Literatura académica sobre el tema "Isotopes calcium"
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Artículos de revistas sobre el tema "Isotopes calcium"
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Chandra, Subhash. "Imaging transported and endogenous calcium independently at a subcellular resolution: ion microscopy imaging of calcium stable isotopes". Proceedings, annual meeting, Electron Microscopy Society of America 50, n.º 2 (agosto de 1992): 1604–5. http://dx.doi.org/10.1017/s0424820100132650.
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Ion microscopy, based on secondary ion mass spectrometry (SIMS), is a unique isotopic imaging technique. The use of stable isotopes as tracers and their SIMS localization at a subcellular resolution has introduced a significant new approach for molecular localization and ion transport studies. A molecule of interest may be tagged with stable 2H, 13C, 15N, etc. and imaged with SIMS for its intracellular location. Stable isotopes of physiologically important elements such as calcium and magnesium provide excellent tracers for ion transport imaging studies with SIMS. in a recent study with 44Ca, the brush border region in the small intestine was observed to be the main barrier for calcium transport from the intestinal lumen to the lamina propria region in chickens suffering from Rickets, a vitamin D-deficiency condition.An example of the use of 44Ca stable isotope for imaging calcium-calcium exchange between the intracellular and extracellular calcium with SIMS is shown in figure 1. 3T3 cells were grown on high purity germanium chips to about 80% confluency.
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Fujii, Y., J. Hoshi, H. Iwamoto, M. Okamoto y H. Kakihana. "Calcium Isotope Effects in Ion Exchange Electromigration and Calcium Isotope Analysis by Thermo-Ionization Mass Spectrometry". Zeitschrift für Naturforschung A 40, n.º 8 (1 de agosto de 1985): 843–48. http://dx.doi.org/10.1515/zna-1985-0807.
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Calcium ions were made to electromigrate along a cation exchange membrane. The abundance ratios of the calcium isotopes (Ca-40, 42, 43, 44, 48) in the migrated bands were measured by thermo-ionization mass spectrometry. The lighter isotopes were enriched in the front part of the migrated band. The increments in the isotope abundance ratios were found to be proportional to the mass differences of the isotopes. The observed e-values per unit mass difference (ε/ΔM) were 1.26 x 10-4 (at 20 °C), 1.85 x 10-4 (at 25 °C) and 2.4 x 10-4 (at 40 °C). The mass spectrometry was improved by using a low temperature for the evaporation of CaI2.
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Yergey, Alfred L., Steven A. Abrams, Nancy E. Vieira, Richard Eastell, Laura S. Hillman y David G. Covell. "Recent studies of human calcium metabolism using stable isotopic tracers". Canadian Journal of Physiology and Pharmacology 68, n.º 7 (1 de julio de 1990): 973–76. http://dx.doi.org/10.1139/y90-147.
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Stable isotopes of calcium are used safely as tracers for calcium in human populations ranging in age from infants to postmenopausal women. Thermal ionization mass spectrometry is used to measure calcium isotope ratios with relative accuracies of about 1% for natural abundance ratios at precisions of about 1% relative to the mean. Perturbations of natural abundance ratios are determined for the calcium in blood, urine, and feces with a limit of detection of about 2 Δ% excess. The mathematical rationale for clinical studies of fractional absorption of dietary calcium and the kinetics of calcium's internal distribution are presented.Key words: calcium, tracers, stable isotopes, mass spectrometry.
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Zhao, Hongyu y Junhua Huang. "Characteristics of Calcium Isotopes at Different Water Depths and Their Palaeoenvironmental Significance for Carbonate Rocks of the Permian-Triassic Boundary in Chibi, Southern China". Minerals 12, n.º 11 (14 de noviembre de 2022): 1440. http://dx.doi.org/10.3390/min12111440.
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Calcium isotopes of carbonate rocks can trace calcium cycles and record changes in the marine environment. As published calcium isotope profiles of carbonate rocks at the Permian-Triassic boundary are rare, comparative studies on deep-water profiles were lacking for the major extinction event that occurred during this time. We present sections of different water depths in the Chibi area of southern China that we have selected for a comparative study. We analyzed carbon isotopes, calcium isotopes, as well as major and trace elements of carbonates from two sections (Chibi North and Chibi West) to obtain information on the volcanic activity, ocean acidification, as well as sea level rise and fall in the Chibi area during the mass extinction period. All carbon and calcium isotopes of carbonates from both sections are all negative after the mass extinction boundary. Carbonates from the Chibi North section have higher δ44/40Ca values and lower Sr/Ca ratios than the rocks from the Chibi West section. We propose that the negative bias of the calcium isotopes in the two sections result from diagenesis. Diagenesis transforms primary aragonite into calcite, showing the characteristics of high δ44/40Ca value and low Sr/Ca. By comparing our data with three published profiles of shallow-water carbonate rock, we recognize that calcium isotopes record gradients at different water depths. In the slope environment, the enhancement of pore fluid action near the coast caused an increase of the fluid buffer alteration, and we propose that a regression event occurred in the Chibi region during the Late Permian.
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Han, Guilin, Anton Eisenhauer, Jie Zeng y Man Liu. "Calcium Biogeochemical Cycle in a Typical Karst Forest: Evidence from Calcium Isotope Compositions". Forests 12, n.º 6 (25 de mayo de 2021): 666. http://dx.doi.org/10.3390/f12060666.
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In order to better constrain calcium cycling in natural soil and in soil used for agriculture, we present the δ44/40Ca values measured in rainwater, groundwater, plants, soil, and bedrock samples from a representative karst forest in SW China. The δ44/40Ca values are found to differ by ≈3.0‰ in the karst forest ecosystem. The Ca isotope compositions and Ca contents of groundwater, rainwater, and bedrock suggest that the Ca of groundwater primarily originates from rainwater and bedrock. The δ44/40Ca values of plants are lower than that of soils, indicating the preferential uptake of light Ca isotopes by plants. The distribution of δ44/40Ca values in the soil profiles (increasing with soil depth) suggests that the recycling of crop-litter abundant with lighter Ca isotope has potential effects on soil Ca isotope composition. The soil Mg/Ca content ratio probably reflects the preferential plant uptake of Ca over Mg and the difference in soil maturity. Light Ca isotopes are more abundant in mature soils than nutrient-depleted soils. The relative abundance in the light Ca isotope (40Ca) is in the following order: farmland > burnt grassland > forests > grassland > shrubland. Our results further indicate that biological fractionation in a soil–plant system is a vital factor for Ca–geochemical transformations in soil surface systems.
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Gordon, Gwyneth W., Jorge Monge, Melanie B. Channon, Qing Wu, Joseph L. Skulan, Ariel D. Anbar y Rafael Fonseca. "Calcium Isotopic Composition and Its Association With Multiple Myeloma Disease Activity". Blood 122, n.º 21 (15 de noviembre de 2013): 3157. http://dx.doi.org/10.1182/blood.v122.21.3157.3157.
