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1
Fitzsimons, I. C. W., B. Harte, and R. M. Clark. "SIMS stable isotope measurement: counting statistics and analytical precision." Mineralogical Magazine 64, no. 1 (February 2000): 59–83. http://dx.doi.org/10.1180/002646100549139.
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AbstractAnalytical precision is vital in the interpretation of stable isotope data collected by secondary ion mass spectrometry (SIMS) given the small analysis volumes and the small magnitude of natural isotopic variations. The observed precision of a set of measurements is represented by the standard deviation(precision of an individual measurement) or the standard error of the mean (precision of the mean value). The SIMS data show both systematic variations with time and random Poisson variability, but the former largely cancel out when data for two different isotopes are expressed as a ratio. The precision of a SIMS isotope ratio routinely matches that predicted by Poisson counting statistics and can approach that of conventional bulk analysis techniques for counting times of several hours. All sample analyse must be calibrated for instrumental mass fractionation using SIMS analyses of a standard material. There is often a gradual drift in the mass fractionation with time, but this can be modelled by least-squares regression of the standard isotope ratios. Drift in the sample analyses is eliminated by using the relevant point on this regression line to calibrate each sample. The final precision of a corrected isotope ratio must take into account the scatter in both the sample and the standard data.
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Halley, Duncan J., Masao Minagawa, Mauri Nieminen, and Eldar Gaare. "Preservation in 70% ethanol solution does not affect δ13C and δ15N values of reindeer blood samples – relevance for stable isotope studies of diet." Rangifer 28, no. 1 (April 29, 2008): 9. http://dx.doi.org/10.7557/2.28.1.146.
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We compared duplicate samples of whole blood samples from 18 reindeer that were preserved either by immediate freezing or by immersion in 70 % ethanol. All samples were dried at 60 °C, powdered, treated with 1:1 chloroform: methanol, and dried again before isotope analysis. There were no differences in the values of δ13C and δ15N between the methods of preservation. Isotopic differences were absolutely small (δ13C = 0.1±0.10/00; δ15N=0.2±0.20/00), random in direction, and within the limits of analytical precision for the mass spectrometer. Preservation in ethanol thus appears to be an effective and efficient method for preserving blood samples for stable isotope analysis under field conditions. Abstract in Norwegian / Sammendrag:Konservering av blodprøver fra rein i 70% etanolløsning påvirker ikke verdiene av δ13C and δ15N–verdiene og er en fullgod metode for analyse av stabile isotoperVi sammenlignet to og to prøver av blodprøver fra 18 reinsdyr. Prøvene var enten konservert ved umiddelbar frysing eller ved bruk av 70% etanol. Alle prøver ble tørket ved 60 °C, pulverisert og behandlet med kloroform:metanol i forholdet 1:1. Til slutt ble de tørket på nytt før gjennomføring av isotopanalysen. Vi fant ingen forskjell i verdiene av δ13C and δ15N mellom de to konserveringsmetodene. I absolutte verdier var isotopforskjellene små (δ13C = 0.1±0.1 0/00; δ15N=0.2±0.2 0/00). Forskjellene var tilfeldige og innenfor grensene for massespektrometerets presisjon. Bruk av etanol framstår som en effektiv og fullgod metode til konservering av blodprøver for analyse av stabile isotoper under feltforhold.
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Dietermann, N., and M. Weiler. "Spatial distribution of stable water isotopes in alpine snow cover." Hydrology and Earth System Sciences 17, no. 7 (July 11, 2013): 2657–68. http://dx.doi.org/10.5194/hess-17-2657-2013.
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<p><strong>Abstract.</strong> The aim of this study was to analyse and predict the mean stable water isotopic composition of the snow cover at specific geographic locations and altitudes. In addition, the dependence of the isotopic composition of the entire snow cover on altitude was analysed. Snow in four Swiss catchments was sampled at the end of the accumulation period in April 2010 and a second time during snowmelt in May 2010 and analysed for stable isotope composition of <sup>2</sup>H and <sup>18</sup>O. The sampling was conducted at both south-facing and north-facing slopes at elevation differences of 100 m, for a total altitude difference of approximately 1000 m. The observed variability of isotopic composition of the snow cover was analysed with stepwise multiple linear regression models. The analysis indicated that there is only a limited altitude effect on the isotopic composition when considering all samples. This is due to the high variability of the isotopic composition of the precipitation during the winter months and, in particular in the case of south-facing slopes, an enrichment of heavy isotopes due to intermittent melting processes. This enrichment effect could clearly be observed in the samples which were taken later in the year. A small altitudinal gradient of the isotopic composition could only be observed at some north-facing slopes. However, the dependence of snow depth and the day of the year were significant predictor variables in all models. This study indicates the necessity to further study the variability of water isotopes in the snow cover to increase prediction for isotopic composition of snowmelt and hence increase model performance of residence time models for alpine areas in order to better understand the accumulation processes and the sources of water in the snow cover of high mountains.</p>
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Stenroth, Patrik, Niklas Holmqvist, Per Nyström, Olof Berglund, Per Larsson, and Wilhelm Granéli. "Stable isotopes as an indicator of diet in omnivorous crayfish (Pacifastacus leniusculus): the influence of tissue, sample treatment, and season." Canadian Journal of Fisheries and Aquatic Sciences 63, no. 4 (April 1, 2006): 821–31. http://dx.doi.org/10.1139/f05-265.
