首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 15 毫秒
1.
We present a method that can differentiate between the varieties of grapes and the vintages of wines and show the relationship between the grapes, the wine and the geographic location. The place of origin and its geographic and climatic characteristics were determined by the isotopic ratios, 13C/12C of the ethanol and 18O/16O of the water content of wine (wine water), for southern Brazil wines. The producing subregions of Pinto Bandeira, Vale dos Vinhedos and Nova Pádua showed differences in the temperature, rainfall and humidity conditions used for the production under microvinification conditions of Merlot and Cabernet Sauvignon varieties, in the harvests of 2005 and 2006. An isotope ratio mass spectrometer coupled to an elemental analyzer was used to measure the 13C/12C of ethanol and the 18O/16O of wine water. Regardless of the grape variety used, it was possible to determine the subregion through measurement of the δ18O values in both harvests. The altitudes of the different subregions led to statistical differences and demonstrated an influence mainly on the δ18O values of wine water. The δ18O value of wine water was determined to be more selective for the determination of the cultivation subregions than the δ13C value of the ethanol. The altitude and latitude influenced mainly the δ 18O values of wine water and the ethanol. The climatic influences are more noteworthy in distinguishing the year of the harvest than the cultivation subregion. Copyright © 2010 John Wiley & Sons, Ltd.  相似文献   

2.

Isotopes of hydrogen (3H, 2H) and oxygen (18O) are perfect candidates for groundwater tracers. A survey of isotopic composition of 34 groundwater samples and one Lake from Vojvodina region (Serbia) is presented here. Tritium activity concentration and stable isotope composition (δ2H, δ18O), as well as deuterium excess, were determined. The groundwater samples lie on the groundwater regression line. Minor deviations and a few lower deuterium excess values indicate waters recharged in a different climate regime and subjected to evaporation, respectively. According to the obtained results, most of the analyzed groundwater can be characterized as modern waters, recharged mostly from precipitation.

  相似文献   

3.
An international collaborative study of isotopic methods applied to control the authenticity of vinegar was organized in order to support the recognition of these procedures as official methods. The determination of the 2H/1H ratio of the methyl site of acetic acid by SNIF-NMR (site-specific natural isotopic fractionation-nuclear magnetic resonance) and the determination of the 13C/12C ratio, by IRMS (isotope ratio mass spectrometry) provide complementary information to characterize the botanical origin of acetic acid and to detect adulterations of vinegar using synthetic acetic acid. Both methods use the same initial steps to recover pure acetic acid from vinegar. In the case of wine vinegar, the determination of the 18O/16O ratio of water by IRMS allows to differentiate wine vinegar from vinegars made from dried grapes. The same set of vinegar samples was used to validate these three determinations.The precision parameters of the method for measuring δ13C (carbon isotopic deviation) were found to be similar to the values previously obtained for similar methods applied to wine ethanol or sugars extracted from fruit juices: the average repeatability (r) was 0.45 ‰, and the average reproducibility (R) was 0.91‰. As expected from previous in-house study of the uncertainties, the precision parameters of the method for measuring the 2H/1H ratio of the methyl site were found to be slightly higher than the values previously obtained for similar methods applied to wine ethanol or fermentation ethanol in fruit juices: the average repeatability was 1.34 ppm, and the average reproducibility was 1.62 ppm. This precision is still significantly smaller than the differences between various acetic acid sources (δ13C and δ18O) and allows a satisfactory discrimination of vinegar types. The precision parameters of the method for measuring δ18O were found to be similar to the values previously obtained for other methods applied to wine and fruit juices: the average repeatability was 0.15‰, and the average reproducibility was 0.59‰. The above values are proposed as repeatability and reproducibility limits in the current state of the art.On the basis of this satisfactory inter-laboratory precision and on the accuracy demonstrated by a spiking experiment, the authors recommend the adoption of the three isotopic determinations included in this study as official methods for controlling the authenticity of vinegar.  相似文献   

4.
《Analytical letters》2012,45(18):2856-2864
This paper highlights the results of a study regarding the impact of geo-climatic conditions, the influence of grape varieties, and harvest year on the isotopic characterization of a wine from a specific vineyard area, using stable isotope ratio analysis by continuous flow mass spectrometry CF-IRMS. This analytical technique has made a significant contribution on wine characterization, by proving the botanical and geographical origin of the wine raw material.

