half-lives were 15.9, 19.0 and 16.8 days for the blood; 14.1, 9.68 and 10.4 days for the pancreas, 14.3, 8.0 and 15, one day to the tibia with bone replacement treatments at 21, 42 and 63 of age respectively. The pancreas according to half-life values showed a rapid turnover, blood and tibia with bone showed higher half-life
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Archbold, M. E. "Carbon isotopes of volatile organic compounds for environmental tracing." Thesis, Queen's University Belfast, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.419452.
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Crichton, Katherine. "The role of permafrost soils in the global carbon-cycle on the timescales of centuries to multi-millennia : a modelling study." Thesis, Grenoble, 2014. http://www.theses.fr/2014GRENU049/document.
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Cette étude visait à développer un modèle dynamique du pergélisol-carbone à intégrer dans le modèle CLIMBER-2 et d'effectuer des simulations en vue de contribuer à la connaissance du cycle du carbone. Ce travail pourrait, pour la première fois, permettre une étude de modélisation avec un modèle de système terrestre qui comprendrait l'atmosphère dynamique, l'océan dynamique, la végétation dynamique et les composantes de la cryosphere, y compris les terres gelées, afin d'étudier le paléoclimat. La disponibilité des données récentes du CO2 et de δ13C de CO2 dans l'atmosphère fourni un moyen de valider les résultats du modèle pour déterminer si une dynamique pergélisol-carbone pourrait avoir joué un rôle important au cours des climats changeants.Un mécanisme pergélisol-carbone simplifié a été développé et validé et à été réglé en utilisant les données de la terminaison 1 (T1). Il a été constaté que, pour reproduire des données de CO2 et δ13C atmosphériques (pour l'atmosphère et l'océan) au cours de T1, une combinaison des mécanismes océaniques-glaciaires et pergélisol-carbone ont été nécessaires. Suite à cette constatation, plusieurs cycles glaciaires ont été modélisés pour étudier la sensibilité du mécanisme pergélisol-carbone aux forçages de CO2, les calottes glaciaires et l'insolation. l'étendue des calottes glaciaires a été jugée particulièrement importante pour le contrôle de la superficie des terres disponibles pour le pergélisol, et donc aussi pour la dynamique du carbone du pergélisol-carbone. La libération du carbone dans les sols de dégel en réponse à l'augmentation de l'insolation d'été dans les hautes latitudes, a été jugée très probable comme la source des hausses initiales de CO2 dans l'atmosphère au cours des terminaisons glaciaires.Les données CO2 de terminaison 1 peuvent être bien reproduits, y compris le plateau de CO2 BA / YD, quand le forçage de l'eau douce est appliqué à l'Atlantique nord. Expériences avec forçage de l'eau douce ont souligné l'importance du mécanisme du pergélisol-carbone dans l'évolution rapide des climats. Les augmentations très rapides des niveaux de CO2 dans l'atmosphère peuvent être expliqués par la libération rapide des sols en carbone en réponse à l'augmentation du transport de chaleur vers l'hémisphère nord. C'est en réponse à la reprise de l'AMOC suite d'un événement AMOC arrêt/réduction, tels que des événements D/O vu dans les données du δ18O Groenland. Les projections de changement climatique représentent des événements de réchauffement rapide. La conduite du modèle par des projections d'émissions (base de données RCP) a prédit l'augmentation du CO2 de pic et une plus longue période a des niveaux élevées de CO2 par rapport aux sorties du modèle qui ne comprennent pas les évaluations du pergélisol-carbone.L'analyse de δ13C de l'océan doit tenir compte de la dynamique du pergélisol et du carbone de la terre en général et de son effet sur les niveaux de δ13C atmosphériques. Si ce n'est pas pris en compte alors la circulation océanique peut être trop invoquée pour tenter d'expliquer les changements de δ13C de l'océan et du CO2 atmosphérique.Le mécanisme pergélisol-carbone réagit aux changements de température et amplifie la réponse du cycle du carbone. Il est fortement dépendant non seulement de l'apport d'énergie (qui détermine la température du sol et de l'emplacement du pergélisol), mais également de la surface de terres disponible à l'échelle mondiale sur laquelle le pergélisol peut exister. Afin de modéliser et de comprendre correctement la réponse du système terrestre dans les climats futurs et passés, le mécanisme de rétroaction pergélisol-carbone est un élément important du système. Ce travail a été une première étape pour aborder le rôle que la cryosphere terrestre joue dans le cycle du carbone et du système climatique sur de longues échelles de temps, et que d'autres études sont essentiellesThis study aimed to develop a permafrost-carbon dynamic model to incorporate into the CLIMBER-2 Earth system model and to carry out simulations with a view to contributing to the knowledge of the carbon cycle. The work would, for the first time, allow a fully coupled modelling study with an earth system model which included dynamic atmosphere, ocean, vegetation and cryosphere components including frozen land to study paleoclimates. The availability of recent ice core data for CO2 and δ13C of atmospheric CO2 was to provide a means of validating model findings to identify whether a permafrost-carbon dynamic could have played a significant role in past changing climates.The deep Southern Ocean is an area of particular interest for glacial-interglacial CO2 variability, and current modelling efforts aim to recreate the observed CO2 changes using ocean mechanisms. These are often related to deep southern ocean carbon storage and release. So far the terrestrial biosphere has not been well-considered in transient simulations of the carbon cycle in Earth system models.A simplified permafrost-carbon mechanism was developed and validated and tuned using data from termination 1. It was found that in order to reproduce atmospheric CO2 and δ13C data (for atmosphere and ocean) during the termination, a combination of glacial ocean mechanisms and the permafrost-carbon mechanism was required. Following this finding, several glacial cycles were modelled to study the sensitivity of the permafrost-carbon mechanisms to CO2, ice sheets and insolation. Ice sheet extent was found to be particularly important in controlling the land area available for permafrost and therefore the carbon dynamics of permafrost-carbon. The permafrost-carbon mechanism, via carbon release from thawing soils responding to increasing summer insolation in higher northern latitudes, was found to very likely be the source of initial rises in CO2 on glacial terminations.Termination 1 CO2 data could be well reproduced, including the B-A/YD CO2 plateau, when fresh water forcing was applied to the north Atlantic. Fresh water forcing experiments pointed to the importance of the permafrost-carbon mechanism in fast changing climates. Very fast increases in atmospheric CO2 levels may be explained by fast soil-carbon release responding to increased heat transport to the northern hemisphere on AMOC resumption following an AMOC switch-off/reduction event, such as D/O events seen in the Greenland δ18O record. Future climate change projections represent fast warming events. Driving the model by emissions projections (RCP database) predicted increased peak CO2 and much longer term elevated CO2 levels relative to model outputs which did not include the permafrost carbon feedback.Analysis of ocean δ13C must take into account the dynamics of permafrost and land carbon in general and its effect on atmospheric δ13C levels. If this is not taken into account then ocean circulation may be over-invoked in attempting to explain changes in ocean δ13C and atmospheric CO2. The Earth system is not simply atmosphere and ocean. The findings in this work highlight that it is essential to consider land carbon dynamics when interpreting paleo-indicators for the carbon cycle.The permafrost-carbon mechanism reacts to temperature changes and amplifies the carbon cycle's response. It is stongly dependent not only on energy input (that determines soil temperature and permafrost location), but also on the area of land available globally on which it can exist. In order to properly model and understand the Earth system response to forcing in both future and past climates, the permafrost-carbon feedback mechanism is an important system component. This work has been a first step to address the role that the land cryosphere plays in the carbon cycle and climate system on long timescales, and further studies are essential
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McNichol, Ann P. 1956. "A study of the remineralization of organic carbon in nearshore sediments using carbon isotopes." Thesis, Massachusetts Institute of Technology, 1986. http://hdl.handle.net/1721.1/58489.