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Abstract Multiple myeloma (MM) is characterized by clonal proliferation of a neoplastic plasma cell and its production of a monoclonal immunoglobulin; evolving from an asymptomatic pre-malignant stage named monoclonal gammopathy of undetermined significance (MGUS). At the time of diagnosis with MM, lytic lesions are present in approximately 70-80% of patients. Lytic lesions increase the risk for skeletal related events as well as treatment costs, while lowering quality of life and overall survival. Metastatic bone surveys underestimate bone disease since plain radiographs demonstrate abnormalities until at least 30% of trabecular bone has been lost and cannot provide information about ongoing bone remodeling. Bone scintigraphy lacks usefulness in following bone disease due to decreased osteoblast activity in MM, while Dual-energy X-ray absorptiometry scans produce heterogeneous local bone mineral density changes and are not recommended to evaluate bone disease in these patients. Biomarkers (eg, N- and C-terminal telopeptides of type I collagen) have been used to assess bone metabolism balance (BMB; ie, the difference between bone formation and resorption) in MM prior and subsequent to specific therapies, however, consensus is still lacking and their clinical utility is uncertain. Calcium in nature consists of six isotopes, and the relative abundance of the isotopes varies measurably. The strength of molecular bonds depends on atomic weight of the participating atoms. Calcium (Ca) containing compounds react at different rates depending on atomic mass. Bone formation favors lighter isotopes of Ca, depleting soft tissue of light Ca isotopes, while bone resorption releases this isotopically light Ca back into soft tissue with little or no selectivity. As a result of this difference in isotope fractionation, Ca isotopic composition in soft tissue should shift to heavier Ca isotope values in positive BMB and lighter values in negative BMB. In order to identify whether Ca isotopic composition can be used as a marker of myeloma-induced bone disease, we first set out to determine its association with MM disease activity. Using multiple collector inductively coupled plasma mass spectrometry, we determined the Ca isotopic composition in 108 peripheral blood samples from 54 patients with monoclonal gammopathies. Ca isotopic composition was determined as the ratio between the naturally occurring 44Ca and 42Ca isotopes (δ44/42Ca) relative to a standard in parts per ten thousand units, as previously described by Morgan et al. Disease activity was determined at the time of δ44/42Ca determination by assessing disease status and response to treatment, as described by the International Myeloma Working Group uniform response criteria, defining progressive or relapsed disease as active disease, and stable or responsive disease as non-active. Categorical variables were analyzed using chi squared or Fisher’s exact test, interval variables were analyzed using a one-tailed t-test. A repeated measures logistic regression model was developed using a cross-sectional time-series generalized estimating equation. All statistical analysis was done using Stata/SE 12.0. Fifty-four adult patients (61% male) diagnosed with monoclonal gammopathy, ranging from MGUS (n=1) to SMM (n=4) to MM (n=49), were assessed at different time points, with 7 patients being assessed once, 41 were assessed twice, 5 were assessed 3 times, while 1 patient was assessed 4 times. Mean age at the time of first assessment was 66, ranging from 45 to 84. Mean δ44/42Ca was statistically lower in the active disease group as compared to the non-active group (-0.7536 vs -0.6564, p=0.0466). In a statistically significant repeated measurement logistic regression model (p= 0.0239), δ44/42Ca is associated with active disease (OR=0. 054, p=0.031, 95% CI=0.004-0.765) after adjusting for age, gender, presence of anemia, serum creatinine, free light chain ratio, current bisphosphonate and current anti-myeloma therapy. A lower δ44/42Ca in the active disease group might suggest a link between a more intense level of bone resorption and myeloma activity. Ca isotopic composition can become part of the clinician’s arsenal to determine disease status in a patient with MM. In order to further characterize δ44/42Ca to specifically infer myeloma-induced bone disease activity, further studies that include serum biomarkers and dynamic imaging should be performed. Disclosures: Gordon: Arizona State University: “Application of Ca isotope analysis to the early detection of metastatic cancer” (AzTE reference number M13-117) Patents & Royalties; Arizona State University: “Isotopic biomarkers for rapid assessment of bone mineral balance in biomedical applications” (US Application #PCT/US2011/039780; AzTE reference number M10-102L), “Isotopic biomarkers for rapid assessment of bone mineral balance in biomedical applications” (US Application #PCT/US2011/039780; AzTE reference number M10-102L) Patents & Royalties. Skulan:AZTE: “Application of Ca isotope analysis to the early detection of metastatic cancer” (AzTE reference number M13-117) Patents & Royalties; AZTE: “Isotopic biomarkers for rapid assessment of bone mineral balance in biomedical applications” (US Application #PCT/US2011/039780; AzTE reference number M10-102L), “Isotopic biomarkers for rapid assessment of bone mineral balance in biomedical applications” (US Application #PCT/US2011/039780; AzTE reference number M10-102L) Patents & Royalties. Anbar:Arizona State University: “Isotopic biomarkers for rapid assessment of bone mineral balance in biomedical applications” (US Application #PCT/US2011/039780; AzTE reference number M10-102L), “Isotopic biomarkers for rapid assessment of bone mineral balance in biomedical applications” (US Application #PCT/US2011/039780; AzTE reference number M10-102L) Patents & Royalties; Arizona State University: “Application of Ca isotope analysis to the early detection of metastatic cancer” (AzTE reference number M13-117) Patents & Royalties. Fonseca:AMGEN: Consultancy; Millennium: Consultancy; Binding Site: Consultancy; Onyx: Consultancy, Research Funding; Lilly: Consultancy; BMS: Consultancy; Genzyme: Consultancy; Celgene: Consultancy; Medtronic: Consultancy; Otsuka: Consultancy; Cylene: Research Funding; Prognostication of MM based on genetic categorization of the disease: Patents & Royalties.
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Oi, Takao, Kunihiko Sato y Kazuki Umemoto. "Oxygen and Hydrogen Isotopic Preference in Hydration Spheres of Magnesium and Calcium Ions". Zeitschrift für Naturforschung A 68, n.º 5 (1 de mayo de 2013): 362–70. http://dx.doi.org/10.5560/zna.2012-0122.
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Molecular orbital calculations were performed to estimate the 18O/16O and D/H isotopic reduced partition function ratios (rpfrs) of water molecules around magnesium and calcium ions. As model for water molecules in the ith hydration sphere of the cation in aqueous solutions containing that cation, we considered water molecules in the ith hydration sphere that were surrounded by water molecules in the (i+1)th hydration sphere in clusters, M2+(H2O)n (M = Mg or Ca; n up to 100). The calculations indicated that the decreasing order of the 18O preference over 16O in the primary hydration sphere is Mg2+ > Ca2+ > bulk water. That is, water molecules in the primary hydration spheres of the Mg2+ and Ca2+ ions are expected to be enriched in the heavier isotope of oxygen relative to water molecules in bulk, and the degree of the enrichment is larger for the Mg2+ ion than for the Ca2+ ion. No such preference was observed for hydrogen isotopes in any hydration sphere or for oxygen isotopes in the secondary and outer hydration spheres.
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Schwarzschild, Bertram M. "Weighing exotic calcium isotopes". Physics Today 66, n.º 9 (septiembre de 2013): 15–17. http://dx.doi.org/10.1063/pt.3.2104.
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Amsellem, Elsa, Frédéric Moynier, Hervé Bertrand, Amaury Bouyon, João Mata, Sebastian Tappe y James M. D. Day. "Calcium isotopic evidence for the mantle sources of carbonatites". Science Advances 6, n.º 23 (junio de 2020): eaba3269. http://dx.doi.org/10.1126/sciadv.aba3269.
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The origin of carbonatites—igneous rocks with more than 50% of carbonate minerals—and whether they originate from a primary mantle source or from recycling of surface materials are still debated. Calcium isotopes have the potential to resolve the origin of carbonatites, since marine carbonates are enriched in the lighter isotopes of Ca compared to the mantle. Here, we report the Ca isotopic compositions for 74 carbonatites and associated silicate rocks from continental and oceanic settings, spanning from 3 billion years ago to the present day, together with O and C isotopic ratios for 37 samples. Calcium-, Mg-, and Fe-rich carbonatites have isotopically lighter Ca than mantle-derived rocks such as basalts and fall within the range of isotopically light Ca from ancient marine carbonates. This signature reflects the composition of the source, which is isotopically light and is consistent with recycling of surface carbonate materials into the mantle.
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Kumar, P. V. Kiran, M. Sankari y M. V. Suryanarayana. "Isotope selective near-resonant two-photon ionization of calcium isotopes". Journal of Physics D: Applied Physics 40, n.º 1 (15 de diciembre de 2006): 288–93. http://dx.doi.org/10.1088/0022-3727/40/1/028.
Texto completoTesis sobre el tema "Isotopes calcium"
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Valdes, Maria. "Geochemistry and Cosmochemistry of Calcium Stable Isotopes". Doctoral thesis, Universite Libre de Bruxelles, 2018. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/276866.
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Calcium (Ca) is the fifth most abundant element in the rocky planets. As a lithophile, refractory element, Ca does not partition into planetary cores nor is it volatilized during planetary accretion. These characteristics make Ca ideal for investigating the earliest stages of planetary formation and the subsequent chemical evolution of planetary mantles and crusts. This thesis presents observations of and explores the mechanisms involved in high-temperature mass-dependent Ca isotope fractionation in terrestrial, lunar, and meteoritic material. Chapter 1 reports Ca isotope fractionation among a co-genetic suite of samples from the Guelb el Azib ultramafic-mafic-anorthosite complex, which represents the fractional crystallization sequence of a terrestrial igneous magma chamber. The measurements imply that Ca isotope fractionation in an evolving crystallizing magma is mineralogically controlled and that the degree of fractionation can vary according to the Ca composition of the residual magma. Chapter 2 investigates ureilites, a distinctive group of achondritic meteorites, widely regarded to be mantle remnants of a disrupted asteroidal parent body. To date, it is not clear which of their features were inherited from the original chondritic body and which were created during post-accretionary igneous processes such as partial melting. This chapter presents evidence that partial melting on the ureilite parent body is responsible for two such ambiguous characteristics, Ca isotopic and magnesium number (MgDoctorat en Sciences
info:eu-repo/semantics/nonPublished
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Tacail, Théo. "Physiologie isotopique du Calcium chez les mammifères". Thesis, Lyon, 2017. http://www.theses.fr/2017LYSEN071/document.