A great variability was observed to sap 18O and 2H isotopic ratios for different types of vine (Vitis vinifera plant) from the studied area, Dealu Mare-Valea Calugareasca, reflecting the significant influence of variety on isotopic features. On the other hand, the comparison of stable isotopic fingerprints for rainfall water and sap revealed a close approximation value for 18O isotopic ratio, and an insignificant variation coefficient of 13C isotopic ratio in wine varieties (about 2.85%).

The results of isotopic characterization for grape vine sap and original wines for different varieties existing in Dealu Mare-Valea Calugareasca vineyard indicates the relevance of meteorological and viticulture parameters like precipitation, date of vintage, and grape cultivar for wine authentication process.  相似文献   

5.
δ18O analyses of water in the blood of domestic and wild pigs indicated that large isotopic differences exist between domestic and wild specimens of the same species (Sus scrofa) living in the same area. Similar isotopic differences are found between the δ18O(PO43–) values of bones from the two groups of animals. When δ18O values obtained from recent wild boar bones are introduced in the equation of the isotopic scale determined for domestic pigs, totally unreliable δ18O values of local meteoric water are obtained. The δ18O(PO43–) values measured in three groups of modern wild boar specimens allow the calculation of a first approximate equation which is quite different from that of domestic pigs. This isotopic scale should be accurately re‐calibrated for wild animals. Copyright © 2011 John Wiley & Sons, Ltd.  相似文献   

6.
He  Xuexian  Liu  Dunyi  Peng  Zicheng  Liu  Weiguo 《中国科学:化学(英文版)》2002,45(1):130-136

Stable oxygen isotopic compositions of a coral colony ofPorites lutea obtained on a core allowed the reconstruction of a 56-a (1943–1998) proxy record of the sea surface temperatures. This coral δ18O data are from the east of Hainan Island water (22°20’N, 110°39’E), South China Sea. The relationship between δ18O in the skeletal aragonite carbonate and the sea surface temperature (SST) is SST = -5.36 δ18OPDB-3.51 (r = 0.73,n = 470), dδ18O/d(SST) = -0.187‱/ °C; and the thermometer was set at monthly resolution. The 56-a (1943–1998) proxy record of the sea surface temperatures reflected the same change trend in the northern part of South China Sea as the air temperature change trend in China.

  相似文献   

7.
Stable isotope compositions of ancient halite fluid inclusions have been recognized to be valuable tools for reconstructing past environments. Nevertheless, in order to better understand the genesis of halite deposits, it could be of great interest to combine both δ2H and δ18O measurements of the water trapped as inclusions in the defects of the mineral lattice. We developed a method combining off‐axis integrated cavity output spectroscopy (OA‐ICOS) connected on line with a modified elemental analyzer (EA‐OA‐ICOS) to perform those measurements. The first step was to test the method with synthetic halite crystals precipitated in the laboratory from isotopically calibrated waters. Water isotopic signatures have been measured with conventional techniques, equilibration for δ18O and chromium reduction for δ2H. Then, we modified and optimized a conventional EA to connect it online with an OA‐ICOS instrument for H2O measurements. The technique is first evaluated for calibrated free water samples. The technique is also evaluated for salt matrix effect, accuracy, and linearity for both isotopic signatures. Then, the technique is used to measure simultaneously δ2H and δ18O values of halite water inclusions precipitated from the evaporation experiments. Data generated with this new technique appeared to be comparable with those inferred from prior off‐line technique studies. The advantages offered by the OA‐ICOS technique are the simultaneous acquisition of both isotopic ratios and the substantial reduction of data acquisition time and sample aliquot size. Natural halite samples have been analyzed with this method. Natural halite samples as old as Precambrian have also been analyzed with this method.  相似文献   

