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Carbon-isotope record of the Early Jurassic (Toarcian) Oceanic Anoxic Event from fossil wood and marine carbonate (Lusitanian Basin, Portugal)

Hesselbo, Stephen P.; Jenkyns, Hugh C.; Duarte, Luis V.; Oliveira, Luiz C.V.
Fonte: Universidade de Coimbra Publicador: Universidade de Coimbra
Tipo: Artigo de Revista Científica Formato: aplication/PDF
ENG
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36.83%
The Toarcian Oceanic Anoxic Event (OAE) in the Early Jurassic (~ 183 Ma ago) was characterized by widespread near-synchronous deposition of organic-rich shales in marine settings, as well as perturbations to several isotopic systems. Characteristically, two positive carbon-isotope excursions in a range of materials are separated by an abrupt negative shift. Carbon-isotope profiles from Toarcian fossil wood collected in England and Denmark have previously been shown to exhibit this large drop (~ - 7[per mille sign]) in [delta]13C values, interpreted as due to an injection of isotopically light CO2 into the ocean-atmosphere system. However, the global nature of this excursion has been challenged on the basis of carbon-isotope data from nektonic marine molluscs (belemnites), which exhibit heavier than expected carbon-isotope values. Here we present new data, principally from fossil wood and bulk carbonate collected at centimetre scale from a hemipelagic section at Peniche, coastal Portugal. This section is low in organic carbon (average TOC = ~ 0.5%), and the samples should not have suffered significant diagenetic contamination by organic carbon of marine origin. The carbon-isotope profile based on wood shows two positive excursions separated by a large and abrupt negative excursion...

Sistemática isotópica de Os-Nd-Pb-Sr e geoquímica de elementos traço litófilos e siderófilos de basaltos da Província Magmática do Paraná; Os-Nd-Pb-Sr isotope systematics and lithophile and siderophile trace element geochemistry of basalts from Paraná Magmatic Province.

Rocha Júnior, Eduardo Reis Viana
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 06/01/2011 PT
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O objetivo primário deste estudo é aprimorar o conhecimento acerca das fontes do manto e dos mecanismos envolvidos na gênese dos basaltos da Província Magmática do Paraná, que constitui uma das maiores manifestações de basaltos continentais do mundo. Para tanto, foram determinadas as concentrações de terras raras (La, Ce, Nd, Sm, Eu, Tb, Yb e Lu), outros elementos traço (Cs, Rb, Ba, U, Th, Ta, Hf, Co e Sc) e elementos altamente siderófilos (Os, Ir, Ru, Pt, Pd e Re), juntamente com razões isotópicas dos sistemas Rb-Sr, Sm-Nd, U-Th-Pb e Re-Os em basaltos com alto-Ti (Paranapanema e Pitanga) que ocorrem no norte da PMP. Além disso, foram determinadas as concentrações de elementos altamente siderófilos e as razões isotópicas de 187Os/188Os amostras representativas de basaltos com baixo-Ti (Esmeralda) do sul da PMP. Os dados geoquímicos e as razões isotópicas de Sr, Nd e Pb obtidos são consistentes com dados da literatura, porém, refinam as variações (extremos) isotópicas dos magmas-tipo Paranapanema e Pitanga. Esses dados, juntamente com as concentrações de elementos altamente siderófilos e das razões isotópicas de Os, inéditas na literatura, sugerem que as fontes dos basaltos (astenosfera ou manto litosférico subcontinental) sofreram metassomatismo significativo...