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L’environnement et la physiologie déterminent les compositions isotopiques du Ca de l’organisme des vertébrés et des mammifères en particulier. Ces constats ont permis de dégager des applications possibles de l’étude des isotopes du Ca, en biologie médicale pour le suivi de l’équilibre osseux chez les mammifères et en (paléo-)écologie pour l’étude des régimes alimentaires actuels et passés des vertébrés. Ces applications sont tributaires d’une meilleure compréhension fondamentale des causes de ces variations. Cette thèse a pour but de déterminer les principales causes de variabilité des compositions isotopiques du Ca chez les mammifères et l’humain. Un protocole d’analyse en solution par MC-ICP-MS est d’abord présenté puis deux méthodes d’échantillonnage sont comparées afin de réaliser des mesures de résolution spatiale accrue dans les tissus minéralisés. L’influence des sources alimentaires de Ca est ensuite discutée. La composition isotopique de l’alimentation humaine est variable du fait des compositions diverses des sources primaires de Ca et dépend particulièrement des proportions de produits laitiers dans l’alimentation. Il est démontré que les transitions nutritionnelles précoces, comme le sevrage du lait maternel, peuvent être tracées par les compositions de l’émail des dents de lait humaines. Les mécanismes des fractionnements isotopiques sont discutés sur la base d’observations chez l’humain et l’animal. Un modèle mathématique permet de dégager des mécanismes expliquant la distribution des isotopes du Ca à travers les tissus et les fluides de l’organisme et met en lumière le rôle prépondérant du rein dans la détermination de la composition isotopique de l’osEnvironment influences the isotope compositions of body Ca and vertebrate physiology affects these compositions in turn. These observations have allowed recognition of possible applications for Ca isotopes, in the field of medical biology, with the assessment of bone mineral balance in human, and in (palaeo-)ecology for the study of past and present day diets in vertebrates. These applications depend on a better fundamental understanding of causes for these variations. This thesis aims at identifying the main mechanisms responsible for variability of Ca isotope compositions in mammals and human. A solution mode analysis protocol was first developed for MC-ICP-MS. Two methods for microsampling of tooth enamel were then compared in order to increase spatial resolution of mineralized tissues analysis. The influence of dietary Ca sources has been discussed. Isotope composition of human diet is variable because of the diversity of Ca primary sources but also due to variations in dairy products proportions in diet. Early dietary transitions, such as weaning, can be studied using the Ca isotope compositions of human deciduous tooth enamel.Based on observations in human and other mammals, the mechanisms responsible for Ca isotope fractionations are discussed. A mathematical model was developed, allowing the identification of some mechanisms responsible for Ca isotope distribution across organism reservoirs, and sheds light on the crucial role of kidney in determination of bone isotope compositions
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Ramos, João Pedro Fernandes. "Effect of calcium oxide microstructure on the diffusion of isotopes". Master's thesis, Universidade de Aveiro, 2012. http://hdl.handle.net/10773/8187.
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Mestrado em Ciência e Engenharia de MateriaisCalcium oxide (CaO) powder targets have been successfully used at CERN-ISOLDE to produce neutron deficient exotic argon and carbon isotopes under proton irradiation at high temperatures (>1000oC). These targets outperform the other related targets for the production of the same beams. However, they presented either slow release rates (yields) from the beginning or a rapid decrease over time. This problem was believed to come from the target microstructure degradation, justifying the material investigation. In order to do so, the synthesis, reactivity in ambient air and sintering kinetics of CaO were studied, through surface area determination by N2 adsorption, X-ray diffraction for crystalline phase identification and crystallite size determination, and scanning and transmission electron microscopy to investigate the microstructure. The synthesis studies revealed that a nanometric material is obtained from the decarbonation of CaCO3 in vacuum at temperatures higher than 550oC, which is very reactive in air. This reactivity was studied, and it was observed that the CaO powder microstructure is changed through the reaction with air (hydration and carbonation of the oxide) and that this change is not completely reversible after thermal decomposition of the reaction products. Therefore, special care was taken in the target handling at CERN-ISOLDE. From the sintering kinetics, studied in the range of 1000-1200oC, it was determined that this material’s microstructure degrades, with the reduction of the specific surface area and decrease of the powder porosity. At 1200oC, the specific surface area reduction is accentuated, reaching values of 50% of surface area reduction in 10h. These results suggest that the use of high temperatures, equal or higher than 1000oC must be avoided, if the microstructural characteristics of the targets are to be preserved. At CERN-ISOLDE, selected conditions for synthesis, handling of the target and target operation temperatures were chosen, based on the previous material research, and the obtained target material was tested under proton irradiation. From the online studies, the newly developed target proved to show better initial and stable over time release rates of almost all isotopes investigated and especially the exotic ones. These results are essentially due to the nanometric characteristics of the produced target and to the use of operation and handling conditions that decreased the degradation of the microstructural characteristics. Diffusion studies of Ar and Ne were also done in CaO through the application of a mathematical model, to the release curves of the respective isotopes at different temperatures, which enables the determination of the respective diffusion coefficients and activation energies.
Alvos de pós de oxido de cálcio (CaO) têm sido usados, com sucesso, no CERN-ISOLDE para produzir isótopos de Árgon (com défice de neutrões) e de carbono, sob irradiação com protões a alta temperatura (>1000oC). Estes alvos têm mostrado um desempenho superior a outros alvos usados para produzir os mesmos feixes. Contudo, apresentam baixas taxas de libertação de isótopos desde o início de operação ou uma redução rápida com o tempo. Suspeitou-se que este problema se devia à degradação da microestrutura do material, justificando a sua investigação. Assim, a síntese, reatividade em ar ambiente e a cinética de sinterização do CaO foram estudadas, nomeadamente através da determinação da área superficial especifica por adsorção de N2, difração de raios-X para identificação de fases e determinação do tamanho de cristalite e microscopia eletrónica de varrimento e transmissão para o estudo da microestrutura. Os estudos de síntese do CaO revelaram que um material nanométrico, e muito reativo em ar, é obtido através da descarbonatação do CaCO3 em vácuo a temperaturas superiores a 550oC. Esta reatividade foi estudada e observou-se que a microestrutura do pó de CaO é alterada por reação com o ar (hidratação e carbonatação do óxido) e que esta alteração não é totalmente reversível após decomposição térmica dos produtos de reação. Assim, foram tomados cuidados especiais no manuseamento dos alvos de CaO. Da cinética de sinterização, estudada na gama de 1000-1200oC, foi concluído que a microestrutura deste material se degrada com redução da área superficial específica e diminuição da porosidade do pó. A 1200oC, a redução da área superficial específica é acentuada, atingindo-se valores de 50% de redução em cerca de 10h. Estes resultados indicam que a utilização de temperaturas elevadas, iguais ou superiores a 1000oC, devem ser evitadas se se pretendem preservar as características microestruturais dos alvos. No CERN-ISOLDE, as condições de síntese, de manuseamento do material e temperatura de operação do alvo foram escolhidas, com base nos estudos anteriores, e o material resultante foi testado sobre irradiação de protões. Dos estudos online, o alvo desenvolvido provou ter melhores taxas de libertação iniciais e que se mantêm ao longo do tempo de libertação, comparativamente a outros alvos de CaO previamente usados no CERN-ISOLDE. Isto verificou-se em praticamente todos os isótopos estudados, especialmente nos exóticos. Estes resultados foram atribuídos às caraterísticas nanométricas do alvo produzido e à utilização de condições de manuseamento e de operação, tais que a degradação das características microestruturais do alvo é reduzida. Estudos de difusão de Árgon e Néon foram feitos no CaO através da aplicação de um modelo matemático às curvas de libertação dos respetivos isótopos a diferentes temperaturas de operação, que permitiram a determinação dos respetivos coeficientes de difusão e energias de ativação.
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Schmitt, Anne-Désirée. "Les isotopes du calcium : Développements analytiques.Application au bilan océanique présent et passé". Université Louis Pasteur (Strasbourg) (1971-2008), 2003. http://www.theses.fr/2003STR13077.
