Search

Data extract of Master Thesis "Abflusskomponenten am Zastlerbach" by Simon Hoeg (1998) @ Institute of Hydrology, University of Freiburg, Germany

The monograph contains results of the coordinated research project conducted by the International Atomic Energy Agency with the purpose to explore the use of new isotope techniques together with conventional ones to better assess the hydrogeological conditions in the geological settings of nuclear power plant sites and to provide basic information that may be used for predicting the fate of radioactive contaminants, such as tritium, released into groundwater in case of a radiological accident and/or during normal operations. To this end, research projects were conducted in ten countries to characterize the groundwater system in the vicinity of NPPs which are at different stages of development. The monograph contains the reports of these ten research projects and a summary of the achievements of the individual projects. The results of the determination of isotopes 18O, 2H, 13C, 14C, 3H, 3Hе, 4Hе and noble gases in water were used. The results of traditional hydrochemical analyzes and distributions of 90Sr, uranium, and transuranic elements in groundwater were also used. This CRP aims to develop guidelines for studying the hydrogeological characteristics of groundwater in local and regional groundwater systems in the vicinity of nuclear power plants using environmental isotopes and conventional techniques. For scientists and engineers working in the field of hydrogeology, radioecology, and safety in nuclear energy, as well as for students and graduate students of geological and physical faculties of universities.

Made available in DSpace on 2021-06-25T11:57:10Z (GMT). No. of bitstreams: 0 Previous issue date: 2021-04-01 Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) Financiadora de Estudos e Projetos (FINEP) The use of stable isotopes of hydrogen and oxygen is a tool widely used to trace water paths along the hydrological cycle, providing support for understanding climatic conditions in different spatial scales. One of the main synoptic scale events acting in southeastern Brazil is the South Atlantic Convergence Zone (SACZ), which causes a large amount of precipitation from southern Amazonia to southeastern Brazil during the southern summer. In order to determine the isotopic composition of precipitation during the action of SACZ in Sao Francisco Xavier in southeastern Brazil, information from the Weather Forecasting and Climate Studies Center of the National Institute for Space Research (CPTEC) was used regarding SACZ performance days, the retrograde trajectories of the HYSPLIT model, and images from the GOES-16 satellite, in addition to the non-parametric statistical tests by Spearman and Kruskal-Wallis. A high frequency of air mass trajectories from the Amazon to southeastern Brazil was observed when the SACZ was operating. During the SACZ events, the average isotopic composition of precipitation was more depleted, with a delta O-18 of -9.9 parts per thousand (+/- 2.1 parts per thousand), a delta H-2 of -69.3 parts per thousand (+/- 17.9 parts per thousand), and d-excess of 10.1 parts per thousand (+/- 4.0 parts per thousand). When disregarding the SACZ performance, the annual isotopic composition can present an enrichment of 1.0 parts per thousand for delta O-18 and 8.8 parts per thousand for the delta H-2. The long-term monitoring of trends in the isotopic composition of precipitation during the SACZ events can assist in indicating the evapotranspiration contribution of the Amazon rainforest to the water supply of southeastern Brazil. Natl Inst Space Res INPE, BR-12227010 Sao Jose Dos Campos, Brazil Fed Univ Campina Grande UFCG, Acad Unit Atmospher Sci, BR-58428830 Campina Grande, Paraiba, Brazil Sao Paulo State Univ, Environm Studies Ctr, BR-13506900 Rio Claro, Brazil Sao Paulo State Univ, Environm Studies Ctr, BR-13506900 Rio Claro, Brazil CAPES: 2180/2017 FAPESP: 2018/16791-0 Financiadora de Estudos e Projetos (FINEP): 01.16.0076.00

Summary The doubly labeled water (DLW) method measures total energy expenditure (TEE) in free-living subjects. Several equations are used to convert isotopic data into TEE. Using the International Atomic Energy Agency (IAEA) DLW database (5,756 measurements of adults and children), we show considerable variability is introduced by different equations. The estimated rCO2 is sensitive to the dilution space ratio (DSR) of the two isotopes. Based on performance in validation studies, we propose a new equation based on a new estimate of the mean DSR. The DSR is lower at low body masses (, Graphical Abstract, Highlights 5,756 doubly labeled water (DLW) measures highlight variation from calculation equation We derive here new equations for calculating CO2 production when using DLW These equations outperform previous equations in validation studies We recommend these equations should be adopted in future studies using DLW in humans, Speakman et al. use a large database of doubly labeled water measurements to show the choice of equation for the calculation of energy expenditure introduces significant variation into the final estimate. They then derive new equations that outperform previous equations in validation studies against chamber calorimetry.

Water isotopes from plant xylem and surrounding environment are increasingly used in eco- hydrological studies. Carriere et al. [1] analyzed a dataset of water isotopes in (i) the xylem of three different tree species, (ii) the surrounding soil and drainage water and (iii) the underlying karst groundwater, to understand tree water uptake during drought in two different Mediterranean forests on karst setting. The xylem and soil water were extracted by cryogenic distillation. The full dataset was obtained with Isotope Ratio Mass Spectrometry (IRMS) and Isotope Ratio Infrared Spectrometer (IRIS), and included 219 measurements of d2H and d18O. Prompted by unexpected isotopic data characterized by a very negative deuterium excess, a subsample of 46 xylem samples and 9 soil water samples were double checked with both analytical techniques. IRMS and IRIS analyses yielded similar data. Therefore, the results reveal that laser spectrometry allows an accurate estimation of xylem and soil water isotopes. The dataset highlights a strong 2H depletion in xylem water for all species. Deuterium does not seem adequate to interpret ecological processes in this dataset given the strong fractionation.