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Thesis (Ph. D.)--Joint Program in Oceanography (Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences; and the Woods Hole Oceanographic Institution), 1986.Vita.
Includes bibliographical references (leaves 208-215).
A study of the remineralization of organic carbon was conducted in the organic-rich sediments of Buzzards Bay, MA. Major processes affecting the carbon chemistry in sediments are reflected by changes in the stable carbon isotope ratios of dissolved inorganic carbon (XCO2) in sediment pore water. Six cores were collected seasonally over a period of two years. The following species were measured in the pore waters: JC02, &'3 C-2CO2, P04, JH 2S, Alk, DOC, and Ca. Measurements of pore water collected seasonally show large gradients with depth, which are larger in summer than in winter. The 613C (PDB) of IC02 varies from 1.3 o/oo in the bottom water to approximately -10 o/oo at 30 cm. During all seasons, there was a trend towards more negative values with depth in the upper 8 cm due to the remineralization of organic matter. There was a trend toward more positive values below 8 cm, most likely due to biological irrigation of sediments with bottom water. Below 16-20 cm, a negative gradient was re-established which indicates a return to remineralization as the main process affecting pore water chemistry. Using the XC02 depth profile, it was estimated that 67-85 gC/m 2 are oxidized annually and 5 gC/m 2-yr are buried. The amount of carbon oxidized represented remineralization occurring within the sediments. This estimate indicated that approximately 20% of the annual primary productivity reached the sediments. The calculated remineralization rates varied seasonally with the high of 7.5 x 10-' mol/L-sec observed in August 84 and the low (0.6 x 10-) in December 83. The calculated remineralization rates were dependent on the amount of irrigation in the sediments; if the irrigation parameter is known to ±20%, then the remineralization rates are known to this certainty also. The amount of irrigation in the sediments was estimated using the results of a seasonal study of 2 2 2Rn/ 22 'Ra disequilibria at the same study site (Martin, 1985). Estimates of the annual remineralization in the sediments using solid-phase data indicated that the solid-phase profiles were not at steady-state concentrations. The isotopic signature of 2C02 was used as an indicator of the processes affecting IC02 in pore water. During every month, the oxidation of organic carbon to C02 provided over half of the carbon added to the IC02 pool. However, in every month, the 6'"C of XCO2 added to the pore water in the surface sediments was greater than -15 o/oo, significantly greater than the 613C of solid-phase organic carbon in the sediments (-20.6 o/oo). The 613C of IC02 added to the pore water in the sediments deeper than 7 cm was between -20 and -21 o/oo, similar to the organic carbon in the sediments. Possible explanations of the 1 3C-enrichment observed in the surface sediments were: a) significant dissolution of CaC0 3 (613C = +1.7 o/oo) b) the addition of significant amounts of carbonate ion from bottom water to pore water c) an isotopic difference between the carbon oxidized in the sediments and that remaining in the sediments. The effect of CaC0 3 dissolution was quantified using measured dissolved Ca profiles and was not large enough to explain the observed isotopic enrichment. An additional source of 13C-enriched carbon was bottom water carbonate ion. In every month studied, there was a net flux of 2C0 2 from pore water to bottom water. The flux of pore water 2C02 to bottom water ranged from a minimum of 10 x 10-12 mol/cm 2 -sec in December 83 to a maximum of 50 x 10-12 mol/cm2-sec in August 84. However, because the pH of bottom water was about 8 while that of the pore water was less than or equal to 7, the relative proportion of the different species of inorganic carbon (H2CO, HCO-, C0~) was very different in bottom water and pore water. Thus, while there was a net flux of IC0 2 from pore water to bottom water, there was a flux of carbonate ion from bottom water to pore water. Because bottom water JC02 was more 13C-enriched than pore water JC0 2, the transfer of bottom water carbonate ion to pore water was a source of 13C-enriched carbon to the pore water. If the &'3C of CO2 added to the pore water from the oxidation of organic carbon was -20.6 o/oo, then the flux of C3% from bottom water to pore water must have been 10-30% of the total flux of 2C02 from pore water to bottom water. This is consistent with the amount calculated from the observed gradient in carbonate ion. Laboratory experiments were conducted to determine whether the 613C of C02 produced from the oxidation of organic carbon (613C-OCOX) was different from the 613C of organic carbon in the sediments (613C-SOC). In the laboratory experiments, mud from the sampling site was incubated at a constant temperature. Three depths were studied (0-3, 10-15, and 20-25 cm). For the first study (IEl), sediment was stirred to homogenize it before packing into centrifuge tubes for incubation. For the second study (IE2), sediment was introduced directly into glass incubation tubes by subcoring. The second procedure greatly reduced disturbance to the sediment. Rates of C02 production were calculated from the concentrations of 2C02 measured over up to 46 days. In both studies, the values of Re in the deeper intervals were about 10% of the surface values. This was consistent with the field results, although the rates decreased more rapidly in the field. In all cases, the remineralization rates during the beginning of IEl were much greater than those at the beginning of IE2. The sediment for IEl was collected in February 84. The measured value of Rc in the surface sediment of the laboratory experiment (24 x 10- mol/L-sec) was much greater than the value of Rc observed in the field in another winter month, December 83 (.62 x 10~9). The sediment for IE2 was collected in August 85. The measured values of Re in the surface sediment (6.6-12 x 10~9 mol/L-sec) were consistent with the field values from August 84 (7.5 x 10-9). The XC02 results indicated that IE2 reproduced field conditions more accurately than IEl did. The isotopic results from the experiments strongly suggested that 613C-OCOX in the surface sediments (-17.8 o/oo ± 1.9 o/oo) was greater than 6'3C-SOC (-20.6 ± 0.2 o/oo). The magnitude of the observed fractionation was small enough that the observed values of 613C-C02 in the pore waters could be explained by fractionated oxidation coupled with the diffusion of carbonate ion from bottom water to pore water. The observed fractionation was most likely due to the multiple sources of organic carbon to coastal sediments. A study of the natural levels of radiocarbon in these sediments indicated that the carbon preserved in the sediments is approximately 30% terrestrial while the rest is from phytoplankton.
by Ann P. McNichol.
Ph.D.
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Gardner, Adele F. "An organic geochemical study of the Cretaceous/Tertiary boundary." Thesis, Open University, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.321559.
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Eek, Magnus. "Environmental control of stable carbon isotope systematics in Emiliania huxleyi." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape2/PQDD_0017/NQ52759.pdf.