Isotope analysis (delta C-13) of pulpy whole apple juice

Figueira, Ricardo; Venturini Filho, Waldemar Gastoni; Ducatti, Carlos; Parente Nogueira, Andressa Milene
Fonte: Soc Brasileira Ciência Tecnologia Alimentos Publicador: Soc Brasileira Ciência Tecnologia Alimentos
Tipo: Artigo de Revista Científica Formato: 660-665
ENG
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP); Processo FAPESP: 06/60898-7; The objectives of this study were to develop the method of isotope analysis to quantify the carbon of C-3 photosynthetic cycle in pulpy whole apple juice and to measure the legal limits based on Brazilian legislation in order to identify the beverages that do not conform to the Ministry of Agriculture, Livestock and Food Supply (MAPA). This beverage was produced in a laboratory according to the Brazilian law. Pulpy juices adulterated by the addition of sugarcane were also produced. The isotope analyses measured the relative isotope enrichment of the juices, their pulpy fractions (internal standard) and purified sugar. From those results, the quantity of C-3 source was estimated by means of the isotope dilution equation. To determine the existence of adulteration in commercial juices, it was necessary to create a legal limit according to the Brazilian law. Three brands of commercial juices were analyzed. One was classified as adulterated. The legal limit enabled to clearly identify the juice that was not in conformity with the Brazilian law. The methodology developed proved efficient for quantifying the carbon of C-3 origin in commercial pulpy apple juices.

Isotope analysis (δ 13c) of pulpy whole apple juice

Figueira, Ricardo; Venturini Filho, Waldemar Gastoni; Ducatti, Carlos; Nogueira, Andressa Milene Parente
Fonte: Sociedade Brasileira de Ciência e Tecnologia de Alimentos Publicador: Sociedade Brasileira de Ciência e Tecnologia de Alimentos
Tipo: Artigo de Revista Científica Formato: 660-665
ENG
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP); Os objetivos deste trabalho foram desenvolver o método de análise isotópica para quantificar o carbono do ciclo fotossintético C3 em sucos com polpa de maçã integral e mensurar o limite de legalidade, baseado na legislação brasileira, para identificar as bebidas que não estão em conformidade com o Ministério da Agricultura, Pecuária e Abastecimento (MAPA). Esta bebida foi produzida em laboratório, conforme a legislação brasileira. Também foram produzidos sucos polposos adulterados com adição de açúcar de cana. Nas análises isotópicas foi mensurado o enriquecimento isotópico relativo dos sucos e de suas frações polpa (padrão interno) e açúcar purificado. Com estes resultados foi estimada a quantidade de fonte C3 pela equação da diluição isotópica. Para determinar a existência de adulteração nos sucos comerciais foi necessária a criação do limite de legalidade de acordo com a legislação brasileira. Três marcas de sucos comerciais foram analisadas. Uma foi classificada como adulterada. O limite de legalidade possibilitou identificar claramente o suco que estava em inconformidade com a legislação brasileira. A metodologia desenvolvida provou ser eficiente para quantificar o carbono de origem C3 em sucos polposos de maçã comerciais.; The objectives of this study were to develop the method of isotope analysis to quantify the carbon of C3 photosynthetic cycle in pulpy whole apple juice and to measure the legal limits based on Brazilian legislation in order to identify the beverages that do not conform to the Ministry of Agriculture...

Carbon isotope composition as a tool for quality control of herbs, spices and medicinal plants

Marchese, José Abramo; Ming, Lin Chau; Ducatti, Carlos; Tadeu Da Silva, Evandro
Fonte: Universidade Estadual Paulista Publicador: Universidade Estadual Paulista
Tipo: Conferência ou Objeto de Conferência Formato: 185-187
ENG
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Isotope screening is a simple and cheap test for determining the photosynthetic pathway used by plants. The scope of this work was to classify the photosynthetic type of Melissa officinalis L. and Cymbopogon citratus [DC.] Stapf, through studies of the carbon isotope composition (δ13 C), and we are proposing the use of carbon isotope composition results as a tool to control the quality of medicinal plants. For studies of δ 13C (13 C% = [R (sample)/R (standard) - 1] × 10 -3), dried, powdered leaves were analyzed in a mass spectrometer coupled with an elemental analyzer for determining the ratio R (R = 13CO2/12CO2). As results, M. officinalis presented a C3 photosynthetic type, and C. citratus presented a C4 photosynthetic type. The carbon isotope composition from this study can be used as quality control of M. officinalis adulterants.