Phytoplankton contribute half of the primary production in the biosphere and are the major source of energy for the Arctic Ocean ecosystem. While primary production measurements are therefore fundamental to our understanding of marine biogeochemical cycling, the extent to which current methods provide a definitive estimate of this process remains uncertain given differences in their underlying approaches and assumptions. This is especially the case in the Arctic Ocean, a region of the planet undergoing rapid evolution as a result of climate change, yet where primary production measurements are sparse. In this study, we compared three common methods for estimating primary production in the European Arctic Ocean: 1) production of 18O-labeled oxygen (GPP-18O), 2) changes in dissolved oxygen (GPP-DO) and 3) incorporation rates of 14C-labelled carbon into particulate organic carbon (14C-POC) and into total organic carbon (14C-TOC, the sum of dissolved and particulate organic carbon). Results show that primary production rates derived using oxygen methods showed good agreement across season and were strongly positively correlated. While also strongly correlated, higher scatter associated with seasonal changes was observed between 14C-POC and 14C-TOC. The 14C-TOC-derived rates were, on average, approximately 50 % of the oxygen-based estimates. However, the relationship between these estimates changed seasonally. In May, during a spring bloom of Phaeocystis sp., 14C-TOC was 52 % and 50 % of GPP-DO and GPP-18O respectively, while in August, during post-bloom conditions dominated by flagellates, 14C-TOC was 125 % of GPP-DO and 14C-TOC was 175 % of GPP-18O. Varying relationship between C and O rates may be the result of varying importance of respiration, where C-based rates estimate Net Primary Production (NPP) and O-based rates estimate Gross Primary Production (GPP).However, uncertainty remains in this comparison, given differing assumptions of the methods and the photosynthetic quotients.The median O:C ratio of 4.75 in May is within the range of that observed for other regions of the world's ocean. However, the median O:C ratio for August is < 1, lower than in any other reported region. Our results suggest further research is needed to estimate O:C in Arctic waters, and at different times of the seasonal cycle. © 2019 Sanz-Martín, Vernet, Cape, Cano, Delgado-Huertas, Reigstad, Wassmann and Duarte., This study is a contribution to the Carbon Bridge (RCN-226415) project funded by the Norwegian Research Council to MR. MS-M was supported by a predoctoral fellowship from the Fundación La Caixa and the unemployment benefit of Ministry of Labour, Migrations and Social Security, Spain. MV was partially funded by a fellowship from the Hanse-Wissenchaftskolleg, Delmenhorst, Germany and by a United States National Science Foundation award PLR-1443705. MC was partially funded by the NASA Headquarters under the NASA Earth and Space Science Fellowship Program – grant NNX12AN48H.

The site of Ulucak is pivotal in exploring the Neolithic of the eastern Aegean and western Anatolia. It has an impressive stratigraphic sequence stretching from the first half of the seventh millennium BC to the first half of the sixth millennium BC. Recent zooarchaeological analyses have provided insight into the importance of animal husbandry practices and dairying at the site throughout the Neolithic but also raised questions about the changing nature of herd management strategies and whether these differed for sheep and goat. The faunal data, coupled with the significance of the site and condition of the assemblage, prompted the application of a number of methodological techniques to assess differences between sheep and goat. In this paper, we combine traditional osteomorphological analysis, ancient DNA, collagen peptide mass fingerprinting (zooarchaeology by mass spectrometry, or ZooMS), and stable isotope analysis of δ18O and δ13C from tooth enamel carbonate as well as δ13C and δ15N from bone collagen. As such, this is the first study of its kind. We evaluate the juxtaposition of these four approaches and their application in this important case, with relevance for future studies in the region.

Understanding the hydrologic and hydrochemistry processes in the riparian area is of great importance for managing and protecting riparian water resources. This paper took a highly disturbed and polluted Shaying River Basin (SRB) of China as the study area. In this research, environmental tracers (hydrochemical and isotopic data of222Rn, &delta, 18O, and &delta, D) and corresponding models (two-component mixing model and 222Rn mass balance model) were employed to investigate the hydrologic and associated hydro-chemical process of riparian groundwater. The results indicated that rivers received groundwater discharge located at Xihua (J8), Zhoukou (Y1), Luohe (S2), and Shenqiu (SY2), and the mixing extent with groundwater was greater in wet seasons than in dry seasons. The 222Rn mass balance model showed that the flux of river water leakage was 3.27 &times, 10&minus, 4 m3/(s&middot, m) at the front of Zhoukou sluice while groundwater discharge was 3.50 &times, 3 m3/(s&middot, m) at the front of Shenqiu sluice during the sampling period. The cation exchange and the dissolution/precipitation of aquifer minerals (including calcite, dolomite, gypsum, and halite) were dominated by geochemical processes. The untreated sewage discharge and fertilizer usage were the main anthropogenic activities affecting the hydrochemistry process in surface water and riparian groundwater. Additionally, our results found that nitrate pollutants derived by riparian groundwater were potential threats to river quality at the lower reaches of Jialu River and Shenqiu county of Shaying River, where the nitrate inputs could be larger during the wet seasons because of higher groundwater discharge.

Increasing biodiversity has been linked to higher primary productivity in terrestrial ecosystems. However, the underlying ecophysiological mechanisms remain poorly understood. We investigated the effects of surrounding species richness (monoculture, two‐ and four‐species mixtures) on the ecophysiology of Lithocarpus glaber seedlings in experimental plots in subtropical China. A natural rain event isotopically labelled both the water uptaken by the L. glaber seedlings and the carbon in new photoassimilates through changes of photosynthetic discrimination. We followed the labelled carbon (C) and oxygen (O) in the plant–soil–atmosphere continuum. We measured gas‐exchange variables (C assimilation, transpiration and above‐ and belowground respiration) and δ13C in leaf biomass, phloem, soil microbial biomass, leaf‐ and soil‐respired CO 2 as well as δ18O in leaf and xylem water. The 13C signal in phloem and respired CO 2 in L. glaber in monoculture lagged behind those in species mixture, showing a slower transport of new photoassimilates to and through the phloem in monoculture. Furthermore, leaf‐water 18O enrichment above the xylem water in L. glaber increased after the rain in lower diversity plots suggesting a lower ability to compensate for increased transpiration. Lithocarpus glaber in monoculture showed higher C assimilation rate and water‐use efficiency. However, these increased C resources did not translate in higher growth of L. glaber in monoculture suggesting the existence of larger nongrowth‐related C sinks in monoculture. These ecophysiological responses of L. glaber, in agreement with current understanding of phloem transport are consistent with a stronger competition for water resources in monoculture than in species mixtures. Therefore, increasing species diversity in the close vicinity of the studied plants appears to alleviate physiological stress induced by water competition and to counterbalance the negative effects of interspecific competition on assimilation rates for L. glaber by allowing a higher fraction of the C assimilated to be allocated to growth in species mixture than in monoculture.