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Gilmour, Iain. "The distribution of carbon stable isotopes within sedimentary organic matter." Thesis, University of Cambridge, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.373660.
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Dixon, Luke Ian. "Introduction of carbon isotopes into organic frameworks using alkynyiodonium salts." Thesis, University of Newcastle Upon Tyne, 2011. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.578554.
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Sweeting, Christopher J. "Carbon and nitrogen stable isotopes as descriptors of fish trophodynamics." Thesis, University of Newcastle Upon Tyne, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.405361.
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Vainonen-Ahlgren, Elizaveta. "Release of hydrogen isotopes from carbon based fusion reactor materials." Helsinki : University of Helsinki, 2000. http://ethesis.helsinki.fi/julkaisut/mat/fysii/vk/vainonen-ahlgren/.
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Vaiglova, Petra. "Neolithic agricultural management in the Eastern Mediterranean : new insight from a multi-isotope approach." Thesis, University of Oxford, 2016. https://ora.ox.ac.uk/objects/uuid:c8824136-da35-43b2-a700-f458d0cc2fdf.
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The work presented in this dissertation explores the nature of agro-pastoral strategies developed by Neolithic farmers as a way to understand how early food production was inter-twined with environmental and socio-economic opportunities and constraints. Towards this end, a multi-isotope approach is used to address questions of scale and intensity of crop cultivation and animal management at the archaeological sites of Kouphovouno, southern Greece, Makriyalos, northern Greece, and Çatalhöyük, south-central Turkey. Measurements of stable carbon, nitrogen, oxygen and strontium isotope values of carbonized plant remains, human and animal bone collagen and animal tooth enamel are used to examine the similarities and differences in the types of treatments that individual species of plants and animals received during the agricultural cycle at the distinct locations. The results show that farmers at the three sites developed variable methods for exploiting the arable and pastoral landscape and catering to their economic and culinary needs. The discussion considers the implications of these findings to our understanding of the complexity and adaptability of early farming systems.
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Coularis, Cindy. "Dynamique et transfert du carbone dans le bassin versant de la Loire : Traçage par les isotopes du carbone." Thesis, Université Paris-Saclay (ComUE), 2016. http://www.theses.fr/2016SACLS132.
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Cette thèse présente une étude du cycle du carbone dans la Loire et ses principaux affluents dans le but (1) de décrire, en s’appuyant sur la composition isotopique (14C et 13C), les sources, la nature et l’âge du Carbone Inorganique et Organique Dissous (CID, COD) et du Carbone Organique Particulaire (COP) prélevés lors de quatre missions en 2013-2014 et (2) d’utiliser le carbone 14 anthropique, présent dans les rejets liquides des 5 Centres Nucléaires de Production d’Electricité (CNPE) en service sur le bassin, comme traceur de transfert de carbone entre les différentes phases.Les archéologues ont mis en évidence que les âges radiocarbone déterminés sur des échantillons d’os ou de matériels non-humains (poteries, céramiques, sédiments…) ne sont pas à l’équilibre avec l’atmosphère de l’époque et nécessitent une correction. Ce biais provient de l’âge de l’eau ingérée ou utilisée et plus précisément de l’âge du CID appelé âge réservoir. Dans la Loire et ses affluents, le CID est principalement issu de l’érosion et de la dissolution du substrat géologique. Les concentrations en CID sont plus élevées en terrain sédimentaire carbonaté localisé en Loire moyenne. Les âges réservoirs étant directement corrélés à la teneur en CID, ils présentent une grande variabilité spatiale (de 135 à 2251 années 14C) du fait de la traversée de zones géologiques plus ou moins carbonatées par la Loire et ses affluents.Par ailleurs, ce CID est principalement consommé lors des processus photosynthétiques pour produire le COP algal. Ce COP algal est l’une des deux composantes de la matière organique (MO) particulaire avec le COP détritique. Les concentrations en COP suivent un cycle temporel très marqué avec des teneurs plus élevées au printemps. Le marquage du carbone algal dépend de la signature isotopique du CID utilisé lors de la synthèse chlorophyllienne. Les âges réservoirs déterminés dans le COP varient alors entre 124 et 1597 années 14C avec une variation spatio-temporelle identique à celle observée dans le CID. La proportion de carbone algal, variant entre 2 et 100%, dépend de la rivière et des conditions climatiques et hydrologiques sans qu’il soit possible d’énoncer une règle générale. La composante détritique du COP possède un marquage proche du COP et du COP algal impliquant que ce carbone détritique n’est pas d’origine géologique et donc qu’il n’est pas réfractaire.La décomposition de cette MO particulaire est une source de COD au même titre que l’activité métabolique des organismes (lyse et exsudation) et l’apport de vieille MO par la rivière, le lessivage des sols ou les nappes souterraines. Les concentrations en COD suivent donc les mêmes cycles saisonniers que le COP. Cependant, les teneurs sont plus élevées que celles du COP et augmentent peu le long des rivières (±1mg/L). Il peut être âgé si le COP et/ou la MO exportée sont anciens. Ainsi, les âges réservoirs dans le COD sont compris entre 101 et 2494 années 14C en avril 2013 avec des âges plus vieux en zone agricole.L’utilisation du radiocarbone anthropique a permis, outre la visualisation des transferts entre les différentes phases, de confirmer l’émission de 14C enrichi (ou actif) sous la forme CID par les CNPE et infirmer celle d’une composante 14C anthropique actif dans le COP et le COD. Cependant, l’activité 14C du CID ne représente pas l’activité totale du rejet en raison des échanges eau-atmosphère induisant un flux sortant de 14C. Le COP marqué enregistre l’activité initiale du rejet liquide en utilisant le CID émis par les CNPE. Le COP étant isolé de l’atmosphère, l’activité mesurée dans le COP est proche de son activité d’origine dans le rejet.L’acquisition de toutes ces données et la compréhension des processus de transferts entre CID, COP et COD permettra d’améliorer le modèle de prédiction existant et à terme, d’anticiper le comportement de ce radionucléide dans le milieu récepteur de son émission à son arrivée dans l’estuaire puis dans l’Océan AtlantiqueThis thesis focuses on carbon cycle in the Loire River and its major tributaries. It aims to (1) use isotopic composition (14C and 13C) to describe the sources, the nature and the age of the Dissolved Inorganic and Organic Carbon (DIC, DOC) and of the Particular Organic Carbon (POC) sampled during four campaigns in 2013 and 2014; and (2) to use anthropogenic 14C found in the liquid releases of the 5 Nuclear Power Plants (NPP) operating in the basin as a tool to track