Uranium-lead dating method at the Pará-Iso isotope geology laboratory, UFPA, Belém - Brazil

Krymsky,Robert S.; Macambira,Moacir J.B.; Lafon,Jean-Michel; Estumano,Gérson S.
Fonte: Academia Brasileira de Ciências Publicador: Academia Brasileira de Ciências
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/03/2007 EN
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Analytical procedures for U-Pb isotope dilution analyses at the Pará-Iso isotope geology laboratory of the Federal University of Pará (UFPA) are described in detail. The procedures are applied to zircon, titanite, rutile, apatite, columbite-tantalite and whole rock. Reagent preparation and chemical processing are done in clean-room conditions. Samples are dissolved using TeflonTM microcapsules in steel jacket TeflonTM Parr InstrumentTM bomb or TeflonTM screw cap containers. U and Pb are separated using anion exchange AG 1x8 resin columns. Typical blanks for mineral sample amounts of 0.01 to 1.0 mg are less than 1 pg U and 20-30 pg Pb. Isotope analysis of the U and Pb from the same filament are carried out using a Finnigan MAT 262 mass-spectrometer in static and dynamic modes. The current analytical level is demonstrated on analyses of international standard zircon 91500 with three different 235U-205Pb and 235U-208Pb isotope tracers and whole rock standards. Results of analyses of two zircon samples are also presented.

Modeling nuclear volume isotope effects in crystals

Schauble, Edwin A.
Fonte: National Academy of Sciences Publicador: National Academy of Sciences
Tipo: Artigo de Revista Científica
EN
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Mass-independent isotope fractionations driven by differences in volumes and shapes of nuclei (the field shift effect) are known in several elements and are likely to be found in more. All-electron relativistic electronic structure calculations can predict this effect but at present are computationally intensive and limited to modeling small gas phase molecules and clusters. Density functional theory, using the projector augmented wave method (DFT-PAW), has advantages in greater speed and compatibility with a three-dimensional periodic boundary condition while preserving information about the effects of chemistry on electron densities within nuclei. These electron density variations determine the volume component of the field shift effect. In this study, DFT-PAW calculations are calibrated against all-electron, relativistic Dirac–Hartree–Fock, and coupled-cluster with single, double (triple) excitation methods for estimating nuclear volume isotope effects. DFT-PAW calculations accurately reproduce changes in electron densities within nuclei in typical molecules, when PAW datasets constructed with finite nuclei are used. Nuclear volume contributions to vapor–crystal isotope fractionation are calculated for elemental cadmium and mercury...

Unexpected variations in the triple oxygen isotope composition of stratospheric carbon dioxide

Wiegel, Aaron A.; Cole, Amanda S.; Hoag, Katherine J.; Atlas, Elliot L.; Schauffler, Sue M.; Boering, Kristie A.
Fonte: National Academy of Sciences Publicador: National Academy of Sciences
Tipo: Artigo de Revista Científica
EN
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We report observations of stratospheric CO2 that reveal surprisingly large anomalous enrichments in 17O that vary systematically with latitude, altitude, and season. The triple isotope slopes reached 1.95 ± 0.05(1σ) in the middle stratosphere and 2.22 ± 0.07 in the Arctic vortex versus 1.71 ± 0.03 from previous observations and a remarkable factor of 4 larger than the mass-dependent value of 0.52. Kinetics modeling of laboratory measurements of photochemical ozone–CO2 isotope exchange demonstrates that non–mass-dependent isotope effects in ozone formation alone quantitatively account for the 17O anomaly in CO2 in the laboratory, resolving long-standing discrepancies between models and laboratory measurements. Model sensitivities to hypothetical mass-dependent isotope effects in reactions involving O3, O(1D), or CO2 and to an empirically derived temperature dependence of the anomalous kinetic isotope effects in ozone formation then provide a conceptual framework for understanding the differences in the isotopic composition and the triple isotope slopes between the laboratory and the stratosphere and between different regions of the stratosphere. This understanding in turn provides a firmer foundation for the diverse biogeochemical and paleoclimate applications of 17O anomalies in tropospheric CO2...