For more than two decades, research groups in hydrology, ecology, soil science, and biogeochemistry have performed cryogenic water extractions (CWEs) for the analysis of δ2H and δ18O of soil water. Recent studies have shown that extraction conditions (time, temperature, and vacuum) along with physicochemical soil properties may affect extracted soil water isotope composition. Here we present results from the first worldwide round robin laboratory intercomparison. We test the null hypothesis that, with identical soils, standards, extraction protocols, and isotope analyses, cryogenic extractions across all laboratories are identical. Two standard soils with different physicochemical characteristics along with deionized (DI) reference water of known isotopic composition were shipped to 16 participating laboratories. Participants oven-dried and rewetted the soils to 8 and 20 % gravimetric water content (WC), using the deionized reference water. One batch of soil samples was extracted via predefined extraction conditions (time, temperature, and vacuum) identical to all laboratories; the second batch was extracted via conditions considered routine in the respective laboratory. All extracted water samples were analyzed for δ18O and δ2H by the lead laboratory (Global Institute for Water Security, GIWS, Saskatoon, Canada) using both a laser and an isotope ratio mass spectrometer (OA-ICOS and IRMS, respectively). We rejected the null hypothesis. Our results showed large differences in retrieved isotopic signatures among participating laboratories linked to soil type and soil water content with mean differences compared to the reference water ranging from +18.1 to −108.4 ‰ for δ2H and +11.8 to −14.9 ‰ for δ18O across all laboratories. In addition, differences were observed between OA-ICOS and IRMS isotope data. These were related to spectral interferences during OA-ICOS analysis that are especially problematic for the clayey loam soils used. While the types of cryogenic extraction lab construction varied from manifold systems to single chambers, no clear trends between system construction, applied extraction conditions, and extraction results were found. Rather, observed differences in the isotope data were influenced by interactions between multiple factors (soil type and properties, soil water content, system setup, extraction efficiency, extraction system leaks, and each lab's internal accuracy). Our results question the usefulness of cryogenic extraction as a standard for water extraction since results are not comparable across laboratories. This suggests that defining any sort of standard extraction procedure applicable across laboratories is challenging. Laboratories might have to establish calibration functions for their specific extraction system for each natural soil type, individually.

BACKGROUND: The flux of absorbed cholesterol is a controlling element in the regulation of cholesterol biosynthesis and catabolism. A review of 5 published methods to measure cholesterol absorption is presented, including 2 dual stable isotope approaches. The continuous dual isotope feeding procedure is accurate, but only suitable for small-scale studies. The blood-based dual stable isotope technique is the least invasive and complex procedure, but leads to large variations in individual (90%) and mean population values (24%-70%) for healthy subjects. The results may be partly determined by the experimental and analytical procedures.SOURCES OF MATERIAL: Fifteen blood-based dual stable isotope studies published between 1993 and 2013 have been analyzed. The results were related to the methodologies applied and evidence was sought for accordance to the test principles.FINDINGS: Seven different isotopic tracers, 3 cholesterol subcompartments in blood, and 6 mass spectrometry techniques were applied. The oral and intravenous test formulations were presented in only 1 study. Time points for blood sampling and methodologies for blood sample preparation and analysis were highly variable. No definite proofs were supplied for the fates of the oral and intravenous cholesterol tracers. Isotope enrichment measurements in free and total cholesterol in plasma and erythrocytes were never compared. Fractional cholesterol absorption rate values depend strongly on the mass spectrometry methodology. Dual-inlet isotope ratio mass spectrometry appears to be the method of choice.CONCLUSIONS: Dual stable isotope approaches require validation and standardization of administration and analysis procedures. A control group must always be included to correct for methodological differences. (C) 2015 National Lipid Association. All rights reserved.

The doubly labeled water (DLW) technique is used to assess metabolic rate (MR) in free-living conditions. We investigated whether differences in the nutritional and body adiposity status affect validity of the assessment of CO2production (rCO2) by the DLW technique. To serve this purpose, we compared calculated rCO2by the DLW method to actual CO2production concomitantly measured in an indirect calorimetry setup over a 3-day period in mice fed with a low-fat (LF) diet or an obesogenic high-fat/high-sucrose (HF) diet. To uncover a potential effect of body composition on DLW accuracy, the HF-fed group was further subdivided in a diet-induced obesity-prone (DIO) and diet-induced obesity-resistant (DR) group. Furthermore, we assessed the influence of different sampling protocols, duration, and methodology of calculation. An excellent match was found between rCO2assessed by the two methods in the LF-fed mice (least discrepancy −0.5 ± 1.1%). In contrast, there was a consistent overestimation of rCO2by the DLW technique in the HF-fed animals compared with actual CO2production independent from body mass gain (least discrepancy DR +15.9 ± 2.2%, DIO +18.5 ± 3.2%). The least discrepancies were found when two-pool model equations and the intercept method were used to calculate the body water pool. Furthermore, the HF group presented different equilibration kinetics of2H and18O and a lower dilution space ratio between the two. We recommend particular caution when using the DLW method for MR assessment in HF-fed animals and potentially humans because of the overestimation of rCO2.