carbon transfer between the different phases.Archaeologists demonstrated that 14C ages of samples coming from bones or non-human material (potteries, ceramics, sediments,…) are not in balanced with the atmosphere of the time they were created and thus need to be corrected. This bias stems from the age of water (as beverage or raw material), and more precisely the DIC age, also known as reservoir age. In the Loire River and its tributaries, DIC mainly comes from erosion and dissolution of the geological substratum. DIC concentrations are higher in the carbonated areas located in the middle Loire. As the reservoir ages are directly related to the DIC content, their values present a wide spatial variability (from 135 to 2251 yr 14C BP) because the Loire River and its tributaries cross areas with variable content of carbonates among their geological formations.Also, DIC is mainly absorbed during photosynthetic processes that produce algal POC. Algal POC and detrital POC form the particulate organic matter (OM). POC concentrations follow a temporal cycle with higher values during Spring time. Algal carbon marking depends on the DIC isotopic signature used by the chlorophyll synthesis. Reservoir ages calculated from POC values range from 306 to 1597 14C years, with the same spatial and temporal variation as the DIC. Algal carbon ratio, ranging from 2 to 100%, depends on the river, and climatic and hydrologic conditions. However, no systematic pattern can be found. The detrital fraction of POC has an activity close to the activity of POC and algal POC involving that the component is not of geological origin and thus, it is not refractory.The decomposition of this particular OM, the metabolic activity of organisms (lysis and exudation) and the input of old OM from the river, the soil or the groundwater are all sources for DOC production. Thus, DOC concentrations follow the same seasonal pattern as the POC. However, DOC contents are higher than the POC ones, and increase a bit from upstream to downstream (±1mg/L). It can be aged if POC and/or exported OM are old. Thus reservoir ages in the DOC range from 101 to 2494 14C years in April 2013, with older ages in agricultural areas.Not only did the use of anthropogenic 14C made it possible to visualize transfers between different phases, but also it confirmed the emission of enriched 14CDIC and unconfirmed the emission of 14CPOC and 14CDOC by the NPP. However, the 14CDIC activity does not represent the complete activity of the release because of water-atmosphere exchange involving 14C outflow. The marked POC records the initial NPP liquid release activity using the DIC from the NPP. The POC being isolated from the atmosphere, the POC measured activity is close to the originate activity in the release.All these data combined to the understanding of the transfers processes between DIC, POC and DOC will make it possible to improve the existing prediction model and, eventually, to anticipate the behavior of this radionuclide in the river from its emission to its arrival in the estuary and then in the Atlantic Ocean
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Hall, Nicola. "Stable isotopes, molecular markers and water use in Brassicas." Thesis, University of Newcastle Upon Tyne, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.324874.
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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'atmosphèreThe 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
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Sernagiotto, Erica Regina [UNESP]. "Rastreabilidade da farinha de vísceras de aves em codornas submetidas a longo período de criação utilizando a técnica dos isótopos estáveis 'delta' 'intpot. 13 c' e 'delta' 'intpot. 15 N'." Universidade Estadual Paulista (UNESP), 2009. http://hdl.handle.net/11449/95279.
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Universidade Estadual Paulista (UNESP)
O presente trabalho teve por objetivo avaliar a capacidade da técnica dos isótopos estáveis em rastrear a farinha de vísceras de aves (FVA), na alimentação de codornas de corte criadas por longo período, após a substituição da dieta com 8% de FVA por dieta vegetal. Foram utilizadas 320 codornas, distribuídas aleatoriamente em oito tratamentos: dieta vegetal (T1) e sete tratamentos com inclusão de 8% de FVA na dieta, um mantendo a dieta até o final do período experimental (T2), e nos demais a dieta foi substituída aos 42; 56; 70; 84; 98; 112 dias; respectivamente, por dieta vegetal. Para coleta das amostras de músculo peitoral foram sacrificadas ao acaso, quatro aves (n = 4) por tratamento, a cada 14 dias, sendo que no T1 e T2 tiveram início aos 42 dias e nos demais a partir da troca das dietas. Os resultados isotópicos obtidos foram submetidos à análise multivariada de variância (MANOVA) com auxílio do procedimento GLM do programa estatístico SAS. Os tratamentos diferiram do vegetal quando as aves foram sacrificadas duas semanas após a troca da dieta; após esse período os tratamentos experimentais tiveram comportamento semelhante ao vegetal, exceto o T3, que se mostrou semelhante ao T1 no abate 14 dias após a troca da dieta; e do T2 que em todos os períodos de comparação diferiu do T1. Conclui-se que a aplicação da técnica dos isótopos estáveis de carbono e nitrogênio na rastreabilidade da FVA, na alimentação de codornas de corte criadas por longo período é possível nas aves abatidas 14 dias após a troca de dieta, com exceção das aves sacrificadas aos 56 dias de idade.
The present work aimed to evaluate the capability of the stable isotope technique to trace poultry visceral meal (PVM) in the diet of meat quails raised for a long period after substitution of an 8% PVM diet for a vegetable diet. Three hundred and twenty poultries (320) were randomly distributed into eight treatments: vegetable diet (T1) and seven treatments containing 8% PVM in the diet: in one treatment, the same diet was kept until the end of the experimental period (T2), and in the remaining treatments, the diet was substituted at 42, 56, 70, 84, 98, and 112 days, respectively, for a vegetable diet. To collect chest muscle samples, four poultries (n = 4) per treatment were randomly sacrificed at every 14 days, starting at 42 days in T1 and T2 and from diet substitution in the remaining treatments. The obtained isotopic results were subjected to multivariate analysis of variance (MANOVA) using the GLM procedure of SAS statistical software. Treatments differed from the vegetable diet when poultries were sacrificed at two weeks following the diet substitution; after such period, the behavior of experimental treatments was similar to that of the vegetable diet, except for T3, which was similar to T1 at slaughtering at 14 days after the diet substitution, and T2 which, in all comparison periods, differed from T1. In conclusion, the technique of stable isotopes of carbon and nitrogen can be used to trace PVM in the diet of meat quails slaughtered at 14 days after diet substitution, except for poultries sacrificed at 56 days.
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Lo, Tierzo Vivian 1982. "Turnover do carbono nos tecidos de suínos em diferentes fases de crescimento /." Botucatu : [s.n.], 2012. http://hdl.handle.net/11449/104053.