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Le calcium est le cinquième élément le plus abondant de la Terre silicatée. Son intérêt découle de son abondance dans la croûte terrestre et de l'existence d'une grande quantité de minéraux le contenant. Un fractionnement maximum, dont les causes précises ne sont pas connues, de 1,3 par u. M. A a été mesuré à ce jour. Le travail réalisé durant ce doctorat s'intègre à ces nouvelles études sur les isotopes du Ca. Un protocole de mesure permettant de s'affranchir du fractionnement instrumental a tout d'abord été développé au Centre de Géochimie de la Surface. Après séparation chimique sur résine échangeuse d'ions, les compositions isotopiques en Ca ont été déterminées au spectromètre de masse à thermo-ionisation par une technique employant un double spike. L'expression des rapports isotopiques du Ca sous forme de delta requiert l'emploi d'un matériel de référence. Aucun standard international n'existant pour les isotopes du Ca, le standard carbonaté SRM 915a du NIST a été proposé. L'eau de mer, seul échantillon commun à la majorité des études antérieures, a été calibré en fonction de ce standard carbonaté et utilisé pour ce travail. Ce protocole a ensuite été appliqué à l'étude du bilan océanique du Ca. L'étude d'eaux continentales a permis de contraindre le flux de Ca arrivant aux océans. Il en résulte une variabilité limitée de d44Ca (0,5 ) à l'embouchure des grands fleuves et pour les eaux hydrothermales. Aucune relation n'a en outre été observée entre d44Ca et la lithologie ou le climat des bassins versants étudiés. Ceci a permis de calculer une composition isotopique moyenne en Ca arrivant aux océans égale à -1,1 ± 0,2 et de suggérer sa constance au cours du temps. Il résulte de cette valeur que l'océan actuel est à l'état stationnaire par rapport aux isotopes du calcium. L'étude du d44Ca de phosphates marins du Miocène et du Pléistocène, qui reflètent la paléo-variation de l'eau de mer au cours du temps, a montré que cela n'a pas toujours été le cas par le passé. Ainsi, à 22 Ma, une incursion du d44Ca vers des valeurs plus positives suggère que l'intensité des flux entrants et sortants a varié, mais non leur signature isotopiqueFirst, a measurement protocol was developed at the Centre de Géochimie de la Surface to avoid instrumental fractionation. After chemical separation on ion exchanging resins, the Ca isotopic compositions were measured on a thermo-ionisation mass spectrometer, using a double-spike technique. The Ca isotopic ratios were expressed in a delta notation. To do this, a reference material is needed. No international standard presently exists for Ca isotopes. For that reason, we proposed to use the SRM 915a carbonaceous standard from the NIST. Seawater, the only common sample of most of previous studies has also been used: it was calibrated against the carbonaceous standard and used in present study. This protocol was then applied to study the Ca oceanic budget. The isotope data of continental waters allowed to constrain the Ca flux to the ocean. A limited variability of d44Ca (0. 5 ) was recorded at the outlet of main rivers or for hydrothermal vents. Moreover, no relationship was observed between d44Ca and the lithology or the climate of the studied watersheds. This allowed to determine the mean Ca isotopic composition of the Ca flux to the ocean (-1. 1 ± 0. 2 ) and to suggest that this value remains rather constant through time. A consequence of this value is that present-day seawater is at steady-state with regard to Ca isotopes. The d44Ca study of marine phosphates from Miocene and Pleistocene, which reflect the paleo-seawater variations through time, has shown that this was not necessarily the case in the past. At 22 Ma, a deviation in d44Ca through more positive values suggests that the intensity of the incoming and outcoming fluxes changed, but not their isotopic composition
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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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Perez, Fernandez Andrea. "Etude expérimentale sur l'échange isotopique dans le système eau-roches carbonatées". Thesis, Toulouse 3, 2017. http://www.theses.fr/2017TOU30398.
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Les signatures isotopiques des minéraux carbonatés sont utilisées pour caractériser de nombreux processus géochimiques. Cette thèse a pour but de déterminer les vitesses auxquelles ces signatures isotopiques peuvent être altérées lors des interactions entre les fluides et les minéraux. A cette fin, une série d'études expérimentales a été conduite avec la dolomite (CaMg(CO3)2), la magnésite (MgCO3) et la calcite (CaCO3). On a mesuré l'évolution temporelle des compositions isotopiques de Ca et Mg pendant une série d'expériences de dissolution en réacteur fermé de la dolomite à des températures de 50°C à 126°C. A T < 120°C la composition isotopique du calcium dans la phase fluide est identique à celle de la dolomite initiale, mais au-delà de cette température, la signature isotopique du calcium dans le fluide (delta(44/42)Ca fluid) après 4 semaines était 0.6±0.1‰ plus lourde que l'originale. En revanche, le rapport delta(26/24)Mg du fluide reste égal à celui de la dolomite à toutes les températures étudiées. Ces résultats indiquent un double transfert de calcium vers et depuis la structure de la dolomite à T > 120°C. En outre, ces résultats suggèrent que la difficulté de la dolomite à précipiter à température ambiante doit être la conséquence de l'incapacité de Mg à s'incorporer dans la structure du minéral. Dans une autre étude on a conduit des expériences de dissolution de la magnésite à 25°C en solution aqueuses pour différents pH et pression de CO2. On a trouvé que la composition isotopique du fluide à proximité de l'équilibre chimique était différente de celle du solide, ce qui reflète un double transfert de Mg en direction et hors du minéral à température ambiante. Cependant, un seul mécanisme de fractionnement ne peut expliquer le comportement isotopique de Mg observé. La dernière partie de ce travail, consacrée au fractionnement isotopique du carbone dans le système calcite-eau, montre une évolution du fractionnement isotopique de cet élément vers le fractionnement isotopique à l'équilibre d'une durée d'une année après l'atteinte de l'équilibre chimique entre la calcite et l'eau. Les vitesses de rééquilibrage des isotopes de carbone sont ainsi quatre ordres de grandeurs plus lentes que la vitesse d'équilibrage de la calcite avec la solution. Ceci suggère que l'étape limitante dans le processus de rééquilibrage des isotopes du carbone est le transport de cet élément dans le cristal après l'échange isotopique à la surface de ce dernier. Les résultats de cette thèse indiquent que la signature isotopique de Mg, Ca et C des carbonates n'est pas invariante à l'échelle des temps géologiques et qu'elle peut être altérée durant l'interaction de ces minéraux avec l'eau. Ainsi, la préservation des signatures isotopiques des carbonates requiert d'une faible perméabilité des roches ou bien quelque mécanisme inhibant les échanges des métaux et du carbone à la surface des cristauxThe isotopic signatures of carbonate minerals have been applied to illuminate a plethora of natural geochemical processes. This thesis is aimed to assess the rates and or conditions at which such isotope signatures might be altered by fluid-mineral interaction through a series of systematic experimental studies performed with dolomite (CaMg(CO3)2) magnesite (MgCO3) and calcite (Ca-CO3). Ca and Mg isotopic compositions were measured as a function of time during closed-system stoichiometric dolomite dissolution experiments at 50 to 126°C. Although identical to that of the original dolomite at low temperatures, at temperatures >120 °C, the calcium isotopic signature of fluid phase (delta(44/42)Ca fluid) became 0.6±0.1‰ higher than that of the dissolving dolomite over a 4-week period. In contrast, the delta(26/24)Mg fluid, remained equal to that of the dolo-mite both at low and high temperatures. This set of experiments evidences the two-way transfer of calcium in and out of the dolomite structure at elevated temperatures. The results suggest that the inhability of dolomite to precipitate at these conditions is due to the difficulty of Mg to be reincorporated in the dolomite structure. In a follow-up study, magnesite was dissolved at 25°C in the presence of fluids with distinct pH and CO2 pressures. The isotopic compositions of the fluid differed from that of the solid at near-to chemical equilibrium indicating the two-way transfer of magnesium into this mineral at ambient temperatures. A single fractionation mechanism cannot explain the distinct Mg isotope behaviors observed. Further work on carbon isotope exchanges in the calcite water system shows a slow by steady evolution of the carbon isotopic composition towards the accepted equilibrium fractionation factor over the course of nearly year-long experiments after the system had attained bulk chemical equilibrium. Carbon isotope reequilibration rates were found to be approximately four orders of magnitude slower than that of bulk calcite dissolution, suggesting that the rate limiting step to the carbon isotope reequilibration process is the transport of carbon into and out of the bulk mineral after it has exchanged on the surface. The results of this thesis suggest that the Mg, Ca and C isotopic signatures in carbonate minerals are not invariant over geological time-frames and can be readily altered by water-mineral interaction. Such results indicate that the preservation of carbonate mineral signatures require low permeability rock formations or some inhibitory mechanism limiting metal and carbon exchange
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Brazier, Jean-Michel. "Rôle des phases minérales des sols en tant que réservoirs de nutriments : approche expérimentale (abiotique), en milieu naturel et multi-isotopique (isotopes stables Ca-Sr)". Thesis, Strasbourg, 2018. http://www.theses.fr/2018STRAH005/document.