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Stable isotopes have been used to analyse food webs and (or) trace movements of animals for about 30 years. There has been some debate on the use of different tissues and treatments before isotope analysis, as well as on seasonal effects. We found different crayfish (Pacifastacus leniusculus) tissues (muscle, hepatopancreas, exoskeleton, gill, and whole body) to have different isotope values. Lipid extraction made whole-body carbon isotope values higher but had no effect on nitrogen isotope values. Acidification made whole-body isotope values lower. For crayfish, there was no seasonal or interannual variation in isotope values. In contrast to studies based on gut content analysis, we found adult crayfish to be at least as carnivorous as young-of-the-year crayfish. Earlier studies often have assumed that each food source contributes both nitrogen and carbon in equal proportions. Omnivores do not fit easily into this view. We suggest that nitrogen and carbon in an organism could come from different sources. Adopting this view for a pond food web could render crayfish both predators and detritivores as crayfish prey on nitrogen sources (other invertebrates) and consume large amounts of detritus to satisfy their carbon demand.
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Laepple, Thomas, Thomas Münch, Mathieu Casado, Maria Hoerhold, Amaelle Landais, and Sepp Kipfstuhl. "On the similarity and apparent cycles of isotopic variations in East Antarctic snow pits." Cryosphere 12, no. 1 (January 17, 2018): 169–87. http://dx.doi.org/10.5194/tc-12-169-2018.
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Abstract. Stable isotope ratios δ18O and δD in polar ice provide a wealth of information about past climate evolution. Snow-pit studies allow us to relate observed weather and climate conditions to the measured isotope variations in the snow. They therefore offer the possibility to test our understanding of how isotope signals are formed and stored in firn and ice. As δ18O and δD in the snowfall are strongly correlated to air temperature, isotopes in the near-surface snow are thought to record the seasonal cycle at a given site. Accordingly, the number of seasonal cycles observed over a given depth should depend on the accumulation rate of snow. However, snow-pit studies from different accumulation conditions in East Antarctica reported similar isotopic variability and comparable apparent cycles in the δ18O and δD profiles with typical wavelengths of ∼ 20 cm. These observations are unexpected as the accumulation rates strongly differ between the sites, ranging from 20 to 80 mm w. e. yr−1 ( ∼ 6–21 cm of snow per year). Various mechanisms have been proposed to explain the isotopic variations individually at each site; however, none of these are consistent with the similarity of the different profiles independent of the local accumulation conditions.Here, we systematically analyse the properties and origins of δ18O and δD variations in high-resolution firn profiles from eight East Antarctic sites. First, we confirm the suggested cycle length (mean distance between peaks) of ∼ 20 cm by counting the isotopic maxima. Spectral analysis further shows a strong similarity between the sites but indicates no dominant periodic features. Furthermore, the apparent cycle length increases with depth for most East Antarctic sites, which is inconsistent with burial and compression of a regular seasonal cycle. We show that these results can be explained by isotopic diffusion acting on a noise-dominated isotope signal. The firn diffusion length is rather stable across the Antarctic Plateau and thus leads to similar power spectral densities of the isotopic variations. This in turn implies a similar distance between isotopic maxima in the firn profiles.Our results explain a large set of observations discussed in the literature, providing a simple explanation for the interpretation of apparent cycles in shallow isotope records, without invoking complex mechanisms. Finally, the results underline previous suggestions that isotope signals in single ice cores from low-accumulation regions have a small signal-to-noise ratio and thus likely do not allow the reconstruction of interannual to decadal climate variations.
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Macaulay, C. I., A. E. Fallick, R. S. Haszeldine, and C. M. Graham. "Methods of laser-based stable isotope measurement applied to diagenetic cements and hydrocarbon reservoir quality." Clay Minerals 35, no. 1 (March 2000): 313–22. http://dx.doi.org/10.1180/000985500546684.