International audience; Tree ring δ18O chronologies from two native species (Fitzroya cupressoides and Nothofagus pumilio) in northern Patagonia were developed to assess their potential for paleoclimate reconstructions. The five annually resolved cellulose δ18O chronologies (two for F. cupressoides and three for N. pumilio) are located on the Andes along the steep west-to-east precipitation gradient. Over the common 60 years long interval, the five site-δ18Ocell chronologies exhibit a strong common signal as indicated by the significant mean intercorrelation (r = 0.61, p \textless 0.05) and the high percentage (65%) of total variance explained by the first empirical orthogonal function. Although correlation analyses reveal that the two mean species-δ18Ocell chronologies are mainly modulated by December\textendashMay temperature, the N. pumilio chronology shows a greater sensitivity to record temperature variations (r = 0.57, p \textless 0.05). The δ18Ocell of N. pumilio contains a regional temperature signal representative of a large area in southern South America under the influence of the Southern Annular Mode. This study indicates that δ18Ocell in N. pumilio is a promising proxy to reconstruct past variations in temperature in South America south of 38°S.

The stable isotope ratios of atmospheric CO(2) ((18)O/(16)O and (13)C/(12)C) have been monitored since 1977 to improve our understanding of the global carbon cycle, because biosphere-atmosphere exchange fluxes affect the different atomic masses in a measurable way. Interpreting the (18)O/(16)O variability has proved difficult, however, because oxygen isotopes in CO(2) are influenced by both the carbon cycle and the water cycle. Previous attention focused on the decreasing (18)O/(16)O ratio in the 1990s, observed by the global Cooperative Air Sampling Network of the US National Oceanic and Atmospheric Administration Earth System Research Laboratory. This decrease was attributed variously to a number of processes including an increase in Northern Hemisphere soil respiration; a global increase in C(4) crops at the expense of C(3) forests; and environmental conditions, such as atmospheric turbulence and solar radiation, that affect CO(2) exchange between leaves and the atmosphere. Here we present 30 years' worth of data on (18)O/(16)O in CO(2) from the Scripps Institution of Oceanography global flask network and show that the interannual variability is strongly related to the El Niño/Southern Oscillation. We suggest that the redistribution of moisture and rainfall in the tropics during an El Niño increases the (18)O/(16)O ratio of precipitation and plant water, and that this signal is then passed on to atmospheric CO(2) by biosphere-atmosphere gas exchange. We show how the decay time of the El Niño anomaly in this data set can be useful in constraining global gross primary production. Our analysis shows a rapid recovery from El Niño events, implying a shorter cycling time of CO(2) with respect to the terrestrial biosphere and oceans than previously estimated. Our analysis suggests that current estimates of global gross primary production, of 120 petagrams of carbon per year, may be too low, and that a best guess of 150-175 petagrams of carbon per year better reflects the observed rapid cycling of CO(2). Although still tentative, such a revision would present a new benchmark by which to evaluate global biospheric carbon cycling models.

We consider a specific accumulation event that occurred in January 2002 in western Dronning Maud Land, Antarctica. Snow samples were obtained a few days after accumulation. We combine meteorological analyses and isotopic modelling to describe the isotopic composition of moisture during transport. Backward trajectories were calculated, based on European Centre for Medium-Range Weather Forecasts operational archive data so that the history of the air parcels transporting water vapour to the accumulation site could be reconstructed. This trajectory study showed that the air masses were not (super)saturated along most of the transport path, which is in contrast with assumptions in Lagrangian fractionation models and probably true for most precipitation events in Antarctica. The modelled fractionation along the trajectories was too limited to explain the measured isotopic content of the snow. It is shown that the observed isotopic composition of precipitation resulted from fractionation of initially more depleted water. This lower initial isotopic composition of water vapour might result from atmospheric mixing with more depleted air along the trajectory or from earlier condensation cycles, not captured by the trajectories. This is in accordance with isotope fields resulting from general circulation models, indicating a gradient in isotopic composition from the Equator to Antarctica.

Accurate chronologies are essential for linking palaeoclimate archives. Carbon-14 wiggle-match dating was used to produce an accurate chronology for part of an early Holocene peat sequence from the Borchert (The Netherlands). Following the Younger Dryas-Preboreal transition, two climatic shifts could be inferred. Around 11 400 cal. yr BP the expansion of birch (Betula) forest was interrupted by a dry continental phase with dominantly open grassland vegetation, coeval with the PBO (Preboreal Oscillation), as observed in the GRIP ice core. At 11 250 cal. yr BP a sudden shift to a humid climate occurred. This second change appears to be contemporaneous with: (i) a sharp increase of atmospheric C-14; (ii) a temporary decline of atmospheric CO2; and (iii) an increase in the GRIP Be-10 flux. The close correspondence with excursions of cosmogenic nuclides points to a decline in solar activity, which may have forced the changes in climate and vegetation at around 11 250 cal. yr BP. Copyright (C) 2004 John Wiley Sons, Ltd.

BACKGROUND: The flux of absorbed cholesterol is a controlling element in the regulation of cholesterol biosynthesis and catabolism. A review of 5 published methods to measure cholesterol absorption is presented, including 2 dual stable isotope approaches. The continuous dual isotope feeding procedure is accurate, but only suitable for small-scale studies. The blood-based dual stable isotope technique is the least invasive and complex procedure, but leads to large variations in individual (90%) and mean population values (24%-70%) for healthy subjects. The results may be partly determined by the experimental and analytical procedures. SOURCES OF MATERIAL: Fifteen blood-based dual stable isotope studies published between 1993 and 2013 have been analyzed. The results were related to the methodologies applied and evidence was sought for accordance to the test principles. FINDINGS: Seven different isotopic tracers, 3 cholesterol subcompartments in blood, and 6 mass spectrometry techniques were applied. The oral and intravenous test formulations were presented in only 1 study. Time points for blood sampling and methodologies for blood sample preparation and analysis were highly variable. No definite proofs were supplied for the fates of the oral and intravenous cholesterol tracers. Isotope enrichment measurements in free and total cholesterol in plasma and erythrocytes were never compared. Fractional cholesterol absorption rate values depend strongly on the mass spectrometry methodology. Dual-inlet isotope ratio mass spectrometry appears to be the method of choice. CONCLUSIONS: Dual stable isotope approaches require validation and standardization of administration and analysis procedures. A control group must always be included to correct for methodological differences. (C) 2015 National Lipid Association. All rights reserved.