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Ce travail de thèse a appréhendé les mécanismes de stockage/libération, d’un point de vue élémentaire et isotopique, du calcium (Ca) et du strontium (Sr) sur ou dans des phases minérales communes des sols (minéraux primaires, minéraux argileux, oxy-hydroxydes, carbonate pédogénétiques). Une méthode de mesure robuste du δ88Sr a dû être développée et validée par la mesure de matériaux de références internationaux, pour la plupart jamais mesuré dans la littérature. Les résultats montrent que l’adsorption du Ca sur des minéraux phyllosilicatés génère un fractionnement isotopique par prélèvement préférentiel de l’isotope léger (40Ca) dans nos conditions expérimentales lorsque les minéraux possèdent une charge structurale et une surface spécifique importante et/ou un espace interfoliaire ouvert à l’adsorption de cations hydratés. Une étude sur des rhizolithes en milieu naturel a mis en avant que l’utilisation des isotopes du Ca et du Sr permet un traçage de source et de mécanismes efficaces dans les thématiques touchant au stockage de ces deux éléments dans les solsThis PhD thesis examined the mechanisms of storage and release, from and elementary and isotopically point of view, of calcium (Ca) and strontium (Sr) onto or into mineral phases commonly encountered within soils (primary minerals, clay minerals, oxy-hydroxides, pedogenic carbonate). A robust δ88Sr measurements method had to be developed in the laboratory and validated by the measurement of international reference materials, mostly never measured in the literature. The results of this work show that Ca adsorption onto phyllosilicate minerals generates a quantifiable isotopic fractionation by preferential uptake of the light isotope (40Ca) under our experimental conditions when the minerals have a significant structural charge and specific surface area and/or an interlayer space open to hydrated cations adsorption. A study on rhizoliths in natural environment has also highlighted that the combination of Ca and Sr isotopes allows an effective tracing of sources and mechanisms in the problematic related to the storage of these two elements within soils
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Blättler, Clara L. "Applications of calcium isotopes in marine carbonates in the Recent and Phanerozoic". Thesis, University of Oxford, 2012. http://ora.ox.ac.uk/objects/uuid:9f2ce280-c7b9-43cc-8aaf-4aaac058d350.
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The applications of calcium-isotope measurements in marine carbonates are explored in several different contexts within this thesis. As a record of global ion fluxes, seawater calcium-isotope ratios can be used as tracers for large weathering imbalances, which develop as a feedback system in response to intervals of climate change. This approach provides valuable constraints on the complex climatic and oceanographic phenomena known as the Oceanic Anoxic Events. Over much longer timescales, the calcium-isotope ratio of seawater is influenced by steady-state processes that reflect the evolution of seawater chemistry. To understand these influences, the modern calcium-isotope budget is assessed quantitatively using a compilation of marine carbonate samples, revealing several distinctive components of the carbonate burial sink that can affect the steady-state balance of the calcium cycle. Changes in the major ion composition of seawater and in the organisms that contribute to sedimentary carbonate burial are shown to contribute significantly to the geological record of seawater calcium-isotope ratios. The importance of skeletal carbonate in the calcium cycle leads to another application of calcium isotopes towards understanding biomineralization. This large and complex topic is approached with calcium-isotope data from two unique growth experiments that constrain some of the mechanisms by which biogenic aragonite acquires its geochemical signatures. This range of topics presents a diverse, but by no means exclusive, sample of the topics that are accessible for investigation through calcium-isotope analysis. The potential of this isotopic tool is demonstrated by the breadth of environments and timescales represented in this work.
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Griffith, Elizabeth Morris. "Seawater calcium isotopes and the cenozoic carbonate depositional history of the oceans /". May be available electronically:, 2008. http://proquest.umi.com/login?COPT=REJTPTU1MTUmSU5UPTAmVkVSPTI=&clientId=12498.
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Drouet, Thomas. "Etude de l'origine du calcium dans les écosystèmes forestiers par les méthodes de géochimie et de dendrochime isotopiques du strontium". Doctoral thesis, Universite Libre de Bruxelles, 2005. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/210940.
Texto completoLibros sobre el tema "Isotopes calcium"
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M, Imamura y United States. National Aeronautics and Space Administration., eds. Measurements of proton-induced production cross sections for ³⁶Cl from Ca and K. [Washington, DC: National Aeronautics and Space Administration, 1998.
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Gussone, Nikolaus, Anne-Desiree Schmitt, Alexander Heuser, Frank Wombacher, Martin Dietzel, Edward Tipper y Martin Schiller. Calcium Stable Isotope Geochemistry. Berlin, Heidelberg: Springer Berlin Heidelberg, 2016. http://dx.doi.org/10.1007/978-3-540-68953-9.
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Köhler-Langes, Florian. The Electron Mass and Calcium Isotope Shifts. Cham: Springer International Publishing, 2017. http://dx.doi.org/10.1007/978-3-319-50877-1.
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K, Kyser T., United States. Dept. of Energy. Nevada Operations Office. y Geological Survey (U.S.), eds. Uranium, thorium isotopic analyses and uranium-series ages of calcite and opal, and stable isotopic compositions of calcite from drill cores UE25a#1, USW G-2 and USW G-3/GU-3, Yucca Mountain, Nevada. Denver, Colo: U.S. Dept. of the Interior, Geological Survey, 1985.
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K, Kyser T., United States. Dept. of Energy. Nevada Operations Office. y Geological Survey (U.S.), eds. Uranium, thorium isotopic analyses and uranium-series ages of calcite and opal, and stable isotopic compositions of calcite from drill cores UE25a#1, USW G-2 and USW G-3/GU-3, Yucca Mountain, Nevada. Denver, Colo: U.S. Dept. of the Interior, Geological Survey, 1985.
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Griffith, Elizabeth y Matthew Fantle. Calcium Isotopes. Cambridge University Press, 2020.
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Griffith, Elizabeth y Matthew Fantle. Calcium Isotopes. Cambridge University Press, 2021.
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Griffith, Elizabeth M. y Matthew S. Fantle. Calcium Isotopes. Cambridge University Press, 2020.
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Schmitt, Anne-Desirée, Nikolaus Gussone, Florian Böhm, Alexander Heuser y Frank Wombacher. Calcium and Magnesium Stable Isotope Chemistry. Springer Berlin / Heidelberg, 2016.
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Ellam, Rob. 10. Probing the Earth with isotopes. Oxford University Press, 2016. http://dx.doi.org/10.1093/actrade/9780198723622.003.0010.
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‘Probing the Earth with isotopes’ shows how, using isotopes, we have come to understand the structure and behaviour of the Earth. The outer few tens of kilometres are divided into continental and oceanic crust. Below the crust, the sub-surface is divided into the mantle and the core. From the base of the crust to about 2,800 km depth, the Earth is rocky and composed of minerals like olivine and pyroxene that are rich in magnesium, iron, and calcium. From about 2,800 km to about 5,100 km depth the outer core is liquid. The remaining 1,200 km or so to the centre of the Earth is solid metal.
Capítulos de libros sobre el tema "Isotopes calcium"
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Farkaš, Juraj. "Calcium Isotopes". En Encyclopedia of Earth Sciences Series, 1–6. Cham: Springer International Publishing, 2016. http://dx.doi.org/10.1007/978-3-319-39193-9_237-1.
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Farkaš, Juraj. "Calcium Isotopes". En Encyclopedia of Earth Sciences Series, 181–86. Cham: Springer International Publishing, 2018. http://dx.doi.org/10.1007/978-3-319-39312-4_237.
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Heuser, Alexander. "Biomedical Application of Ca Stable Isotopes". En Calcium Stable Isotope Geochemistry, 247–60. Berlin, Heidelberg: Springer Berlin Heidelberg, 2016. http://dx.doi.org/10.1007/978-3-540-68953-9_8.
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Nielsen, Laura C., Jennifer L. Druhan, Wenbo Yang, Shaun T. Brown y Donald J. DePaolo. "Calcium Isotopes as Tracers of Biogeochemical Processes". En Advances in Isotope Geochemistry, 105–24. Berlin, Heidelberg: Springer Berlin Heidelberg, 2011. http://dx.doi.org/10.1007/978-3-642-10637-8_7.
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Salazar-García, Domingo C., Christina Warinner, Jelmer W. Eerkens y Amanda G. Henry. "The Potential of Dental Calculus as a Novel Source of Biological Isotopic Data". En Exploring Human Behavior Through Isotope Analysis, 125–52. Cham: Springer International Publishing, 2023. http://dx.doi.org/10.1007/978-3-031-32268-6_6.
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AbstractStable isotope analysis has become an essential tool in investigations of ancient migration and paleodietary reconstruction. Because the biogeochemistry of bone collagen and apatite is well known, current methods rely almost exclusively on analyses of bones and teeth; however, dental calculus represents a potentially additional biological source of isotopic data from ancient skeletons. Dental calculus is a mineralized bacterial biofilm that forms on the surfaces of teeth. Sampling dental calculus does not damage the dentition and thus can be used in cases where it is not possible to perform destructive analyses of conventional mineralized tissues. Like bone and dentine, dental calculus contains both inorganic and organic components, allowing measurement of C, N, O, H, and Sr isotopes. Additionally, dental calculus forms as serial, non-remodeling laminar accretions on the tooth surface, opening up the possibility of analyzing discrete time points during the lifetime of an individual. However, as a microbial biofilm and not a human tissue, the biochemistry of dental calculus is complex, containing multiple calcium phosphate mineral phases, organic and inorganic food remains, hundreds of human and bacterial proteins, and diverse biomolecules from thousands of endogenous bacterial taxa. Isotopic investigation of dental calculus is still in its infancy, and many questions remain regarding its formation and processes of diagenesis. This chapter (1) reviews the unique advantages presented by dental calculus as a novel source of biological isotopic data, (2) critically evaluates published isotopic studies of dental calculus, and (3) explores the current challenges of dental calculus stable isotope analysis through a case study of an Ancient Puebloan Basketmaker II population from the American Southwest.