Vibronic origin of sulfur mass-independent isotope effect in photoexcitation of SO2 and the implications to the early earth’s atmosphere

Whitehill, Andrew R.; Xie, Changjian; Hu, Xixi; Xie, Daiqian; Guo, Hua; Ono, Shuhei
Fonte: National Academy of Sciences Publicador: National Academy of Sciences
Tipo: Artigo de Revista Científica
EN
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36.86%
Signatures of mass-independent isotope fractionation (MIF) are found in the oxygen (16O,17O,18O) and sulfur (32S, 33S, 34S, 36S) isotope systems and serve as important tracers of past and present atmospheric processes. These unique isotope signatures signify the breakdown of the traditional theory of isotope fractionation, but the physical chemistry of these isotope effects remains poorly understood. We report the production of large sulfur isotope MIF, with Δ33S up to 78‰ and Δ36S up to 110‰, from the broadband excitation of SO2 in the 250–350-nm absorption region. Acetylene is used to selectively trap the triplet-state SO2 (3B1), which results from intersystem crossing from the excited singlet (1A2/1B1) states. The observed MIF signature differs considerably from that predicted by isotopologue-specific absorption cross-sections of SO2 and is insensitive to the wavelength region of excitation (above or below 300 nm), suggesting that the MIF originates not from the initial excitation of SO2 to the singlet states but from an isotope selective spin–orbit interaction between the singlet (1A2/1B1) and triplet (3B1) manifolds. Calculations based on high-level potential energy surfaces of the multiple excited states show a considerable lifetime anomaly for 33SO2 and 36SO2 for the low vibrational levels of the 1A2 state. These results demonstrate that the isotope selectivity of accidental near-resonance interactions between states is of critical importance in understanding the origin of MIF in photochemical systems.

On the mechanisms of sulfur isotope fractionation during microbial sulfate reduction

Leavitt, William Davie
Fonte: Harvard University Publicador: Harvard University
Tipo: Thesis or Dissertation
EN_US
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Underlying all applications of sulfur isotope analyses is our understanding of isotope systematics. This dissertation tests some fundamental assumptions and assertions, drawn from equilibrium theory and a diverse body of empirical work on biochemical kinetics, as applied to the multiple sulfur isotope systematics of microbial sulfate reduction. I take a reductionist approach, both in the questions addressed and experimental approaches employed. This allows for a mechanistic, physically consistent interpretation of geological and biological sulfur isotope records. The goal of my work here is to allow interpreters a more biologically, chemically and physically parsimonious framework to decipher the signals coded in modern and ancient sulfur isotope records.; Earth and Planetary Sciences

Measurement of labile Cu in soil using stable isotope dilution and isotope ratio analysis by ICP-MS

Nolan, A.; Ma, Y.; Lombi, E.; McLaughlin, M.
Fonte: Springer-Verlag Publicador: Springer-Verlag
Tipo: Artigo de Revista Científica
Publicado em //2004 EN
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Isotope dilution is a useful technique to measure the labile metal pool, which is the amount of metal in soil in rapid equilibrium (<7 days) with the soil solution. This is normally performed by equilibrating soil with a metal isotope, and sampling the labile metal pool by using an extraction (E value), or by growing plants (L value). For Cu, this procedure is problematic for E values, and impossible for L values, due to the short half-life of the 64Cu radioisotope (12.4 h), which makes access and handling very difficult. We therefore developed a technique using enriched 65Cu stable isotope and measurement of 63Cu/65Cu ratios by quadrupole inductively coupled plasma mass spectrometry (ICP-MS) to measure labile pools of Cu in soils using E value techniques. Mass spectral interferences in detection of 63Cu/65Cu ratios in soil extracts were found to be minimal. Isotope ratios determined by quadrupole ICP-MS compared well to those determined by high-resolution (magnetic sector) ICP-MS. E values determined using the stable isotope technique compared well to those determined using the radioisotope for both uncontaminated and Cu-contaminated soils.; Annette L. Nolan, Yibing Ma, Enzo Lombi and Mike J. McLaughlin