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AbstractThe stable isotopic compositions of diagenetic minerals can provide valuable constraints on the sources, precipitation temperatures and relative timing of cements in reservoir rocks. This type of information is essential when trying to understand and predict the distribution of cements in the subsurface, and their impact on reservoir quality. Conventional isotope methods contribute to answers to many diagenetic problems, but where core or time are scarce, or where good mineral separation is unobtainable, laser-based stable isotope methods offer several advantages. These include the ability to analyse carbonates, sulphides and anhydrite in situ with 50–100 μm resolution, simple and clear sample and analysis viewing optics, savings on sample preparation time and greatly reduced sample size requirements.Diagenetic silicates such as quartz and clay cements cannot be analysed in situ by laser but, where in situ analysis of quartz δ18O is demanded, ion microprobe analysis can provide very high resolution (20–30 μm) capability with a precision of ±1%.
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Osipowicz, Grzegorz, Andrzej Bokiniec, Krzysztof Kurzyk, Daniel Makowiecki, Dorota Bienias, Tomasz Górzyński, Michał Jankowski, et al. "The Late Neolithic sepulchral and ritual place of site 14 in Kowal (Kuyavia, Central Poland)." Praehistorische Zeitschrift 89, no. 2 (June 30, 2014): 261–79. http://dx.doi.org/10.1515/pz-2014-0018.
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Zusammenfassung: Forschungsgegenstand dieses Artikels ist ein Begräbnis- und Ritualplatz der Kugelamphoren-Kultur der Fundstätte 14 in Kowal (Zentral-Polen). Die Stätte umfasst einen Submegalithen sowie einen Ritualplatz mit Tiergräbern und einer menschlichen Bestattung. Der Komplex kann auf die Zeit zwischen 3250/3100 und 2400/2150 v. Chr. datiert werden. Analysen haben gezeigt, dass der Platz über eine lange Zeit benutzt wurde, und dass die durchgeführten Rituale sehr komplex waren. Beweise wurden gefunden, dass an einigen Stellen rituelle Handlungen ohne Unterbrechung über viele Jahre durchgeführt wurden und einzelne Tieropfer und Niederlegungen nur durch einen Zeitraum von wenigen Jahren voneinander getrennt waren. Die Fund-Struktur einiger Gruben zeigt eine sehr penible Organisation des geheiligten Platzes und ermöglicht an einigen Stellen sogar eine Unterscheidung in Nutz- und rituelle Zonen. Weitere wichtige Informationen wurden durch die Untersuchung einer menschlichen Grablege an dieser Stätte gewonnen. Die Analyse der Grabbeigaben hat deren Natur als rituelle Gaben gezeigt; weiter weist sie auf eine dominante Rolle von Tieren im täglichen Leben der verstorbenen Person hin. Wichtige Daten wurden durch die paläo-biologische Untersuchung der menschlichen Knochen gewonnen. Die paläo-serologische Analyse ergab die Blutgruppe der bestatteten Person. Dies ist der erste derartige Nachweis in der Geschichte der europäischen neolithischen Forschung. Bei den Ergebnissen der DNA-Analyse handelt es eines Vertreters der Kugelamphoren-Kultur in der Literatur und zudem um eine von nur wenigen solcher Untersuchungen eines neolithischen Menschen. Einige der nachgewiesenen Allele sind die ältesten Beispiele dieses speziellen Allel-Typs, die in menschlichen Überresten bis heute identifiziert wurden. Die DNA-Analysen belegen eine Laktose-Intoleranz der bestatteten Person, sie legen weiter eine genetische Verwandtschaft mit der Bevölkerung aus der Region des Fruchtbaren Halbmondes nahe. Die Analyse des stabilen Sauerstoff-Isotopen-Verhältnisses zeigt Muster für häufigeren Ortswechsel und das Entwöhnungsalter. Analysen von stabilen Kohlenstoff- und Stickstoff-Isotopen-Verhältnissen haben Rückschlüsse auf die Ernährung ermöglicht; besondere Aufmerksamkeit verdient die Tatsache, dass bis zu 25 % der Kohlenhydrat-haltigen Nahrung aus Hirse bestanden hat. Das ist der früheste Isotopen-gestützte Nachweis von Hirse in der menschlichen Ernährung in Mitteleuropa. Résumé: Le site 14 de Kowal en Pologne centrale, un complexe rituel appartenant à la culture des amphores globulaires, forme le sujet de cet article. Le site comporte un sub-mégalithe, une structure rituelle avec des dépôts d’animaux et une sépulture humaine. Il fut occupé pendant une longue période allant de 3250/3100 à 2400/2150 av. J.