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DePaolo, Donald J. "8. Calcium Isotopic Variations Produced by Biological, Kinetic, Radiogenic and Nucleosynthetic Processes". En Geochemistry of Non-Traditional Stable Isotopes, editado por Clark M. Johnson, Brian L. Beard y Francis Albarède, 255–88. Berlin, Boston: De Gruyter, 2004. http://dx.doi.org/10.1515/9781501509360-011.
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Floren, T. y E. Werner. "Assessment of Stable Isotopes of Calcium for the Measurement of Intestinal Calcium Absorption". En Generalized Bone Diseases, 155–61. Berlin, Heidelberg: Springer Berlin Heidelberg, 1987. http://dx.doi.org/10.1007/978-3-642-73346-8_14.
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Pfahler, V., J. Adu-Gyamfi, A. Watzinger y F. Tamburini. "Modifications and Issues During Purification". En Oxygen Isotopes of Inorganic Phosphate in Environmental Samples, 45–49. Cham: Springer International Publishing, 2022. http://dx.doi.org/10.1007/978-3-030-97497-8_4.
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AbstractDepending on the extract, it is necessary to modify the purification protocol slightly. Each sample is different and despite a thorough testing of the purification protocol, issues might occur. The three modifications suggested include (1) adjustments in pH, (2) magnesium ammonium phosphate (MAP) precipitation and (3) reductions, prior to A1, of cations like iron (Fe), silica (Si) and calcium (Ca) which could cause interferences during the purification process. Some of the major issues often encountered are (1) no APM precipitation due to the presence of high carbonate concentrations, (2) the presence of high organic matter that requires additional steps in the protocol, (3) crystals not dissolving and (4) discoloration of solution.
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Jin, Meng y Dong Feng. "Non-traditional Stable Isotope Geochemistry of Seep Deposits". En South China Sea Seeps, 171–87. Singapore: Springer Nature Singapore, 2023. http://dx.doi.org/10.1007/978-981-99-1494-4_10.
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AbstractNon-traditional stable isotope geochemistry is a useful tool for revealing element migration, transformation and circulation in geological processes. A series of biogeochemical processes result in special and variable sedimentary environments in seep systems. Many elements are impacted and involved in different biogeochemical processes in seep systems, especially the formation of authigenic minerals, making seep deposits archives for studying elemental and isotopic behaviors in natural environments. Iron (Fe) and molybdenum (Mo) are involved in the formation of pyrite, and magnesium (Mg) and calcium (Ca) are closely related to the precipitation of authigenic carbonate. Research on the Fe, Mo, Mg and Ca isotopic compositions of different seep deposits from the South China Sea has been conducted in recent years. Preliminary studies have provided new insights into the mechanisms of isotopic fractionation and element cycling during early diagenesis. In this chapter, we provide an overview of the current understanding of the Fe, Mo, Mg and Ca isotope geochemistry of seep deposits from the South China Sea, targeting authigenic minerals, sediments and pore fluids.
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Dainty, Jack R. y Tom E. Fox. "Modeling in Nutrition. The Metabolism of Selenium, Copper, Zinc and Calcium Using Stable Isotopes in Humans". En Handbook of Elemental Speciation II - Species in the Environment, Food, Medicine and Occupational Health, 690–712. Chichester, UK: John Wiley & Sons, Ltd, 2005. http://dx.doi.org/10.1002/0470856009.ch3b.
Texto completoActas de conferencias sobre el tema "Isotopes calcium"
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Nielsen Lammers, Laura y Jennifer Mills. "Insights into calcite growth inhibition mechanisms from calcium isotopes". En Goldschmidt2021. France: European Association of Geochemistry, 2021. http://dx.doi.org/10.7185/gold2021.5415.
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Smart, Katie, Sebastian Tappe, Alan Woodland, Chris Harris, Nikolaus Gussone y Antonio Simonetti. "Calcium isotopes in cratonic mantle eclogites". En Goldschmidt2021. France: European Association of Geochemistry, 2021. http://dx.doi.org/10.7185/gold2021.6051.
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Tanaka, U., H. Matsunishi, I. Morita y S. Urabe. "Isotope-selective ion-trapping and sympathetic cooling of rare calcium isotopes". En International Quantum Electronics Conference, 2005. IEEE, 2005. http://dx.doi.org/10.1109/iqec.2005.1560826.
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Hostettler, E., Jaime Barnes, John Lassiter, Aaron Satkoski, Besim Dragovic, Paul Starr y Ethan Baxter. "Calcium Isotopes as Fluid Tracers during Rodingtization". En Goldschmidt2022. France: European Association of Geochemistry, 2022. http://dx.doi.org/10.46427/gold2022.9652.
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Fantle, Matthew y Benjamin Barnes. "Calcium isotopes' place in the diagenetic toolbox". En Goldschmidt2021. France: European Association of Geochemistry, 2021. http://dx.doi.org/10.7185/gold2021.7789.
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Stefanini, A. M. "Fusion of calcium isotopes and of nearby systems". En NUCLEAR STRUCTURE AND DYNAMICS 2012. AIP, 2012. http://dx.doi.org/10.1063/1.4764261.
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Bushaw, B. A., F. Juston, W. Nörtershäuser, N. Trautmann, P. Voss-de-Haan y K. Wendt. "Ultratrace Analysis of Calcium with High Isotopic Selectivity by Resonance Ionization Mass Spectrometry". En Laser Applications to Chemical and Environmental Analysis. Washington, D.C.: Optica Publishing Group, 1996. http://dx.doi.org/10.1364/lacea.1996.lfb.7.
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Using resonance ionization mass spectrometric techniques (RIMS) for ultratrace analysis has a number of advantages over conventional techniques: 1. Extremely high sensitivity in the fg to ag range per sample is possible with the high cross sections for optical excitation. 2. Ultrahigh elemental and isotopic selectivity is achieved by the uniqueness of the optical resonance lines of individual elements and isotopes. 3. Background is strongly suppressed by subsequent mass spectrometry. Unfortunately, the application of the technique is complicated by the complexity of the experimental set-up, particularly the laser system, and hence is limited to a small number of research institutes so far.
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TARASOV, O. B., D. J. MORRISSEY, A. M. AMTHOR, L. BANDURA, T. BAUMANN, D. BAZIN, J. S. BERRYMAN et al. "PRODUCTION OF NEUTRON-RICH ISOTOPES IN THE CALCIUM REGION". En Proceedings of the International Symposium. WORLD SCIENTIFIC, 2013. http://dx.doi.org/10.1142/9789814508865_0037.
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Jones, David S., R. William Brothers y John A. Higgins. "CALCIUM ISOTOPES, SEAWATER DIAGENESIS, AND END ORDOVICIAN EARTH HISTORY". En GSA Annual Meeting in Denver, Colorado, USA - 2016. Geological Society of America, 2016. http://dx.doi.org/10.1130/abs/2016am-280549.
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Fu, Hairuo, Stein Jacobsen, Bjørn Larsen y Zachary Eriksen. "Calcium-isotopes as a robust tracer of magmatic differentiation". En Goldschmidt2022. France: European Association of Geochemistry, 2022. http://dx.doi.org/10.46427/gold2022.12513.
Texto completoInformes sobre el tema "Isotopes calcium"
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Scanlan, E. J., M. Leybourne, D. Layton-Matthews, A. Voinot y N. van Wagoner. Alkaline magmatism in the Selwyn Basin, Yukon: relationship to SEDEX mineralization. Natural Resources Canada/CMSS/Information Management, 2021. http://dx.doi.org/10.4095/328994.