Principles of stable isotope fractionation during anaerobic respiration; Prinzipien der stabilen Isotopenfraktionierung während anaerober Atmungsprozesse

Mangalo, Muna
Fonte: Universidade de Tubinga Publicador: Universidade de Tubinga
Tipo: Dissertação
EN
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The measurements of stable isotope ratios in sulfate and nitrate have proven to be extremely useful for identification and quantification of microbial processes in the environment. Bacterial sulfate reduction as well as denitrification is accompanied by a fractionation of the stable isotopes of the respective electron acceptor leading to an enrichment of the heavier isotope in the remaining fraction. The main objective of this study was to contribute to the fundamental understanding of anaerobic reduction processes and the related isotope effects in the residual sulfate and nitrate. Therefore, experiments on sulfate reduction and denitrification were performed with pure cultures. The dual isotope approach (O, S/N) was used to elucidate the influences on the oxygen isotope fractionation, as well as to explain the high variability of sulfur and nitrogen isotope enrichment during the respective respiration processes. Hence, the findings of this study on a microscale help to understand and to quantify these processes on a macroscale. The present thesis includes three chapters and the intention, the used approach and the results of each chapter is briefly summarized below: CHAPTER 1: STABLE ISOTOPE FRACTIONATION DURING BACTERIAL SULFATE REDUCTION IS CONTROLLED BY REOXIDATION OF INTERMEDIATES Basic principles in stable isotope fractionation of sulfur and a suggested oxygen isotope exchange between residual sulfate and water during bacterial sulfate reduction were investigated by a systematic study. Batch experiments with four sulfate-reducing strains (Desulfovibrio desulfuricans...

Assessment of in situ transformation of Hexachlorocyclohexane using carbon stable isotope analysis (CSIA); Bewertung der in-situ-Transformation von Hexachlorcyclohexan mit Analyse die Carbon stabilen Isotope

Bashir, Safdar
Fonte: Universidade de Tubinga Publicador: Universidade de Tubinga
Tipo: Dissertação
EN
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36.93%
The European environment agency listed around 250,000 contaminated field sites which need to be cleaned due to the hazardous effects they pose on human and ecosystem health. This number is expected to increase over the next years. Similar is the case of hexachlorocyclohexane (HCH) contamination and it is estimated that four to six million tons of various HCH materials have been dumped worldwide, which need an urgent removal from the environment. HCH can undergo degradation by microorganisms indigenous to the soil or groundwater. Therefore natural attenuation (NA), relying on the in situ biodegradation of pollutants is considered as a cost effective remediation strategy. However, it requires accurate monitoring techniques. Carbon stable isotope analysis (CSIA) is a powerful technique to provide information on the extent of degradation. α-HCH as many other organic components appear as a racemic mixture of enantiomers in the environment and enantiomer fraction (EF) can provide information on biodegradation. The combination of enantiomeric fraction (EF), CSIA and the enantiomer selective stable isotope analysis (ESIA) has potential for distinguishing transformation processes of contaminants in situ. To validate the applicability of CSIA for HCH...