8.
Stable oxygen isotopic compositions of a coral colony ofPorites lutea obtained on a core allowed the reconstruction of a 56-a (1943–1998) proxy record of the sea surface temperatures. This coral δ18O data are from the east of Hainan Island water (22°20’N, 110°39’E), South China Sea. The relationship between δ18O in the skeletal aragonite carbonate and the sea surface temperature (SST) is SST = -5.36 δ18OPDB-3.51 (r = 0.73,n = 470), dδ18O/d(SST) = -0.187?/ °C; and the thermometer was set at monthly resolution. The 56-a (1943–1998) proxy record of the sea surface temperatures reflected the same change trend in the northern part of South China Sea as the air temperature change trend in China.  相似文献   

9.
A novel sampling device suitable for continuous, unattended field monitoring of rapid isotopic changes in environmental waters is described. The device utilises diffusion through porous PTFE tubing to deliver water vapour continuously from a liquid water source for analysis of δ18O and δD values by Cavity Ring‐Down Spectrometry (CRDS). Separation of the analysed water vapour from non‐volatile dissolved and particulate contaminants in the liquid sample minimises spectral interferences associated with CRDS analyses of many aqueous samples. Comparison of isotopic data for a range of water samples analysed by Diffusion Sampling‐CRDS (DS‐CRDS) and Isotope Ratio Mass Spectrometry (IRMS) shows significant linear correlations between the two methods allowing for accurate standardisation of DS‐CRDS data. The internal precision for an integration period of 3 min (standard deviation (SD) = 0.1 ‰ and 0.3 ‰ for δ18O and δD values, respectively) is similar to analysis of water by CRDS using an autosampler to inject and evaporate discrete water samples. The isotopic effects of variable air temperature, water vapour concentration, water pumping rate and dissolved organic content were found to be either negligible or correctable by analysis of water standards. The DS‐CRDS system was used to analyse the O and H isotope composition in short‐lived rain events. Other applications where finely time resolved water isotope data may be of benefit include recharge/discharge in groundwater/river systems and infiltration‐related changes in cave drip water. Copyright © 2011 John Wiley & Sons, Ltd.  相似文献   

10.
The purpose of this study was to investigate the possibility of identifying oil source areas by means of simple measurements on the natural samples avoiding time‐consuming sample treatments. The oxygen and carbon isotopic values of 150 samples of extra‐virgin olive oil from eight different Italian regions and from three different years of production were measured according to well‐established techniques. Statistical treatments of the results obtained show a very good correlation of the δ18O of oil with latitude, mean annual temperature, and mean relative humidity at the collection site. No correlation is found with elevation and mean annual precipitation. The shift of the oil δ18O per degree centigrade of the mean annual temperature is quantitatively close to that calculated for atmospheric precipitation in continental areas. Accordingly, in our measurements, the year of oil production can be identified on the basis of the δ18O value (mean 2004 temperatures were higher than 2005 temperatures). On the contrary, the oil δ13C values show no correlation with the above variables but only with latitude and, consequently, are less suitable for discriminating the geographic origin of oil. However, the δ13C values are suitable to indicate biological differentiation while the δ18O values are not. Copyright © 2009 John Wiley & Sons, Ltd.  相似文献   

11.
Recently available isotope ratio infrared spectroscopy can directly measure the isotopic composition of atmospheric water vapour (δ18O, δ2H), overcoming one of the main limitations of isotope ratio mass spectrometry (IRMS) methods. Calibrating these gas‐phase instruments requires the vapourisation of liquid standards since primary standards in principle are liquids. Here we test the viability of calibrating a wavelength‐scanned cavity ring‐down spectroscopy (CRDS) instrument with vapourised liquid standards. We also quantify the dependency of the measured isotope values on the water concentration for a range of isotopic compositions. In both liquid and vapour samples, we found an increase in δ18O and δ2H with water vapour concentration. For δ18O, the slope of this increase was similar for liquid and vapour, with a slight positive relationship with sample δ‐value. For δ2H, we found diverging patterns for liquid and vapour samples, with no dependence on δ‐value for vapour, but a decreasing slope for liquid samples. We also quantified tubing memory effects to step changes in isotopic composition, avoiding concurrent changes in the water vapour concentration. Dekabon tubing exhibited much stronger, concentration‐dependent, memory effects for δ2H than stainless steel or perfluoroalkoxy (PFA) tubing. Direct vapour measurements with CRDS in a controlled experimental chamber agreed well with results obtained from vapour simultaneously collected in cold traps analysed by CRDS and IRMS. We conclude that vapour measurements can be calibrated reliably with liquid standards. We demonstrate how to take the concentration dependencies of the δ‐values into account. Copyright © 2010 John Wiley & Sons, Ltd.  相似文献   