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Orientador: Carlos DucattiBanca: Fabiana Ribeiro Caldara
Banca: Dirlei Antonio Berto
Banca: Juliana Célia Denadai
Banca: Léa Silvia Sant'Ana
Banca: José Albertino Bendassolli
Resumo: Este trabalho objetivou determinar o turnover do carbono no sangue, pâncreas e tíbia de suínos em diferentes períodos de crescimento, utilizando a técnica de isótopos estáveis. Foram utilizados 132 machos castrados e fêmeos, distribuídos ao acaso em quatros tratamentos que consistiam da substituição da dieta a base de milho (planta de ciclo fotossintético C4) por dieta a base de arroz (plantas do ciclo fotossintético C3) em dias distintos: 21; 42; 63; 110 dias de idade, respectivamente para os tratamentos 1, 2, 3 e 4. Para mensurar o turnover do carbono (diluição isotópica) nos tecidos em determinado intervalo de tempo, foram utilizados o modelo de equações de função exponencial do tempo ou modelo sigmoidal de regressão de Boltzmann. Os valores de meias-vidas foram: 15,9; 19,0 e 16,8 dias para o sangue; 14,1; 9,68 e 10,4 dias para o pâncreas; 14,3; 8,0 e 15,1 dias para tíbia com medula nos tratamentos com substituição aos 21, 42 e 63 de idade respectivamente. O pâncreas de acordo com valores de meia vida apresentou um rápido turnover, o sangue e a tíbia com medula apresentaram maiores valores de meia vida
Abstract: This study aimed to determine the turnover of carbon in the blood, tibia and pancreas of pigs at different growth periods, using the technique of stable isotopes. We used 132 barrows and females were randomly assigned into four groups consisting of replacing the corn-based diet (plant C4 photosynthetic cycle) by diet of rice (C3 photosynthetic cycle plants) on different days: 21; 42, 63; 110 days of age, respectively for treatments 1, 2, 3 and 4. To measure the turnover of carbon (isotope dilution) in tissues given time interval, we used the model equations exponential function of time or template Boltzmann sigmoidal regression. Values of half-lives were 15.9, 19.0 and 16.8 days for the blood; 14.1, 9.68 and 10.4 days for the pancreas, 14.3, 8.0 and 15, one day to the tibia with bone replacement treatments at 21, 42 and 63 of age respectively. The pancreas according to half-life values showed a rapid turnover, blood and tibia with bone showed higher half-life
Doutor
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Leask, Peter John. "Probing nuclear molecular analogue states in carbon, boron and beryllium isotopes." Thesis, University of Birmingham, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.369340.
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Bradbury, Harold John. "Calcium isotope insight into the global carbon cycle." Thesis, University of Cambridge, 2018. https://www.repository.cam.ac.uk/handle/1810/273425.
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Over the course of my PhD, I developed the analytical capability to measure calcium isotopes at the University of Cambridge and analyzed calcium isotopes in a range of fluids and minerals in modern and past environments. After discussing my methodological development, I report my work in the glacial precursor to the Dead Sea. Here, the calcium isotope composition of aragonite varies synchronously with lake level fluctuations over the last 70,000 years. My numerically reconstructed lake calcium budget led me to conclude that 20,000 years ago, the Dead Sea was wetter than modern conditions, rather than colder and drier, as had previously been proposed. The primary focus of my PhD research was understanding the sedimentary sink for carbon. The formation of authigenic carbonate in marine sediments is caused by the microbial degradation of organic matter. I used pore fluid measurements and a numerical model to identify zones of authigenic carbonate precipitation. This knowledge was then combined with an understanding of the microbial processes that occur beneath the seafloor to determine the link between microbial activity and authigenic carbonate formation. Two processes, sulfate reduction and the anaerobic oxidation of methane were determined to be the main drivers of authigenic carbonate precipitation. In order to assess the importance of the carbon isotope signal imparted by each of the two identified processes, I created Artificial Neural Networks to predict the areal extent of authigenic carbonate precipitation and the dominant microbial process driving the precipitation. My ANNs identified that 37% of the modern seafloor is precipitating authigenic carbonate, which leads to a flux of 1.2*10^12 moles of carbon per year, of which 88% is due to the anaerobic oxidation of methane, and 12% is due to sulfate reduction. This represents 2-3% of the modern global carbon deposition, however I was able to show that this would be significantly higher in the geological past when ocean conditions were vastly different to how they are today. Finally, I conclude by proposing that some variations in the global carbon cycle in the past can be explored by linking marine calcium concentrations to authigenic carbonate formation and the flux of alkalinity from the seafloor.
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Lee, Kern Y. "Carbon Cycling in Tropical Rivers: A Carbon Isotope Reconnaissance Study of the Langat and Kelantan Basins." Thèse, Université d'Ottawa / University of Ottawa, 2014. http://hdl.handle.net/10393/30429.
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Despite the importance of tropical rivers to the global carbon cycle, the nature of carbon cycling within these watersheds has been dealt with by only a handful of studies. The current work attempts to address this lack of information, using stable isotope and concentration measurements to constrain sources and sinks of carbon in two Peninsular Malaysian watersheds. The basins are located on the central-western and northeastern coasts of the Malaysian Peninsula, and are drained by the Langat and Kelantan Rivers, respectively. Water samples were collected from three points along the two rivers twice a month, in addition to the sampling of groundwater in adjacent aquifers.
Principal component analyses (PCA) on water chemistry parameters in the Langat and Kelantan Rivers show the dominance of geogenic and anthropogenic influences, grouped in 4 to 6 components that comprise over 50 % of the total dataset variances. The geogenic input is reflected by components showing strong loadings by Ca, Mg, Mn, Si, and Sr, while anthropogenic influences via pollution are indicated via strong loadings by NO3, SO4, K, Zn and Cl. The carbon isotope and concentration data appear unrelated to these groups, suggesting that the riverine carbon cycle in both locations is dominated by other factors. These may include alternative sources of organic pollution, or inputs from the local vegetation and soils.
The mean riverine 13CDOC of -27.8 ± 2.9 ‰ and -26.6 ± 2.2 ‰ in the Langat and Kelantan Basins, respectively, are consistent with the dominance of C3-type vegetation in both watersheds. Riverine 13CDIC signatures approach C3-like values at high DIC concentrations, with measurements as low as -19 ‰ in the Kelantan Basin and -20 ‰ observed in the Langat Basin, consistent with a biological origin for riverine DIC. However, the average 13CDIC in river water is 13C-enriched by about 10 ‰ relative to the expected C3 source in both rivers, and this 13C- enrichment appears to be largest with smaller DIC concentrations.
Because of the overpressures of CO2 in the rivers, entrainment of isotopically-heavy atmospheric CO2 is not a likely explanation for the observed 13C-enrichment. Theoretically, dissolution of carbonates could be an alternative source of 13C-enriched carbon, but this lithology is scarce, particularly in the Langat watershed. The increase in DIC downstream and generally high pCO2 values in most river sections argues against aquatic photosynthesis as a primary causative factor for the observed isotopic enrichment. This elimination process leaves the speciation of riverine DIC and the evasion of CO2 as the most likely mechanisms for 13C-enrichment in DIC, via isotope fractionation during HCO3- hydration and CO2 diffusion. Potentially, methanogenic activity could also be, at least partially, responsible for the 13C-enrichment in DIC, particularly immediately downstream of the Langat Reservoir, but due to the absence of empirical data, this must remain only a theoretical proposition.
The aquatic chemistry and dissolved carbon data suggests that pollution discharge into the Langat and Kelantan Rivers is the major factor that is responsible for the considerable CO2 overpressures and high DIC and DOC concentrations in the river waters, particularly in the downstream sections. This pollution is likely of biological origin, via sewage and palm oil mill effluent (POME) discharge, and therefore isotopically indistinguishable from natural C3 plant sources.
Carbon budgets of the Langat and Kelantan River show CO2 degassing to be a significant mechanism of fluvial carbon loss, comprising roughly 50 %, or more, of the total riverine carbon export in both watersheds. The remainder of the river carbon is transported to the ocean in the form of DIC, DOC and POC in broadly comparable proportions. However, the combined riverine carbon export from the Kelantan and Langat Basins amount to 2 % or less of the total carbon sequestration of the watersheds. Thus, most of the sequestered carbon is returned to the atmosphere via respiration, with smaller amounts incorporated into ecosystem biomass .