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Several sedimentary exhalative (SEDEX) deposits have alkaline magmatism that is temporally and spatially associated to mineralization. This report outlines interim data from a study of potential linkages between magmatism and SEDEX mineralization in the Selwyn Basin, Yukon. This region is an ideal study site due to the close spatial and temporal relationships between SEDEX deposits and magmatism, particularly in the MacMillan Pass, where volcanic rocks have been drilled with mineralization at the Boundary deposit. Alkaline volcanic samples were analysed from the Anvil District, MacMillan Pass, Keno-Mayo and the Misty Creek Embayment in the Selwyn Basin to characterise volcanism and examine the relationship to mineralization. Textural and field relationships indicate a volatile-rich explosive eruptive volcanic system in the MacMillan Pass region in comparison to the Anvil District, which is typically effusive in nature. High proportions of calcite and ankerite in comparison to other minerals are present in the MacMillan system. Cathodoluminescence imaging reveals zoning and carbonate that displays different luminescent colours within the same sample, likely indicating multiple generations of carbonate precipitation. Barium contents are enriched in volcanic rocks throughout the Selwyn Basin, which is predominately hosted by hyalophane with rare barite and barytocalcite. Thallium is positively correlated with Ba, Rb, Cs, Mo, As, Sb and the calcite-chlorite-pyrite index and is negatively correlated with Cu. Anvil District samples display a trend towards depleted mid-ocean ridge mantle on a plot of Ce/Tl versus Th/Rb. Hydrothermal alteration has likely led to the removal of Tl from volcanic rocks in the region. Ongoing research involves: i) the analysis of Sr, Nd, Pb and Tl isotopes of volcanic samples; ii) differentiating magmatic from hydrothermal carbonate using O, C and Sr isotopes; iii) examining sources of Ba in the Selwyn Basin; iv) and constraining age relationships through U-Th-Pb geochronology.
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B.D. Marshall y K. Futa. STRONTIUM ISOTOPE EVOLUTION OF PORE WATER AND CALCITE IN THE TOPOPAH SPRING TUFF, YUCCA MOUNTAIN , NEVADA. Office of Scientific and Technical Information (OSTI), febrero de 2001. http://dx.doi.org/10.2172/860281.
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B.D. Marshall y J.F. Whelan. Isotope Geochemistry of Calcite Coatings and the Thermal History of the Unsaturated Zone at Yucca Mountain, Nevada. Office of Scientific and Technical Information (OSTI), julio de 2000. http://dx.doi.org/10.2172/840662.
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B. Peterman y R. Moscati. Calcite Fluid Inclusion, Paragenetic, and Oxygen Isotopic Records of Thermal Event(s) at Yucca Mountain, Nevada. Office of Scientific and Technical Information (OSTI), agosto de 2000. http://dx.doi.org/10.2172/840694.
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Kirby, Stefan M., J. Lucy Jordan, Janae Wallace, Nathan Payne y Christian Hardwick. Hydrogeology and Water Budget for Goshen Valley, Utah County, Utah. Utah Geological Survey, noviembre de 2022. http://dx.doi.org/10.34191/ss-171.
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Goshen Valley contains extensive areas of agriculture, significant wetlands, and several small municipalities, all of which rely on both groundwater and surface water. The objective of this study is to characterize the hydrogeology and groundwater conditions in Goshen Valley and calculate a water budget for the groundwater system. Based on the geologic and hydrologic data presented in this paper, we delineate three conceptual groundwater zones. Zones are delineated based on areas of shared hydrogeologic, geochemical, and potentiometric characteristics within the larger Goshen Valley. Groundwater in Goshen Valley resides primarily in the upper basin fill aquifer unit (UBFAU) and lower carbonate aquifer unit (LCAU) hydrostratigraphic units. Most wells in Goshen Valley are completed in the UBFAU, which covers much of the valley floor. The UBFAU is the upper part of the basin fill, which is generally less than 1500 feet thick in Goshen Valley. Important spring discharge at Goshen Warm Springs issues from the LCAU. Relatively impermeable volcanic rocks (VU) occur along much of the upland parts of the southern part of Goshen Valley. Large sections of the southwest part of the Goshen Valley basin boundary have limited potential for interbasin flow. Interbasin groundwater flow is likely at several locations including the Mosida Hills and northern parts of Long Ridge and Goshen Gap in areas underlain by LCAU. Depth to groundwater in Goshen Valley ranges from at or just below the land surface to greater than 400 feet. Groundwater is within 30 feet of the land surface near and north of Goshen, in areas of irrigated pastures and wetlands that extend east toward Long Ridge and Goshen Warm Springs, and to the north towards Genola. Groundwater movement is from upland parts of the study area toward the valley floor and Utah Lake. Long-term water-level change is evident across much of Goshen Valley, with the most significant decline present in conceptual zone 2 and the southern part of conceptual zone 1. The area of maximum groundwater-level decline—over 50 feet—is centered a few miles south of Elberta in conceptual zone 2. Groundwater in Goshen Valley spans a range of chemistries that include locally high total dissolved solids and elevated nitrate and arsenic concentrations and varies from calcium-bicarbonate to sodium-chloride-type waters. Overlap in chemistry exists in surface water samples from Currant Creek, the Highline Canal, and groundwater. Stable isotopes indicate that groundwater recharges from various locations that may include local recharge, from the East Tintic Mountains, or far-traveled groundwater recharged either in Cedar Valley or east of the study area along the Wasatch Range. Dissolved gas recharge temperatures support localized recharge outside of Goshen. Most groundwater samples in Goshen Valley are old, with limited evidence of recent groundwater recharge. An annual water budget based on components of recharge and discharge yields total recharge of 32,805 acre-ft/yr and total discharge of 35,750 acre-ft/yr. Most recharge is likely from interbasin flow and lesser amounts from precipitation and infiltration of surface water. Most discharge is from well water withdrawal with minor spring discharge and groundwater evapotranspiration. Water-budget components show discharge is greater than recharge by less than 3000 acreft/yr. This deficit or change in storage is manifested as longterm water-level decline in conceptual zone 2, and to a lesser degree, in conceptual zone 1. The primary driver of discharge in conceptual zone 2 is well withdrawal. Conceptual zone 3 is broadly in balance across the various sources of recharge and discharge, and up to 1830 acre-ft/yr of water may discharge from conceptual zone 3 into Utah Lake. Minimal groundwater likely flows to Utah Lake from zones 1 or 2.
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Kontak, D. J., S. Paradis, Z. Waller y M. Fayek. Petrographic, fluid inclusion, and secondary ion mass spectrometry stable isotopic (O, S) study of Mississippi Valley-type mineralization in British Columbia and Alberta. Natural Resources Canada/CMSS/Information Management, 2022. http://dx.doi.org/10.4095/327994.
Texto completoResumen
A comprehensive study of Mississippi Valley-type base-metal deposits across the Canadian Cordillera was done to compare and contrast their features. Extensive dissolution of host rocks is followed by multiple generations of dolomite cements from early, low-temperature, fine-grained to coarser, higher temperature types that overlap with Zn-Pb sulfide minerals; late-stage calcite occludes residual porosity. Dolomite is generally chemically stoichiometric, but ore-stage types are often rich in Fe (&lt;1.3 weight per cent FeO) with small sphalerite inclusions. Sphalerite-hosted fluid inclusions record ranges for homogenization temperatures (77-214°C) and fluid salinity (1-28 weight per cent equiv. NaCl±CaCl2). These data suggest fluid mixing with no single fluid type related to all sulfide mineralization. In situ secondary ion mass spectrometry (SIMS) generated delta-18OVSMOW values for carbonate minerals (13-33 permille) reflect dolomite and calcite formation involving several fluids (seawater, basinal, meteoric) over a large temperature range at varying fluid-rock ratios. Sphalerite and pyrite SIMS delta-34SVCDT values vary (8-33 permille) but in single settings have small ranges (&lt;2-3 permille) that suggest sulfur was reduced via thermochemical sulfate reduction from homogeneous sulfur reservoirs. Collectively, the data implicate several fluids in the mineralizing process and suggest mixing of a sulfur-poor, metal-bearing fluid with a metal-poor, sulfide-bearing fluid.
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Kingston, A. W. y O. H. Ardakani. Diagenetic fluid flow and hydrocarbon migration in the Montney Formation, British Columbia: fluid inclusion and stable isotope evidence. Natural Resources Canada/CMSS/Information Management, 2022. http://dx.doi.org/10.4095/330947.
Texto completoResumen
The Montney Formation in Alberta and British Columbia, Canada is an early Triassic siltstone currently in an active diagenetic environment at depths greater than 1,000 m, but with maximum burial depths potentially exceeding 5,000 m (Ness, 2001). It has undergone multiple phases of burial and uplift and there is strong evidence for multiple generations of hydrocarbon maturation/migration. Understanding the origin and history of diagenetic fluids within these systems helps to unravel the chemical changes that have occurred since deposition. Many cores taken near the deformation front display abundant calcite-filled fractures including vertical or sub-vertical, bedding plane parallel (beefs), and brecciated horizons with complex mixtures of vertical and horizontal components. We analyzed vertical and brecciated horizons to assess the timing and origin of fluid flow and its implications for diagenetic history of the Montney Fm. Aqueous and petroleum bearing fluid inclusions were observed in both vertical and brecciated zones; however, they did not occur in the same fluid inclusion assemblages. Petroleum inclusions occur as secondary fluid inclusions (e.g. in healed fractures and along cleavage planes) alongside primary aqueous inclusions indicating petroleum inclusions post-date aqueous inclusions and suggest multiple phases of fluid flow is recorded within these fractures. Raman spectroscopy of aqueous inclusions also display no evidence of petroleum compounds supporting the absence or low abundance of petroleum fluids during the formation of aqueous fluid inclusions. Pressure-corrected trapping temperatures (&gt;140°C) are likely associated with the period of maximum burial during the Laramide orogeny based on burial history modelling. Ice melt temperatures of aqueous fluid inclusions are consistent with 19% NaCl equiv. brine and eutectic temperatures (-51°C) indicate NaCl-CaCl2 composition. Combined use of aqueous and petroleum fluid inclusions in deeply buried sedimentary systems offers a promising tool for better understanding the diagenetic fluid history and helps constrain the pressure-temperature history important for characterizing economically important geologic formations.