The isotope O-18 in CO2 is of particular interest in studying the global carbon cycle because it is sensitive to the processes by which the global land biosphere absorbs and respires CO2. Carbon dioxide and water exchange isotopically both in leaves and in soils, and the O-18 character of atmospheric CO2 is strongly influenced by the land biota, which should constrain the gross primary productivity and total respiration of land ecosystems, In this study we calculate the global surface fluxes of O-18 for vegetation and soils using the SiB2 biosphere model coupled with the Colorado State University general circulation model. This approach makes it possible to use physiological variables that are consistently weighted by the carbon assimilation rate and integrated through the vegetation canopy, We also calculate the air-sea exchange of O-18 and the isotopic character of fossil emissions and biomass burning. Global mean values of the isotopic exchange with each reservoir are used to close the global budget of O-18 in CO2 results confirm the fact that the land biota exert a dominant control on the delta(18)O of the atmospheric reservoir, At the global scale, exchange with the canopy produces an isotopic enrichment of CO2, whereas exchange with soils has the opposite effect.

International audience; Concern exists about the suitability of laser spectroscopic instruments for the measurement of the O-18/O-16 and H-2/H-1 values of liquid samples other than pure water. It is possible to derive erroneous isotope values due to optical interference by certain organic compounds, including some commonly present in ecosystem-derived samples such as leaf or soil waters. Here we investigated the reliability of wavelength-scanned cavity ring-down spectroscopy (CRDS) O-18/O-16 and H-2/H-1 measurements from a range of ecosystem-derived waters, through comparison with isotope ratio mass spectrometry (IRMS). We tested the residual of the spectral fit S-r calculated by the CRDS instrument as a means to quantify the difference between the CRDS and IRMS delta-values. There was very good overall agreement between the CRDS and IRMS values for both isotopes, but differences of up to 2.3 parts per thousand (delta O-18 values) and 23 parts per thousand (delta H-2 values) were observed in leaf water extracts from Citrus limon and Alnus cordata. The S-r statistic successfully detected contaminated samples. Treatment of Citrus leaf water with activated charcoal reduced, but did not eliminate, delta H-2(CRDS)-delta H-2(IRMS) linearly for the tested range of 0-20 % charcoal. The effect of distillation temperature on the degree of contamination was large, particularly for delta H-2 values but variable, resulting in positive, negative or no correlation with distillation temperature. S-r and delta(CRDS) - delta(IRMS) were highly correlated, in particular for delta H-2 values, across the range of samples that we tested, indicating the potential to use this relationship to correct the delta-values of contaminated plant water extracts. We also examined the sensitivity of the CRDS system to changes in the temperature of its operating environment. We found that temperature changes >= 4 degrees C for delta O-18 values and >= 10 degrees C for delta H-2 values resulted in errors larger than the CRDS precision for the respective isotopes and advise the use of such instruments only in sufficiently temperature-stabilised environments. Copyright (C) 2011 John Wiley & Sons, Ltd.

During a campaign lasting from 27 October to 21 November 2010, sixty-one water samples were taken from the Kupa River, the catchment of which is about ten thousand square kilometres in size. Due to the fact that the upper tributaries of e.g. the ˇCabranka-, Dobra-, Korana-, Mrežnica- and Petrinjˇcica River comprise karstified Mesozoic carbonate formations, the hydrogeologic catchment of Kupa River extends the hydrologic one by far. The upper Kupa River is mainly charged by springs from big karst reservoirs in the Gorski Kotar mountain range, where a mean groundwater residence time of up to one year has to be considered. The rapid increase of discharge of these tributary rivers results from the rapid increase of discharge of karst wells after melting in springtime as well as from storm events. In general, the minimum mean discharge for all hydrographs in July reveals a dry summer season, with the maximum discharge in August/September resulting from an increase in precipitation. We interpret the d O-18 values of the ˇCabranka River (of about -8, 07h as signals from maritime precipitation in this karstified catchment area. The d O-18 value of upper Kupa River diminishes along its course from -8, 09h near Osilnica to -9, 06h west of Karlovac. After the inflow of tributaries south of Karlovac, the oxygen isotope ratio of Kupa River water reveals a significant change because the d O-18 values of the Dobra-, Korana- and Mrežnica River range from -10, 45h to -9, 58h . Due to the fact that the catchment of Dobra- and Korana River rises between 400 and 880 metres, we interpret the lower d O-18 values of river waters from recharge areas at those low mean altitudes as not caused by an altitude effect, but instead by precipitation out of more continental air masses. Our interpretation of stable isotope ratios in river waters is based on the relation between the weighted mean d O-18 and the altitude obtained from stations of the Global Network of Isotopes in Precipitation (GNIP), revealing an approximate vertical d O-18 gradient of -0, 30h per 100 m, as reported by Vreˇca et al. (2006). In addition, this stable isotope data for the GNIP station Zavižan predominantly indicates precipitation from the Adriatic coast, in contrary to the GNIP station Zagreb, the precipitation of which is more influenced by continental air masses. Due to the lack of local precipitation isotope data in the Kupa drainage basin it is not possible to directly analyse the modification of the isotopic signature and its temporal variation in river waters. To sum up, the isotopic composition of river waters in the Kupa Basin is controlled by two factors: the mean altitude of the recharge areas, and differences in the isotope composition of air moisture of more maritime or more continental influence. Along with use for hydrological investigations, the presented isotope data set can serve as a base line of isotope data for assessing future climate impacts within the Kupa Basin, such as temperature changes and change of precipitation distribution. Vreˇca, P., Broni´c, I. K., Horvatinˇci´c, N., Baresi´c, J. (2006): Isotopic characteristics of precipitation in Slovenia and Croatia: Comparison of continental and marine stations.- Journal of Hydrology, 330, 457-469.