12.
The Nuclear and Technological Institute (Instituto Tecnológico e Nuclear—ITN) in cooperation with the International Atomic Energy Agency (IAEA) has been conducting a nationwide survey of hydrogen (2H/1H) and oxygen (18O/16O) isotopic composition of monthly precipitation since 1988. This paper focuses on basic features of spatial and temporal distribution of δ18O and δ2H in the precipitation over Continental Portugal derived from ITN database. Phenomenological relationships between stable isotopes composition of precipitation and various climate-related parameters (local air temperature, distance to the Atlantic coast, altitude, amount of precipitation) are established and discussed.  相似文献   

13.
Tree‐ring carbon and oxygen isotope ratios from live and recently dead trees may reveal important mechanisms of tree mortality. However, wood decay in dead trees may alter the δ13C and δ18O values of whole wood obscuring the isotopic signal associated with factors leading up to and including physiological death. We examined whole sapwood and α‐cellulose from live and dead specimens of ponderosa pine (Pinus ponderosa), one‐seed juniper (Juniperous monosperma), piñon pine (Pinus edulis) and white fir (Abies concolor), including those with fungal growth and beetle frass in the wood, to determine if α‐cellulose extraction is necessary for the accurate interpretation of isotopic compositions in the dead trees. We found that the offset between the δ13C or δ18O values of α‐cellulose and whole wood was the same for both live and dead trees across a large range of inter‐annual and regional climate differences. The method of α‐cellulose extraction, whether Leavitt‐Danzer or Standard Brendel modified for small samples, imparts significant differences in the δ13C (up to 0.4‰) and δ18O (up to 1.2‰) of α‐cellulose, as reported by other studies. There was no effect of beetle frass or blue‐stain fungus (Ophiostoma) on the δ13C and δ18O of whole wood or α‐cellulose. The relationships between whole wood and α‐cellulose δ13C for ponderosa, piñon and juniper yielded slopes of ~1, while the relationship between δ18O of whole wood and α‐cellulose was less clear. We conclude that there are few analytical or sampling obstacles to retrospective studies of isotopic patterns of tree mortality in forests of the western United States. Published in 2011 by John Wiley & Sons, Ltd.  相似文献   

14.
The effect of deuterium on the 13C and 15N chemical shifts of enaminones has been investigated. D/H isotope shifts are reported for neutral and protonated species, i.e., when the isotope is exchanged on the C(2)-, N-, or O-atoms. In cases of slow exchange the isotope shifts were obtained from solutions containing both isotopomers, whereas for fast exchange (acidic solutions) either separate NMR. sample tubes (15N-NMR.) or coaxial tubes (13C-NMR.) were used. In neutral molecules the isotope effects δC(D, H) are intrinsic in nature. In acidic solutions, the enaminocarbonyl cations formed exhibit δC(D, H)- and δN(D, H)-values which are discussed in terms of the proton transfer. The mesomeric character of the cations is reflected by characteristic features in the δC(D, H)- and δN(D, H)-values, which can be ascribed to isotopic perturbation of resonance. O-Protonation shifts in the 15N-resonance, observed for the first time, are large and positive (+60 to +76 ppm), in contrast to amides, where the effects are of the same sign but an order of magnitude smaller. Both protonation shifts and solvent-induced isotope effects are discussed in connection with the nucleophilic character of the reactive centers in the enaminone synthon.  相似文献   