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Shenker, Moshe, Paul R. Bloom, Abraham Shaviv, Adina Paytan, Barbara J. Cade-Menun, Yona Chen y Jorge Tarchitzky. Fate of Phosphorus Originated from Treated Wastewater and Biosolids in Soils: Speciation, Transport, and Accumulation. United States Department of Agriculture, junio de 2011. http://dx.doi.org/10.32747/2011.7697103.bard.
Texto completoResumen
Beneficial use of reclaimed wastewater (RW) and biosolids (BS) in soils is accompanied by large input of sewage-originated P. Prolonged application may result in P accumulation up to levelsBeneficial use of reclaimed wastewater (RW) and biosolids (BS) in soils is accompanied by large input of sewage-originated P. Prolonged application may result in P accumulation up to levels that impair plant nutrition, increase P loss, and promote eutrophication in downstream waters. This study aims to shed light on the RW- and BS-P forms in soils and to follow the processes that determine P reactivity, solubility, availability, and loss in RW and BS treated soils. The Technion group used sequential P extraction combined with measuring stable oxygen isotopic composition in phosphate (δ18OP) and with 31P-NMR studies to probe P speciation and transformations in soils irrigated with RW or fresh water (FW). The application of the δ18OP method to probe inorganic P (Pi) speciation and transformations in soils was developed through collaboration between the Technion and the UCSC groups. The method was used to trace Pi in water-, NaHCO3-, NaOH-, and HCl- P fractions in a calcareous clay soil (Acre, Israel) irrigated with RW or FW. The δ18OP signature changes during a month of incubation indicated biogeochemical processes. The water soluble Pi (WSPi) was affected by enzymatic activity yielding isotopic equilibrium with the water molecules in the soil solution. Further it interacted rapidly with the NaHCO3-Pi. The more stable Pi pools also exhibited isotopic alterations in the first two weeks after P application, likely related to microbial activity. Isotopic depletion which could result from organic P (PO) mineralization was followed by enrichment which may result from biologic discrimination in the uptake. Similar transformations were observed in both soils although transformations related to biological activity were more pronounced in the soil treated with RW. Specific P compounds were identified by the Technion group, using solution-state 31P-NMR in wastewater and in soil P extracts from Acre soils irrigated by RW and FW. Few identified PO compounds (e.g., D-glucose-6-phosphate) indicated coupled transformations of P and C in the wastewater. The RW soil retained higher P content, mainly in the labile fractions, but lower labile PO, than the FW soil; this and the fact that P species in the various soil extracts of the RW soil appear independent of P species in the RW are attributed to enhanced biological activity and P recycling in the RW soil. Consistent with that, both soils retained very similar P species in the soil pools. The HUJ group tested P stabilization to maximize the environmental safe application rates and the agronomic beneficial use of BS. Sequential P extraction indicated that the most reactive BS-P forms: WSP, membrane-P, and NaHCO3-P, were effectively stabilized by ferrous sulfate (FeSul), calcium oxide (CaO), or aluminum sulfate (alum). After applying the stabilized BS, or fresh BS (FBS), FBS compost (BSC), or P fertilizer (KH2PO4) to an alluvial soil, P availability was probed during 100 days of incubation. A plant-based bioassay indicated that P availability followed the order KH2PO4 >> alum-BS > BSC ≥ FBS > CaO-BS >> FeSul-BS. The WSPi concentration in soil increased following FBS or BSC application, and P mineralization further increased it during incubation. In contrast, the chemically stabilized BS reduced WSPi concentrations relative to the untreated soil. It was concluded that the chemically stabilized BS effectively controlled WSPi in the soil while still supplying P to support plant growth. Using the sequential extraction procedure the persistence of P availability in BS treated soils was shown to be of a long-term nature. 15 years after the last BS application to MN soils that were annually amended for 20 years by heavy rates of BS, about 25% of the added BS-P was found in the labile fractions. The UMN group further probed soil-P speciation in these soils by bulk and micro X-ray absorption near edge structure (XANES). This newly developed method was shown to be a powerful tool for P speciation in soils. In a control soil (no BS added), 54% of the total P was PO and it was mostly identified as phytic acid; 15% was identified as brushite and 26% as strengite. A corn crop BS amended soil included mostly P-Fe-peat complex, variscite and Al-P-peat complex but no Ca-P while in a BS-grass soil octacalcium phosphate was identified and o-phosphorylethanolamine or phytic acid was shown to dominate the PO fraction that impair plant nutrition, increase P loss, and promote eutrophication in downstream waters. This study aims to shed light on the RW- and BS-P forms in soils and to follow the processes that determine P reactivity, solubility, availability, and loss in RW and BS treated soils. The Technion group used sequential P extraction combined with measuring stable oxygen isotopic composition in phosphate (δ18OP) and with 31P-NMR studies to probe P speciation and transformations in soils irrigated with RW or fresh water (FW). The application of the δ18OP method to probe inorganic P (Pi) speciation and transformations in soils was developed through collaboration between the Technion and the UCSC groups. The method was used to trace Pi in water-, NaHCO3-, NaOH-, and HCl- P fractions in a calcareous clay soil (Acre, Israel) irrigated with RW or FW. The δ18OP signature changes during a month of incubation indicated biogeochemical processes. The water soluble Pi (WSPi) was affected by enzymatic activity yielding isotopic equilibrium with the water molecules in the soil solution. Further it interacted rapidly with the NaHCO3-Pi. The more stable Pi pools also exhibited isotopic alterations in the first two weeks after P application, likely related to microbial activity. Isotopic depletion which could result from organic P (PO) mineralization was followed by enrichment which may result from biologic discrimination in the uptake. Similar transformations were observed in both soils although transformations related to biological activity were more pronounced in the soil treated with RW. Specific P compounds were identified by the Technion group, using solution-state 31P-NMR in wastewater and in soil P extracts from Acre soils irrigated by RW and FW. Few identified PO compounds (e.g., D-glucose-6-phosphate) indicated coupled transformations of P and C in the wastewater. The RW soil retained higher P content, mainly in the labile fractions, but lower labile PO, than the FW soil; this and the fact that P species in the various soil extracts of the RW soil appear independent of P species in the RW are attributed to enhanced biological activity and P recycling in the RW soil. Consistent with that, both soils retained very similar P species in the soil pools. The HUJ group tested P stabilization to maximize the environmental safe application rates and the agronomic beneficial use of BS. Sequential P extraction indicated that the most reactive BS-P forms: WSP, membrane-P, and NaHCO3-P, were effectively stabilized by ferrous sulfate (FeSul), calcium oxide (CaO), or aluminum sulfate (alum). After applying the stabilized BS, or fresh BS (FBS), FBS compost (BSC), or P fertilizer (KH2PO4) to an alluvial soil, P availability was probed during 100 days of incubation. A plant-based bioassay indicated that P availability followed the order KH2PO4 >> alum-BS > BSC ≥ FBS > CaO-BS >> FeSul-BS. The WSPi concentration in soil increased following FBS or BSC application, and P mineralization further increased it during incubation. In contrast, the chemically stabilized BS reduced WSPi concentrations relative to the untreated soil. It was concluded that the chemically stabilized BS effectively controlled WSPi in the soil while still supplying P to support plant growth. Using the sequential extraction procedure the persistence of P availability in BS treated soils was shown to be of a long-term nature. 15 years after the last BS application to MN soils that were annually amended for 20 years by heavy rates of BS, about 25% of the added BS-P was found in the labile fractions. The UMN group further probed soil-P speciation in these soils by bulk and micro X-ray absorption near edge structure (XANES). This newly developed method was shown to be a powerful tool for P speciation in soils. In a control soil (no BS added), 54% of the total P was PO and it was mostly identified as phytic acid; 15% was identified as brushite and 26% as strengite. A corn crop BS amended soil included mostly P-Fe-peat complex, variscite and Al-P-peat complex but no Ca-P while in a BS-grass soil octacalcium phosphate was identified and o-phosphorylethanolamine or phytic acid was shown to dominate the PO fraction.