Conference: 6th Congress of the French-Society-of-Stables-Isotopes Location: ENSAT Sch, Ecolab Lab, Toulouse, FRANCE Date: OCT 26-29, 2010; International audience; We have used a high-precision, easy, low-cost and rapid method of oxygen isotope analysis applied to various O-bearing matrices, organic and inorganic (sulfates, nitrates and phosphates), whose (18)O/(16)O ratios had already been measured. It was first successfully applied to (18)O analyses of natural and synthetic phosphate samples. The technique uses high-temperature elemental analysis-pyrolysis (EA-pyrolysis) interfaced in continuous-flow mode to an isotope ratio mass spectrometry (IRMS) system. Using the same pyrolysis method we have been able to generate a single calibration curve for all those samples showing pyrolysis efficiencies independent of the type of matrix pyrolysed. We have also investigated this matrix-dependent pyrolysis issue using a newly developed pyrolysis technique involving 'purge-and-trap' chromatography. As previously stated, silver phosphate being a very stable material, weakly hygroscopic and easily synthesized with predictable (18)O/(16)O values, could be considered as a good candidate to become a reference material for the determination of (18)O/(16)O ratios by EA-pyrolysis-IRMS.

Combined oxygen (O) and nitrogen (N) stable isotope analyses are commonly used in the source determination of nitrate . The source and fate of are studied based on distinct O and N isotopic signatures (d18O and d15N) of various sources and isotopic effects during transformation processes, which differ between sources like fertilizer, atmospheric deposition, and microbial production (nitrification). Isotopic fractionation during production and consumption of further affects the d18O and d15N signal. Regarding the d18O in particular, biochemical O exchange between O from and H2O is implicitly assumed not to affect the d18O signature of . This study aimed to test this assumption in soil-based systems. In a short (24 h) incubation experiment, soils were treated with artificially 18O and 15N enriched . Production of from nitrification during the incubation would affect both the 18O and the 15N enrichment. Oxygen exchange could therefore be studied by examining the change in 18O relative to the 15N. In two out of the three soils, we found that the imposed 18O enrichment of the declined relatively more than the imposed enrichment. This implies that O exchange indeed affected the O isotopic signature of , which has important implications for source determination studies. We suggest that O exchange between and H2O should be taken into consideration when interpreting the O isotopic signature to study the origin and fate of in ecosystems. Highlights ¿ The oxygen isotopic signature of nitrate is commonly used to study its source and fate in ecosystems. ¿ The effect of oxygen exchange is in such studies generally not taken into account. ¿ We used a novel ‘enrichment ratio’ approach to evaluate changes the isotopic signature of NO3. ¿ Our study shows that oxygen exchange can affect the oxygen isotopic signature of nitrate in soils.

International audience; Water vapor isotopes represent an innovative and excellent tool for understanding complex mechanisms in the atmospheric water cycle over different time scales, and they can be used for a variety of applications in the fields of paleoclimatology, hydrology, oceanography, and ecology. We use an ultrasensitive near‐infrared spectrometer, originally designed for use on airborne platforms in the upper troposphere and lower stratosphere, to measure the water deuterium and oxygen‐18 isotope ratios in situ, in ground‐level tropospheric moisture, with a high temporal resolution (from 300 s down to less than 1 s). We present some examples of continuous monitoring of near‐surface atmospheric moisture, demonstrating that our infrared laser spectrometer could be used successfully to record high‐concentration atmospheric water vapor mixing ratios in continuous time series, with a data coverage of ∼90%, interrupted only for daily calibration to two isotope ratio mass spectrometry–calibrated local water standards. The atmospheric data show that the water vapor isotopic composition exhibits a high variability that can be related to weather conditions, especially to changes in relative humidity. Besides, the results suggest that observed spatial and temporal variations of the stable isotope content of atmospheric water vapor are strongly related to water vapor transport in the atmosphere.

Internationally distributed organic and inorganic oxygen isotopic reference materials have been calibrated by six laboratories carrying out more than 5300 measurements using a variety of high-temperature conversion techniques (HTC)a in an evaluation sponsored by the International Union of Pure and Applied Chemistry (IUPAC). To aid in the calibration of these reference materials, which span more than 125 per thousand, an artificially enriched reference water (delta(18)O of +78.91 per thousand) and two barium sulfates (one depleted and one enriched in (18)O) were prepared and calibrated relative to VSMOW2b and SLAP reference waters. These materials were used to calibrate the other isotopic reference materials in this study, which yielded: Reference material delta(18)O and estimated combined uncertainty IAEA-602 benzoic acid+71.28 +/- 0.36 per thousand USGS 35 sodium nitrate+56.81 +/- 0.31 per thousand IAEA-NO-3 potassium nitrate+25.32 +/- 0.29 per thousand IAEA-601 benzoic acid+23.14 +/- 0.19 per thousand IAEA-SO-5 barium sulfate+12.13 +/- 0.33 per thousand NBS 127 barium sulfate+8.59 +/- 0.26 per thousand VSMOW2 water 0 per thousand IAEA-600 caffeine-3.48 +/- 0.53 per thousand IAEA-SO-6 barium sulfate-11.35 +/- 0.31 per thousand USGS 34 potassium nitrate-27.78 +/- 0.37 per thousand SLAP water-55.5 per thousand The seemingly large estimated combined uncertainties arise from differences in instrumentation and methodology and difficulty in accounting for all measurement bias. They are composed of the 3-fold standard errors directly calculated from the measurements and provision for systematic errors discussed in this paper. A primary conclusion of this study is that nitrate samples analyzed for delta(18)O should be analyzed with internationally distributed isotopic nitrates, and likewise for sulfates and organics. Authors reporting relative differences of oxygen-isotope ratios (delta(18)O) of nitrates, sulfates, or organic material should explicitly state in their reports the delta(18)O values of two or more internationally distributed nitrates (USGS 34, IAEA-NO-3, and USGS 35), sulfates (IAEA-SO-5, IAEA-SO-6, and NBS 127), or organic material (IAEA-601 benzoic acid, IAEA-602 benzoic acid, and IAEA-600 caffeine), as appropriate to the material being analyzed, had these reference materials been analyzed with unknowns. This procedure ensures that readers will be able to normalize the delta(18)O values at a later time should it become necessary.The high-temperature reduction technique for analyzing delta(18)O and delta(2)H is not as widely applicable as the well-established combustion technique for carbon and nitrogen stable isotope determination. To obtain the most reliable stable isotope data, materials should be treated in an identical fashion; within the same sequence of analyses, samples should be compared with working reference materials that are as similar in nature and in isotopic composition as feasible.