15.
The reduction of silver phosphate with graphite under vacuum conditions was studied at final reaction temperatures varying from 430 to 915°C to determine: (i) the CO2 extraction yield, and (ii) the oxygen isotopic composition of CO2. The CO2 yield and oxygen isotopic composition were determined on a calibrated dual inlet and triple collector isotope ratio mass spectrometer. We observed the following three stages of the reduction process. (1) At temperatures below 590°C only CO2 is formed, while silver orthophosphate decays to pyrophosphate. (2) At higher temperatures, 590–830°C, predominantly CO is formed from silver pyrophosphate which decays to metaphosphate; this CO was always converted into CO2 by the glow discharge method. (3) At temperatures above 830°C the noticeable sublimation of silver orthophosphate occurs. This observation was accompanied by the oxygen isotope analysis of the obtained CO2. The measured δ18O value varied from ?11.93‰ (at the lowest temperature) to ?20.32‰ (at the highest temperature). The optimum reduction temperature range was found to be 780–830°C. In this temperature range the oxygen isotopic composition of CO2 is nearly constant and the reaction efficiency is relatively high. The determined difference between the δ18O value of oxygen in silver phosphate and that in CO2 extracted from this phosphate is +0.70‰. Copyright © 2010 John Wiley & Sons, Ltd.  相似文献   

16.
Carbonate oxygen (O) and carbon (C) isotopes are widely used as proxies for tracing the processes and physicochemical conditions of many geological events and environmental changes in Earth Science. In particular, O and C isotopic variations at micrometer scales revealed by modern microbeam analytical techniques such as SIMS and NanoSIMS are robust archives for reconstructing palaeoenvironment and paleoclimate changes at annual and seasonal resolution or even higher temporal resolution. Widespread application of carbonate O and C isotopic microanalysis in Earth Sciences, however, has been restricted due to limitation of high-quality carbonate reference materials for O and C isotopic microanalysis. We introduce in this paper a new calcite reference material for calcite O and C isotopic microanalysis. This calcite is collected from a drill-core of the Oka carbonatite complex (Quebec, Canada). We demonstrated that the Oka calcite is fairly homogeneous in O and C isotopic compositions at micrometer scales based on homogeneity test by hundreds of SIMS O and C isotopic analyses. Precise determinations by using conventional gas-source IRMS yield the recommended value of δ18OVPDB = −23.12 ± 0.15‰ (1SD) and δ13CVPDB = −5.23 ± 0.06‰ (1SD) for the Oka calcite, which has been certified as the first class of Chinese national certified reference material (GBW04481) for O and C isotopic microanalysis.  相似文献   

17.
Oxygen isotopes in animal tissues are directly related to body water composition and thus the environment. Accurate measurement of animal tissue δ18O provides information about local climate, an animal's geographical origin and subsequent movements, with wide applications in palaeobiology and forensic science. The genesis and evolution of tissue‐based oxygen isotopes within species and within individuals are complex. We present the first data, for non‐human primates, rhesus macaques (Macaca mulatta), on the relationship between oxygen isotope sources in bio‐apatite (PO4 and PCO3) and hair taken from six sample sites in Asia, ranging from western India to northern Vietnam. The range of values is similar within each tissue type, with good correlation between tissues (r = 0.791 to 0.908), allowing cross‐tissue extrapolations. This is important when the availability of suitable tissues is limited. Biological interpretation of the small data set is difficult: macaque diets are eclectic, and the samples are from various locations. However, factors such as overall climate, precipitation quantity and source, and altitude are clearly influencing the results for each discrete geographical grouping. Future work could be aimed at assessing δ18O tissue associations for other species as the relationships appear to be species‐specific. Copyright © 2011 John Wiley & Sons, Ltd.  相似文献   