These results highlight the complexity of carbon cycling in tropical rivers, and agree with previous studies in showing riverine systems to be more than simple conduits of carbon from the land to the ocean.
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Harrison, Roman Gastrell. "Paleodiet studies using stable carbon isotopes from bone apatite and collagen." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape2/PQDD_0021/NQ54785.pdf.
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Wellman, Toby. "Carbon and oxygen stable isotopes from recent and fossil Australian crustaceans /." Title page, contents and abstract only, 2001. http://web4.library.adelaide.edu.au/theses/09SB/09sbw4528.pdf.
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Webb, Sarah Christine. "Stable carbon and nitrogen isotopes in insects : the influence of diet." Thesis, University of Oxford, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.389063.
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Asher, Cameron Michael. "Carbon and nitrogen isotopes in lichen as a geothermal exploration tool." Thesis, University of Canterbury. Geological Sciences, 2014. http://hdl.handle.net/10092/9651.
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Lichen have been used as indicators of atmospheric pollutants since Grindon (1859) observed lichen populations declining in a polluted Southern Lancashire in the mid-1800s. Since then lichen have been used in a number of atmospheric studies. A study by Tozer et al. (2005) attempted to use nitrogen isotopes of lichen and free-living algae as indicators of geothermal ‘pollution’ near Rotorua and the Te Kopia Geothermal Area, but was unable to show a correlation with distance to geothermal features. This thesis aims to build from Tozer et al. (2005) and use both carbon and nitrogen isotopes in lichen as an exploration tool in geothermal areas.
Three transects were completed: one across the South Island from Christchurch to Greymouth (non-geothermally influenced area), and two along (north-south) and across (east-west) the Taupo Volcanic Zone (TVZ) in the North Island (geothermally influenced area). In addition to these three transects, sampling at higher spatial resolution was conducted in the immediate vicinity of the Orakonui Stream geothermal springs at the Ngatamariki Geothermal Area. The three transects showed large variation, largely due to the type of land use from which the sample was collected. The highest nitrogen contents (1.62 ± 0.39%) and less negative nitrogen isotopic compositions (-9.44 ± 0.39‰) were found over farmland, while both exotic and native forests had low nitrogen (1.08 ± 0.35% and 1.03 ± 0.44‰, respectively) and highly negative isotopic compositions (-12.94 ± 0.26‰ and -12.09 ± 0.45‰, respectively). The statistical difference between land use classes is hypothetically explained by variations in nitrogen sources, with intensive farmland volatilizing NH3 with δ15N values of -6 to -10‰ (Tozer et al., 2005), while forest areas are expected to produce biogenic nitrogen from decomposition with more negative δ15N.
At Ngatamariki, δ13C and δ15N isoscapes were produced, with both showing a large isotopic anomaly (>-23.5 and >-8‰, respectively) to the north and north-west of the study area, correlating with areas of farmland, although in some places the δ15N values exceed 0‰, which is unexplained. A study by Hanson (2014) identified diffuse soil flux using δ13C in the vicinity of the Orakonui South Main Crater to have a geothermal signature, the same location in which a small relatively less-negative δ13C anomaly (>-23.5‰) is seen in lichen isotopes. While this could be attributed to a geothermal influence, it could also be due to the effect of substrate the lichen lives on and a reduction in carbon sourced from biogenic respiration.
Ultimately, there is the potential for isotopes in lichen to be used as a geothermal exploration tool, although this method needs to be investigated in a higher flux geothermal area, such as Rotokawa, 7km to the south of Ngatamariki.
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Boyd, Stuart Richard. "A study of carbon and nitrogen isotopes from the Earth's mantle." Thesis, Open University, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.252682.
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Simpson, Nicola Jane. "Carbon isotopes and the plant fossil record : taphonomic and diagenetic controls." Thesis, Open University, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.301876.
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Trandel, Marlee Anne. "Nitrogen and Carbon Stable Isotopes in Organically and Conventionally Grown Tomatoes." OpenSIUC, 2016. https://opensiuc.lib.siu.edu/theses/2013.
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Tomatoes (Lycopersicon esculentum L.) require high amounts of nitrogen to maximize fruit production. The type of nitrogen and timing of fertilizer applications are important in tomato production systems to reduce nitrogen losses while optimizing yields. A two-year greenhouse study was conducted to determine the effects of organic and inorganic fertilization treatments on nitrogen and carbon isotopic compositions of tomato plant leaves and fruit at immature and mature stages of plant growth. The carbon and nitrogen isotopic ratios together will also help to better depict trends that develop from conventional versus organically grown tomatoes and their resulting water use efficiency (WUE). ‘Better Bush’ tomatoes were grown in 8 L plastic pots filled with 1:1:1 steamed-sterilized sand:silt loam soil:peat mix. Eight fertility treatments were evaluated: no fertility, synthetic Miracle Grow® (MG), organic bonemeal and bloodmeal (BB), BB with liquid Earthjuice (BBL), BB with 25% vermicompost (VC), BBL with 25% VC, MG with 25% VC, and no fertility with 25% VC. The results indicated that for both growth stages, δ15NAir differed (P ≤ 0.05) between fertility treatments, while no major differences were observed for δ13CVPDB (P > 0.05), although conventionally fertilized tomatoes with MG and MG with 25% VC tended to have lower δ13CVPDB values suggesting a greater transpirational water loss through open stomata. The organic treatments with VC had higher δ15NAir values than the conventional or no added fertility treatments for all five leaflets from three different branches, fruit skins from the first two fruit clusters, fruit juices from the first two clusters and soil samples. Generally, the 15N/14N stable isotope values of tomato foliage and fruit are distinctly different between organic and conventional fertilizers, which could provide a powerful forensic tool in fingerprinting tomatoes grown by organic farming methods. Therefore, nitrogen isotopes can distinguish among different fertility treatments and also help to label the VC applications, which are thought to provide better fertility management due to less soil leaching and volatilization.
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Johnson, Brian James. "The carbon-13 content of atmospheric formaldehyde." Diss., The University of Arizona, 1988. http://hdl.handle.net/10150/184320.
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A measurement of the stable carbon isotopic composition of atmospheric formaldehyde was undertaken as a means of testing current photochemical theories. Sulfito surfaces were shown to meet the stringent analytical requirements of the project; an extensive characterization of these surfaces was performed for the first time. Models were developed to describe the chemical evolution of the surfaces during sampling. It was established that potassium salts have more favorable properties for an atmospheric collection system than do sodium salts. Considerable selectivity in collection was also demonstrated. A highly selective multistep procedure for the isolation and chemical oxidation of collected formaldehyde was developed expressly for this project. A previously unreported combination of reagents, HgCl₂ and AgClO₄, was used in the final reaction step of the procedure. Through the use of synthetic samples, the method was shown to be isotopically reproducible and highly chemically selective. The first data for the carbon-13 content of atmospheric formaldehyde have been obtained, with an observed mean value of δ¹³C = -17‰. This value is enriched in carbon-13 over the known atmospheric sources of formaldehyde; isotopic fractionation in the atmosphere is therefore indicated. It is believed that fractionation due to photolysis can account for the observed effect.