ispartof: Rapid communications in mass spectrometry vol:21 issue:8 pages:1475-1478 ispartof: location:England status: published

International audience; Due to its resistance to oxidation, TaSiN is a promising candidate as an electrically conductive barrier layer for integration of high permittivity oxides in advanced memory devices. In this study we report on the properties of TaSiN thin films deposited by reactive magnetron sputtering of a TaSi2 target in an Ar/N-2 atmosphere. We especially focus on the influence of deposition parameters (pressure and power density) on TaSiN film properties. To study oxidation resistance, films are processed by rapid thermal annealing in O-18(2) at 650 degrees C. The concentration depth profiles of O-18 were measured via the narrow resonance of O-18(p,alpha)N-15 at 151 keV (FWHM = 100 eV). Whatever the power density, films deposited above 2 Pa are porous and exhibit high resistivity. Ta26Si47N27 deposited at 0.5 Pa with a power density of 2.65 W/cm(2) exhibits high density, low resistivity, and good oxidation resistance. (c) 2006 Elsevier B.V. All rights reserved.

The isotopic composition of the rainfall in northwestern Sicily (Italy, central Mediterranean) was investigated in the period February 2002 to March 2003. A rain gauge network was installed and sampled monthly. The monthly values of the D and 18O ratios showed a wide range that reflected seasonal climatic variations. Mean weighted values were used to define an isotopic model of precipitation. Temporal variations in deuterium excess were also investigated. Using mean volume weighted values, the Local Meteoric Water Line (LMWL) can be represented by the equation: δD = 4.7δ18O - 8.2 (r2 = 0.96). Deuterium excess (d = δD - 8δ18O) was found to be strongly related to orography. The coastline samples were characterized by mean weighted deuterium excess values close to 12.5‰ samples from inland areas showed values of 169‰, while samples taken from the main reliefs showed values close to 19%· In inland areas, isotopic exchange between raindrops and moisture could shift the deuterium excess values slightly. On the higher reliefs, the interaction between falling raindrops and orographic clouds could shift the deuterium excess values significantly. The low slope of the LMWL could be referred to the high deuterium excess values of the higher sites and is related to orographic precipitation rather than to evaporation processes during the fall of the raindrops. The results obtained suggest that local orographic features may significantly change the isotopic composition of precipitation. Copyright 2006 by the American Geophysical Union.

Sogenannte Multi-Tracer-Studien sind eine effektive Methode um die Fließbedingungen von Grund- wässern zu bestimmen. Stabile und radioaktive Isotope sowie gasförmige Spurenstoffe wurden zu- sammen mit wasserchemischen Untersuchungen angewandt, um die mittlere Verweilzeit, Herkunft, Mischungstypen von Grundwässern sowie die Regionen der Grundwasserneubildung abzuschätzen. Verschiedene Methoden wurden zur Grundwasserdatierung verwendet (Tritium, C-14, FCKW-11, FCKW-12 und FCKW-113). Tritium lieferte Verweilzeiten von fast null bis größer 50 Jahre für „Piston Flow“ und 73 bis größer 300 Jahre für das Exponentialmodell. Der Vergleich zwischen H-3 und FCKW offenbarte große Abweichungen der berechneten „Grundwasseralter“. Die Diskrepanz könnte mit der Anreicherung der FCKWs durch Pumpen oder dem Bewässerungsrückfluss begründet werden. Trotzdem konnten die FCKWs zur Abschätzung des Grundwasserfließmodells herangezogen werden, wobei das Exponentialmodell die Fließbedingungen im Untersuchungsgebiet am besten beschreibt. Die Abschätzung der mittleren Verweilzeiten mit Hilfe von Radiokohlenstoff erwies sich aufgrund großer Unsicherheiten in der Abschätzung der delta C-13 - Werte für Bodenluft und Karbonate als sehr problematisch. Eine qualitative Betrachtung der C-14 - Konzentrationen lässt allerdings in einigen Fällen die Existenz von fossilen Wässern mit Verweilzeiten von mehreren tausend Jahren erkennen. Die Interpretation der chemischen Analysen und des Strontiums offenbart die Gruppierung der Mehrheit der Proben in zwei Grundwassertypen. Ein Typ ist überwiegend in den Randbereichen des Untersuchungsgebietes zu finden während der zweite Wassertyp im Zentrum des Beckens verteilt ist. Grundwassermischungstypen mit Hilfe von Strontiumisotopenverhältnissen zu erkennen erwies sich als schwierig, da die hohen Strontiumkonzentrationen in den Karbonaten der Sedimente die Unterschiede der Sr-87 / Sr-86 - Signaturen verschiedener Grundwässer überdeckten. Deuterium und O-18 zeigten Verdunstungseffekte im Grundwasser auf, das möglicherweise größere Anteile an Paläowasser hat. Der Vergleich mit Daten eines früheren Berichtes lässt eine zunehmende Anreicherung von H-2 and O-18 erkennen was mit dem Rückfluss von Bewässerungswasser begründet wird. Die Chloridmassenbilanzmethode wurde eingesetzt, um die Regionen der Grundwasserneubildung zu erkennen, die in den Randbereichen des Untersuchungsgebietes zu finden sind. Die höchsten Neubil- dungswerte zeigten dabei die Sierra de Guanajuato und die Erhebungen im Osten und Süden. Weil zur Berechnung nur unzureichende Chloridmessungen im Niederschlag zur Verfügung standen, konn- ten die Ergebnisse lediglich qualitativ bewertet werden., Multitracer studies are an effective tool to determine flow conditions and mean residence times of groundwater. Stable and radioactive isotopes and gaseous tracers together with water chemistry are used to estimate mean residence time, origin and mixing of groundwaters and recharge regions in the aquifer of Silao-Romita. To determine residence times, different methods were applied (tritium, C-14, CFC-11, CFC-12 and CFC-113). Tritium yielded mean residence times of almost zero to more than 50 years for piston flow and 73 to more than 300 years for the exponential model. Comparing tritium and CFC “ages”, large differences became apparent which may be due to enrichment of CFCs caused by pumping or possi- ble irrigation return flow. Nonetheless CFCs provided plausible information to determine the ground- water flow model. The exponential model (EM) appeared to be most appropriate. The determination of mean residence times by radiocarbon was very problematic due to huge uncertainties in estimating delta C-13 of soil air and carbonates. A qualitative estimation revealed in some cases the existence of fossil waters with mean residence times of several thousand years. The interpretation of chemical analyses and strontium showed a grouping of the majority of the sam- ples into two types of groundwater. One is primarily present at the margins of the study area and the other in the centre of the basin. A detection of mixtures by strontium isotope ratios was problematic due to the high strontium content of the carbonates in the sediments which masks possible differences in Sr-87 / Sr-86 signatures of different groundwaters. Using H-2 and O-18 revealed evaporative effects in the extracted groundwater which possibly contains larger proportions on paleowaters. A comparison with data of a former report shows increasingly en- riched values which are attributed to irrigation return flow. Chloride Mass Balance (CMB) was applied to identify recharge regions which are at the margins of the study area. The Sierra de Guanajuato and the hills in the east and south showed the highest recharge values. Due to poor precipitation data of chloride these values were not reliable and interpretation was done qualitatively., research