18.
The present study was aimed to investigate the variation of stable isotopic ratios of carbon, nitrogen, hydrogen, and oxygen in wheat kernel along with different processed fractions from three geographical origins across 5 years using isotope ratio mass spectrometry (IRMS). Multiway ANOVA revealed significant differences among region, harvest year, processing, and their interactions for all isotopes. The region contributed the major variability in the δ13C ‰, δ2H ‰, δ15N ‰, and δ18O‰ values of wheat. Variation of δ13C ‰, δ15N ‰, and δ18O ‰ between wheat whole kernel and its products (break, reduction, noodles, and cooked noodles) were ?0.7‰, and no significant difference was observed, suggesting the reliability of these isotope fingerprints in geographical traceability of wheat‐processed fractions and foods. A significant influence of wheat processing was observed for δ2H values. By applying linear discriminant analysis (LDA) to the whole dataset, the generated model correctly classified over 91% of the samples according to the geographical origin. The application of these parameters will assist in the development of an analytical control procedure that can be utilized to control the mislabeling regarding geographical origin of wheat kernel and its products.  相似文献   

19.
We demonstrate an improved method based on continuous‐flow elemental analyser pyrolysis isotopic ratio mass spectrometry (CF‐EA‐PY‐IRMS) to measure the 2H/1H ratios of water trapped in halite crystals. Two challenges to overcome are the low hydrogen concentration of samples (10‐50 μmol H2·g?1) and the high chloride concentration released when reacting halite in an elemental analyser. We describe an optimization procedure for determining the 2H/1H ratio of this trapped water with an acceptable accuracy. This technique involves the use of a high‐temperature Cr reactor to quantitatively convert H2O into H2. The initial step was performed on halite crystals precipitated from a water reservoir where 2H/1H ratios were monitored from its initial stage until the end of evaporation. The 2H/1H isotopic analyses were automated online in continuous‐flow mode. Precision of the method was determined for those “synthetic” samples with hydrogen concentrations ranging from 0.2 to 0.5 wt%. 2H/1H isotopic ratios of evaporating waters bracket the compositions of water inclusions. The formation of fluid inclusions is not instantaneous and records the isotopic signature of the residual waters across a time range during which the isotopic values of the water still evolve. This property explains why the δ2HVSMOW standard deviation of ±5‰ (2σ) observed for 10‐mg aliquots of halite exceeds the instrumental error (about ±1.5‰ 2σ) determined on the basis of IAEA‐CH7, NBS 30, and NBS 22 references along with calibrated waters with and without added halite crystals. We also applied this method to Mesoproterozoic (1.4 Ga) and Neoproterozoic (0.8 Ga) halite samples with relatively low hydrogen concentrations (300‐1500 ppm). The measured δ2HVSMOW values for Precambrian waters range from ?89‰ to ?54‰. We propose that this technique offers a new perspective and great potential for palaeoenvironmental reconstructions based on the 2H/1H analyses of water trapped in halite.  相似文献   

20.
Distribution of 13C/12C isotopes in vegetative (roots, grapevine, leaves) and generative (berries) parts of vine plants of the West European genetically different varieties Cabernet Sauvignon and Aligoté growing on soils of Krasnodar krai and Rostov oblast, as well as autochthonous varieties Sibirkovy and Krasnostop Zolotovsky growing in Rostov oblast, has been studied using isotopic mass spectrometry methods. It has been shown that the variations of δ13C values in plant tissues and berries are related to the climatic conditions of plant growth: moisture (a sum of annual precipitation) and temperature (a sum of annual effective temperatures). The carbon isotope ratios of vegetative and generative parts of vine plants have been found to be noticeably affected by vine varieties. The different 13C contents in ethanol produced from wine of the Aligoté and Cabernet Sauvignon varieties grown in two Russian vineyard regions are due to vine growth conditions, variety attribution and wine production techniques. An analytically significant parameter determined as exemplified by the Aligoté and Cabernet Sauvignon varieties in fermentation of vine harvested in different seasons and in both vineyard regions was an increased 13C content in ethanol with respect to dry (non-volatile) residue in wine after distillation of ethanol. This characteristic has been determined by a systematic difference of about 1–2‰ between the δ13C value of ethanol and the dry residue. A relative constancy in the carbon isotope composition of ethanol and of the dry residue in the final product is the basis for determining the authenticity of grape wines by means of isotopic mass spectrometry irrespective of natural factors.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号