New method for separation of magnetite from rock samples for oxygen isotope analysis

Jim??nez-L??pez, Concepci??n; Rodr??guez-Navarro, Alejandro; P??rez-Gonz??lez, Teresa; Carrillo-Ros??a, Javier; Boyce, Adrian J.; Romanek, Christopher S.
Fonte: E. Schweizerbart Science Publishers Publicador: E. Schweizerbart Science Publishers
Tipo: Pré-impressão
ENG
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Este art??culo ha sido publicado en la Revista European Journal of Mineralogy, correspondiendo la presente versi??n a un preprint; A new procedure is described to separate magnetite from milligram sized samples of crushed rock for oxygen isotope analysis. This method is based on magnetic separation of magnetite after heating the mixture to a temperature that exceeds the Curie point for other magnetic minerals in a sample. The relatively low temperature of this procedure (350?? C) does not induce any reaction between magnetic mineral nor does it alter the isotope composition of magnetite. This procedure was tested on samples containing known percentages of magnetite and pyrrhotite. The percentage of magnetite in a sample was increased by 10-20 % through successive enrichment cycles until a pure magnetite separate was achieved. The separation should be performed before measuring the oxygen isotope composition of the magnetic fraction of a rock sample by laser ablation, because the presence of contaminating phases such as pyrrhotite may cause unwanted isotope partitioning of the oxygen released during fluorination. Our data show that contamination of a magnetite sample, even with a non O-bearing phase, can lead to systematically misleading O isotope data in a standard total laser fluorination system. Enrichment of the apparent magnetite value is indicated...

On the 16 O/ 18 O isotope effect associated with photosynthetic O 2 production

Tcherkez, Guillaume; Farquhar, Graham
Fonte: CSIRO Publishing Publicador: CSIRO Publishing
Tipo: Artigo de Revista Científica
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While photosynthetically evolved O2 has been repeatedly shown to have nearly the same oxygen isotope composition as source water so that there is no corresponding 16O/18O isotope effect, some recent 18O-enrichment studies suggest that a large isotope effe

Organic matter stable isotope (δ 13 C, δ 15 N) response to historical eutrophication of Lake Taihu, China

Wu, Jinglu; Lin, Lin; Gagan, Michael; Schleser, Gerhard; Wang, Sumin
Fonte: Kluwer Academic Publishers Publicador: Kluwer Academic Publishers
Tipo: Artigo de Revista Científica
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36.81%
We explored the use of carbon and nitrogen isotope ratios (δ13C, δ15N) in sediment organic matter as proxy indicators of historical changes in the trophic state of Lake Taihu, the third largest freshwater lake in China. Stable isotope signatures in four

Lead isotope ratio measurements by ICP-QMS to identify metal accumulation in vegetation specimens growing in mining environments

Marguí, Eva; Iglesias, M.; Queralt Mitjans, Ignacio; Hidalgo, M.
Fonte: Elsevier Publicador: Elsevier
Tipo: Artículo Formato: 206503 bytes; application/pdf
ENG
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The use of variations in stable Pb isotope ratios has become a well-established diagnostic technique for characterising sources of lead contamination. In this work, lead isotope ratios in mining wastes (lead content 320–130,000 mg kg− 1) and vegetation specimens (lead concentration 7–650 mg kg− 1) have been determined by inductively coupled plasma quadrupole-based mass spectrometry (ICP-QMS) in order to investigate lead bioaccumulation in Buddleia davidii growing on wastes from two abandoned Pb/Zn mining areas in Spain. The accuracy of the isotope ratio measurements was evaluated by analysing a certified isotopic standard NIST SRM 981. Good agreements were obtained between the lead isotope ratios measured and the certified values (deviations within 0.01–0.2%). The results indicate that the lead isotopic ratios in vegetation samples collected in the mining areas differed from those of a specimen from an uncontaminated site (control sample). However, close lead isotope ratio values were found between vegetation specimens and mining tailings. Therefore, the results suggest that lead in the collected vegetation specimens is most likely related to the influence of mining activities rather than to other sources like past leaded-petrol emissions.; This study was financed by the Spanish National Research Programme (CGL2004-05963-C04-03/HID). E. Marguí gratefully acknowledges a grant from the Autonomous Government of Catalonia (Ref.2002FI 00577).; Peer reviewed