The highest oxygen isotope ratios ever measured in the Galaxy have been recorded in silica-rich grains from the Murchison meteorite. The excess oxygen-18 and oxygen-17 could be the result of nucleosynthesis in a single exotic star in the early Solar System or evidence of irradiation by highly accelerated particles produced during an active early phase of the Sun. The origins of the building blocks of the Solar System can be studied using the isotopic composition of early planetary and meteoritic material. Oxygen isotopes in planetary materials show variations at the per cent level that are not related to the mass of the isotopes1,2; rather, they result from the mixture of components having different nucleosynthetic or chemical origins1,2,3. Isotopic variations reaching orders of magnitude in minute meteoritic grains are usually attributed to stellar nucleosynthesis before the birth of the Solar System, whereby different grains were contributed by different stars4,5. Here we report the discovery of abundant silica-rich grains embedded in meteoritic organic matter, having the most extreme 18O/16O and 17O/16O ratios observed (both ∼10-1) together with a solar silicon isotopic composition. Both O and Si isotopes indicate a single nucleosynthetic process. These compositions can be accounted for by one of two processes: a single exotic evolved star seeding the young Solar System6, or irradiation of the circumsolar gas by high energy particles accelerated during an active phase of the young Sun. We favour the latter interpretation, because the observed compositions are usually not expected from nucleosynthetic processes in evolved stars, whereas they are predicted by the selective trapping of irradiation products.

We consider a specific accumulation event that occurred in January 2002 in western Dronning Maud Land, Antarctica. Snow samples were obtained a few days after accumulation. We combine meteorological analyses and isotopic modelling to describe the isotopic composition of moisture during transport. Backward trajectories were calculated, based on European Centre for Medium-Range Weather Forecasts operational archive data so that the history of the air parcels transporting water vapour to the accumulation site could be reconstructed. This trajectory study showed that the air masses were not (super)saturated along most of the transport path, which is in contrast with assumptions in Lagrangian fractionation models and probably true for most precipitation events in Antarctica. The modelled fractionation along the trajectories was too limited to explain the measured isotopic content of the snow. It is shown that the observed isotopic composition of precipitation resulted from fractionation of initially more depleted water. This lower initial isotopic composition of water vapour might result from atmospheric mixing with more depleted air along the trajectory or from earlier condensation cycles, not captured by the trajectories. This is in accordance with isotope fields resulting from general circulation models, indicating a gradient in isotopic composition from the Equator to Antarctica.

The isotope O-18 in CO2 is of particular interest in studying the global carbon cycle because it is sensitive to the processes by which the global land biosphere absorbs and respires CO2. Carbon dioxide and water exchange isotopically both in leaves and in soils, and the O-18 character of atmospheric CO2 is strongly influenced by the land biota, which should constrain the gross primary productivity and total respiration of land ecosystems, In this study we calculate the global surface fluxes of O-18 for vegetation and soils using the SiB2 biosphere model coupled with the Colorado State University general circulation model. This approach makes it possible to use physiological variables that are consistently weighted by the carbon assimilation rate and integrated through the vegetation canopy, We also calculate the air-sea exchange of O-18 and the isotopic character of fossil emissions and biomass burning. Global mean values of the isotopic exchange with each reservoir are used to close the global budget of O-18 in CO2 results confirm the fact that the land biota exert a dominant control on the delta(18)O of the atmospheric reservoir, At the global scale, exchange with the canopy produces an isotopic enrichment of CO2, whereas exchange with soils has the opposite effect.

D2O and H218O are often used as tracers for the determination of total body water (TBW). For newborn infants, the commonly used noninvasive method has not been validated. In this study TBW was calculated from D2O concentrations in blood and compared with TBW calculated from D2O concentrations in urine. TBW calculated from all urine portions voided at least 6 h after D2O administration on average was 1.0% lower. TBW calculated from only three urine portions voided 6, 12, and 24 h after D2O administration was 0.6% (mean) lower compared to TBW calculated from D2O concentrations in blood. This study indicates that the noninvasive method to measure TBW can be considered a reliable method when used in newborn infants.