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Assis, Cecília Kruszynski de. "Diet and ecosystem services of insectivorous bats assessed with stable isotopes." Universidade de São Paulo, 2016. http://www.teses.usp.br/teses/disponiveis/64/64135/tde-07032019-103440/.
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Ecosystem services are natural environmental functions and ecological process that humans benefit from. In the present study, it was highlighted one of the services provided by bats: agricultural pest control. In Brazil, studies with insectivorous bats as potential pest suppressors are still scarce, despite the country being one of the biggest agricultural producers in the world and concentrating a high diversity of those animals. The use of heterogeneous landscapes, formed by native vegetation and crop fields, optimize the investment applied in this search. For that, it was described, for the first time, the bat assemblage in heterogeneous landscape in Piracicaba, at the campus \"Luiz de Queiroz\" that comprehends urbanized and agricultural areas, which provides many food resources for bats. Further, it was tested if there is difference in isotopic values (?13C and ?15N) between bat species related to diet, spatial foraging behavior, sex or taxonomic classification and which specie is a better pest suppressor. Bats were captured by mist nets and stable isotope analysis of carbon and nitrogen (?13C e ?15N, respectively) were used to access its food source. Through the analysis of ?13C and ?15N of insects, we determined the proportion of plants with photosynthetic cycles of C3 and C4 in bats\' diet and its trophic level. It was captured 90 bats of 11 species, three families and four dietary categories, corresponding to 66% of the total local richness estimated. From those, five are insectivorous species. Molossus molossus were the most abundant specie, followed by Artibeus lituratus and Glossophaga soricina. Carbon values showed that insectivores, frugivores and nectarivores consume insects, including pests, in different proportions per specie and diet group. Besides, ?15N values showed that bat trophic level were very similar, so bats are more generalist than usually assumed. This study points a need to quantify this important ecosystem service provided by bats that can reduce diseases and crop damagesServiços ecossistêmicos são funções dos ambientes naturais e dos processos ecológicos dos quais humanos se beneficiam. Esses benefícios podem ser acessados por uma perspectiva econômica e ecológica. No presente estudo, nós destacamos um dos serviços ambientais fornecidos por morcegos: controle de pragas agrícolas. No Brasil, os estudos com morcegos insetívoros como potenciais supressores de pragas ainda são escassos, apesar de o país ser um dos maiores produtores agrícolas do mundo e abrigar uma alta diversidade desses animais. O uso de paisagens heterogêneas, formadas por vegetação nativa e lavouras agrícolas, otimiza o investimento aplicado nessa busca. Para tanto, descrevemos, pela primeira vez, a assembleia de morcegos em um ambiente heterogêneo de Piracicaba, o campus \"Luiz de Queiroz\", que possui desde áreas urbanizadas a agrícolas, disponibilizando diversos recursos alimentares para os morcegos. Ademais, testamos se há diferenças nos valores isotópicos (?13C e ?15N) entre as espécies de morcegos em relação à dieta, comportamento espacial de forrageamento, sexo ou classificação taxonômica para identificar quais grupos são os melhores supressores de pragas agrícolas. Utilizamos redes de neblina para a captura dos morcegos e análises de isótopos estáveis de carbono e nitrogênio (?13C e ?15N, respectivamente) para acessar sua fonte de dieta. Por meio das análises, determinamos a proporção de plantas com ciclos fotossintéticos do tipo C3 e C4 na dieta dos morcegos, bem como seu nível trófico. Capturamos 90 morcegos de 11 espécies, três famílias e quatro classes de dieta, correspondendo a 66% da riqueza estimada para o local. Destas, cinco são espécies classificadas insetívoras. Molossus molossus foi a espécie mais abundante, seguida por Artibeus lituratus e Glossophaga soricina. Valores de ?13C mostraram que insetívoros, frugívoros e nectarívoros consomem insetos, inclusive pragas, em diferentes proporções por espécie e grupo de dieta. O grupo mais efetivo no controle de pragas agrícolas foi M. molossus, seguido por A. planirostris. Os valores de ?15N mostraram que o nível trófico dos diferentes grupos alimentares de morcegos foi similar, de modo que eles são mais generalistas que previsto na literatura. Nosso estudo aponta a necessidade de quantificação desse importante serviço ecossistêmico promovido por morcegos, que podem reduzir doenças e prejuízos nas lavouras, além de combater vetores de doenças
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Shelkov, Denis Alexander. "N and C isotropic composition of different varieties of terrestrial diamonds and carbonado." Thesis, Open University, 1997. http://oro.open.ac.uk/54608/.
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During the course of this research an instrument utilising combustion as a means of gas extraction capable of N, e, Ar and He analysis has been developed and the entire analytical procedure has been automated. N and e isotopic analysis has been performed on eclogitic and peridotitic diamonds (mainly from Yakutian kimberlites and the Roberts Victor kimberlite pipe). Diamonds with unusual (light and heavy relative to the peak of ol3e distribution of mantle diamonds) carbon isotopic signatures were considered for the research so that diamonds in the range of δ¹³C from -30‰ to + 2.8‰ were characterised for δ¹⁵N. The results together with data obtained previously by the others define fields for eclogitic and peridotitic diamonds on a plot of δ¹⁵N vs. δ¹³C. The model of mantle nitrogen and carbon evolution is discussed. A comprehensive comparison between carbonado and other known forms of microcrystalline diamond (framesites and shock diamonds) has been made for a number of parameters: N and e isotopic composition and N content; 4He content; morphology of the inner structure of diamond aggregates. It can be concluded that carbonado is generally similar to frame sites and all facts known about carbonado can be explained on the grounds of common mantle origin involving subducted carbon and nitrogen. Since extremely high 4He concentrations are encountered in carbonado this parameter is considered to be the most singular feature of this diamond variety and the radial distribution of 4He in single diamond crystals has been studied. A 4He content comparable with that in carbonado was found in the 30 J.lm skin of diamond crystals (up to 1.4 x 10⁻²) suggesting that carbonado could acquire high 4He concentration in the same geological processes as single diamond crystals and making carbonado indistinguishable from mantle diamonds in terms of He content. An additional result of the investigation is that the maximum of 4He diffusion coefficient for diamond at mantle P,T conditions can be estimated (≈4x10⁻²¹ ) from the 4He zoning identified in the interior of a diamond crystal from the Finsch kimberlite. A number of diamonds of impact origin from Popigai crater and Ebeliakh river placer deposits were studied for N, C and Ar isotopic compositions. It was concluded that diamonds from these two localities have resulted from separate impact events and that diamond aggregates studied are most probably consist of a mixture of different Ar and N carriers (e.g. two types of diamond grains).
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Strange, Malinda Range. "The effect of pathology on the stable isotopes of carbon & nitrogen." Diss., Online access via UMI:, 2006.
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Warrington, Anita Glasgow. "Stable isotopes of carbon and oxygen in the shells of terrestrial molluscs." Thesis, University of Liverpool, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.316976.