Lead isotope ratios in Spanish coals of different characteristics and origin

Díaz Somoano, Mercedes; Suárez Ruiz, Isabel; Alonso, J. I. G.; Ruiz Encinar, J.; López Antón, María Antonia; Martínez Tarazona, María Rosa
Fonte: Elsevier Publicador: Elsevier
Tipo: Artículo Formato: 22195 bytes; application/pdf
ENG
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9 pages, 5 figures, 2 tables.-- Issue title: TSOP 2005 - Papers from the 22nd Annual Meeting of TSOP (Louisville, Kentucky, USA, Sep 11-15, 2005).; Lead isotope ratios in coals of different rank from several Spanish basins were estimated and related with their characteristics. The isotope Pb-206/Pb-207 ratio values of the coals studied range between 1.13 and 1.21, with the exception of some coal samples from the Cretaceous which are more radiogenic. Coals were classified into groups according to their lead isotope ratios. These in turn were related to the isotope ratios of the minerals galena, pyrite, chalcopyrite, and carbonates. Some of the low-rank coals, in which lead might be expected to be associated with the organic matter, were not found to be related with the isotope ratios of minerals. The isotope ratios of the individual densimetric fractions separated from a bituminous coal are different to those of the raw coal. The differences between these isotope ratios may not only be due to the diverse origin of lead in different coals, but also with the possible presence of several lead species incorporated from various sources in a particular coal. The results of this work represent an important contribution to the lead isotope ratio database essential for the accurate interpretation of data regarding pollution sources.; Peer reviewed

The effect of water status and soil fertility on the C-isotope signature in Pinus radiata

Korol, R L; Kirschbaum, Miko U. F.; Farquhar, Graham; Jeffreys, M
Fonte: Heron Publishing Publicador: Heron Publishing
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
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The efficiency with which trees use water is a major determinant of growth under water-limited conditions. We investigated whether increased access to water and nutrients alters water-use efficiency in Pinus radiata D. Don. Intrinsic transpiration efficiency, defined here as the ratio of CO2 assimilated and water transpired at a given vapor pressure deficit, is determined by the difference between ambient atmospheric CO2 concentration (C(a)) and leaf intercellular CO2 concentration (C(i)). The mean value of c(i)/c(a) can be inferred from an analysis of carbon isotope discrimination (Δ) in wood samples. A total of 117 trees, growing at sites with widely varying soil and climatic conditions in Australia and New Zealand, were cored and distinct annual rings were analyzed for their carbon isotope ratio, and correlated with rainfall during the July-June growing season in the year in which the wood was grown. Where possible, carbon isotope ratios were compared for different years within the same trees. The c(i)/c(a) ratio decreased with decreasing water availability, suggesting that intrinsic transpiration efficiency increased with decreasing water availability. An increase in growing season rainfall of 900 mm resulted in an increase in Δ of about 2.0‰...

The determination of 11B/10B and 87Sr/86Sr isotope ratios by quadrupole-based ICP-MS for the fingerprinting of South African wine

Vorster,C.; Greeff,L.; Coetzee,P.P.
Fonte: South African Journal of Chemistry Publicador: South African Journal of Chemistry
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/01/2010 EN
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The 11B/10B and 87Sr/86Sr isotope ratios in wines and soils of four major South African wine-producing regions have been determined by quadrupole-based ICP-MS in order to establish a fingerprint for origin verification of the wines. The 11B/10B isotope ratio was found to be a useful tool to distinguish among the wines of the selected wine regions. In addition, the use of B isotope ratios together with elemental concentrations of selected indicator elements as independent variables in a linear discriminant analysis procedure was shown to be a highly successful method to classify wine according to geographical origin. A good correlation between the B and Sr isotope ratios in wine and its provenance soil was found. Both wine and soil samples were prepared using microwave-assisted digestion followed by the isolation of boron and strontium from the sample matrix through element-specific ion exchange. Isotope ratio measurements with good precision, ~0.1 % RSD, for both boron and strontium have been obtained. The 87Sr/86Sr ratio showed limited potential as an indicator of provenance in the wine-producing regions included in this study, since the wines of only one region could be distinguished from the others.