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Harwood, Kirsty. "Variation in the stable isotopes of oxygen and carbon within forest canopies." Thesis, University of Newcastle Upon Tyne, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.360330.
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Cutajar, Josephine-Anne. "Characterisation of aerosols using carbon and lead stable isotopes and trace elements." Thesis, Open University, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.339859.
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Cassar, Nicolas. "Carbon-concentrating mechanisms and [beta]-carboxylation their potential contribution to marine photosynthetic carbon isotope fractionation /." Thesis, University of Hawaii at Manoa, 2003. http://proquest.umi.com/pqdweb?index=0&did=765084611&SrchMode=2&sid=6&Fmt=2&VInst=PROD&VType=PQD&RQT=309&VName=PQD&TS=1233178277&clientId=23440.
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Gentry, David Keith. "Seasonal isotope and trace-metal profiles of serially-sampled Conus gastropods: proxies for paleoenvironmental change." Thesis, Texas A&M University, 2003. http://hdl.handle.net/1969.1/3871.
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We test the fidelity of shallow-water gastropod skeletons as multi-proxy archives of seasonal paleo-environmental change by performing isotopic and trace-metal analyses on specimens of Conus ermineus from the Gulf of Mexico. Four adult specimens were collected from Stetson Bank in the Flower Garden Banks National Marine Sanctuary during the summer of 2002. Shell samples were milled along axes of growth to produce time-series profiles spanning up to eight years. We corrected the profiles for growth rate effects and compared the tuned results with in situ temperature and salinity records at the reef surface and temperature profiles from nearby surface buoys. Examination of sample densities in δ18O cycles shows that shell growth is faster during summers and slower during winters. Tuning the profiles versus time yields δ18O values that co-vary closely with seasonal temperatures to a high degree of coherency (R2 = 0.84). The δ13C profiles show cyclic variation modified by ontogenetic decreases in δ13C. These ontogenetic trends are attributable to decreasing metabolic efficiency, while seasonal cycles reflect hydrographic changes in the gastropods habitat. Salinity and δ13C of dissolved inorganic carbon show a strong correlation at Stetson Bank (R2 = 0.80), and early summer shell δ13C minima coincide with local salinity minima during times of peak river discharge. The terminations of these δ13C minima occur during annual upcoast reversals of shelf currents in this area. These effects are augmented by summer stratification and productivity minima that further decrease seawater δ13C. Sr/Ca ratios increase through ontogeny, most likely due to decreasing metabolic efficiency. However, seasonal variations in Sr/Ca profiles show strong similarity with δ18O profiles, confirming the temperature dependence of Sr/Ca and minimal influence of salinity on shell δ18O at Stetson Bank. The results of this study show that tuned δ18O and Sr/Ca profiles can be used to reconstruct seasonal paleotemperatures. Carbon isotope profiles and environmental data also demonstrate the utility of Conus δ13C as a proxy for freshwater flux and shelf circulation.
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Ogle, Neil. "The measurement and modelling of #delta#'1'3C in Irish oaks." Thesis, Queen's University Belfast, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.295402.
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Ahad, Jason Michael Elias. "Monitoring stable carbon isotopes during biodegradation of toluene, implications for contaminated site assessment." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape2/PQDD_0023/MQ50399.pdf.
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Hemming, D. L. "Stable isotopes in tree rings : biosensors of climate and atmospheric carbon-dioxide variations." Thesis, University of Cambridge, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.603940.
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The objective of this dissertation is to use the annual tree ring width and cellulose carbon and hydrogen stable compositions off three native British tree species: common beech (Fagus silvaatica L.), pedunculate oak (Quercus robur L.) and scots pine (Pinus sylvestris L.), for the period 1895 to 1994, to examine the responses of these trees to recent changes in climate and atmospheric CO2. The high frequency δ13C series of all three species display the most significant correlations with the climate parameters and, using simple regression models, it is also evident that this tree ring measure provides the most accurate climate reconstructions. Vapour pressure deficit, averaged for the months July to September, is the climate parameter most significantly correlated with the δ13C data. However, it is shown that this may not necssarity mean that the trees are responding dominantly to this parameter. Although it is apparent that the pine species δ13C series is the most responsive of the species to climate fluctuations, it is also noted that the combined δ13C signal from all three tree species displays an enhanced climate signal. Superimposed on the common climate signals are long term trends that are comparable for the δ13C series of all three species and the δD of the pine trees, but do not show any common signal for the other δD series or any of the ring width series. Converting the δ13C data to indicators of leaf gas exchange, it is evident that the rapid increasing trend in atmospheric CO2 concentration ([CO2]), that began around 1930, coincides with a rising trend in leaf intrinsic water use efficiency but does not coincide with a change in the internal concentration of CO2 in the leaf (ci). The results suggest that the increasing [CO2] induced all three tree species to increase assimilation rate and reduce stomatal conductance to such an extent that ci remained initially constant. As there are no consistent increases in ring widths during this period, the dominant response could be inferred to be stomatal conductance. However, preferential partitioning of photosynthates to other plant organs, especially roots, is a common response of C3 plants to increased [CO2] and it is more likely that both assimilation rate and stomatal conductance have changed.
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Lee-Thorp, Julia Anne. "Stable carbon isotopes in deep time : the diets of fossil fauna and hominids." Doctoral thesis, University of Cape Town, 1989. http://hdl.handle.net/11427/21732.
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Bibliography: pages 126-148.This thesis describes the development, testing and application of a technique for extending carbon isotopic dietary tracing millions of years in time,. using the mineral phase of calcified tissues (apatite) as alternative sample material to collagen. The results reported here provide empirical evidence for the validity of the technique. Investigation of the isotopic relationships between diet, collagen and apatite, using a large sample of modem fauna with known diets, confirms that the isotopic relationship between collagen and apatite changes with trophic level.
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Le, Roux Debbie Jeanette. "Growth, water use efficiency and stable carbon isotopes in commercial clones of Eucalyptus." Master's thesis, University of Cape Town, 1993. http://hdl.handle.net/11427/18327.
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The expansion of Eucalyptus plantations to supply timber for an increasing population in South Africa will result in a great reduction in the country's run-off water. If Eucalyptus continues to be the source of timber in South Africa, the selection of more water use efficient species for planting in existing and new areas has to be implemented. An understanding of the physiological factors ruling growth and water use efficiency in Eucalyptus is needed to develop selection criteria for improved water use efficiency and harvestable stem production under a limited water supply. This study investigated the effects of soil moisture availability on the growth and water use efficiency of 6 commercial clones of Eucalyptus commonly grown in South Africa with the aim of determining the following: (i) The extent of clonal variation in growth, dry mass allocation patterns, water use efficiency and the water cost of wood production at 16 months after planting. (ii) The influence of plant physiological traits such as patterns of dry mass allocation, canopy leaf area, leaf canopy density, specific leaf area, foliar nitrogen concentration and instantaneous rates of photosynthesis and transpiration, on growth, water use efficiency and the water cost of wood production. (iii) The complications associated with sampling for stable carbon isotope ratios (δ¹³C) within a eucalypt canopy and the potential use of δ¹³C in plant tissues as a tool for ranking clonal water use efficiencies.