-C. et les rituels étaient complexes: certains furent célébrés au même endroit pendant longtemps, tandis que les sacrifices et dépôts d’animaux n’étaient séparés que par de courts intervalles de peutêtre quelques années. Le remplissage de plusieurs fosses démontre une organisation précise de l’espace sacré, et il a même été possible de faire une distinction entre les actes de déposition rituelle et les dépôts de type utilitaire à l’intérieur de ces fosses. L’étude de la sépulture humaine a également fourni d’importants indices. Il en ressort qu’un individu intentionnellement choisi parmi les membres de ‘l’aristocratie’ locale a été la victime d’un meurtre rituel. L’analyse du mobilier funéraire indique qu’il s’agit d’offrandes rituelles et suggère que les animaux jouaient un rôle déterminant dans la vie de cet individu. L’étude de ses ossements a fourni un important ensemble de données, y compris les résultats d’une analyse sérologique permettant d’identifier – pour la première fois pour le Néolithique européen – le groupe sanguin de cette homme. Dans une étude également pionnière pour la culture des amphores globulaires, l’analyse ADN a permis de décrire la composition génétique d’un de ses membres, une rareté dans les études sur le Néolithique. Certains allèles sont les plus anciens exemplaires d’un type particulier d’allèles jusqu’à présent découvert dans des restes humains. Les données de l’analyse de l’ADN de cet individu suggèrent qu’il était intolérant au lactose et qu’il avait des affinités génétiques avec le Croissant fertile. Les résultats de l’analyse des isotopes stables de l’oxygène peuvent être interprétés soit en termes de mobilité ou de sevrage. Ceux provenant de l’analyse des isotopes stables du carbone et de l’azote nous permettent de reconstruire l’alimentation de notre individu ; en particulier le millet fournissait jusqu’à 25 % de sa consommation en glucides. Ce résultat constitue le premier indice isotopique de la présence du millet dans l’alimentation des populations de l’Europe centrale. Abstract: Site 14 in Kowal (central Poland), a funerary and ritual place of the Globular amphora culture forms the subject of this article. The site includes a sub-megalith, a ritual feature with animal burials and a human burial. The complex can be dated to a period spanning from 3250/3100 to 2400/2150 BC; it was used over a long period, and the rituals carried out were complex. Rituals were performed over many years in certain areas, while individual acts of animal sacrifice and deposition may have been separated by a short interval of just a few years. The fill of some pits shows that the sacred space was carefully organised and it has been possible to distinguish between some utilitarian and ritual deposits within them. Other important information is provided by the study of a human burial discovered at the site. It is possible that a deliberately chosen individual from the tribal ‘aristocracy’ was the victim of a ritual murder. The analysis of the grave goods reveals that they were ritual offerings, and these suggest that animals played a dominant role in the deceased man’s daily life. The study of his bones provides important new insights, including those from a palaeo-serological analysis revealing his blood group, a first in the history of European Neolithic research. The results of DNA analysis constitute the first description of the genetic traits of a representative of the Globular amphora culture, among very few such DNA profiles available for a Neolithic person. Some of the alleles discovered are the oldest examples of particular alleles among those identified in human remains so far. DNA evidence suggests that the individual was lactose intolerant, and it demonstrates a genetic relationship with the Fertile Crescent. The analysis of stable oxygen isotope ratios shows patterns compatible with either residential mobility or weaning age. The analysis of stable carbon and nitrogen isotope ratios allowed us to reconstruct the individual’s diet; particular attention is drawn to the fact that up to 25 % of his carbohydrate diet consisted of millet. This is the earliest isotopic evidence for the presence of millet in the diet of people living in Central Europe.
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van der Wel, L. G., V. Gkinis, V. A. Pohjola, and H. A. J. Meijer. "Snow isotope diffusion rates measured in a laboratory experiment." Journal of Glaciology 57, no. 201 (2011): 30–38. http://dx.doi.org/10.3189/002214311795306727.
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AbstractThe diffusion of stable water isotopes in snow was measured in two controlled laboratory experiments. Two batches of snow of different isotopic composition were stacked alternately with varying layer thicknesses. The stack was stored in a freezer room at constant temperature for several months, and sampled at regular intervals to analyse the diffusion. Measured isotope profiles were fitted to a theoretical model with diffusion length as the fit parameter. In the first experiment, we observed a difference in diffusion rates between layers of different thicknesses, which is likely caused by layers of snow not being in proper contact with each other. In the second experiment we found very good agreement between measurements and model results. The measured diffusivity is compared with theory, in which we mainly focus on the temperature dependence of the ice–vapour fractionation factors. This temperature dependence is slightly different for the different isotopes of water, which leads to a difference in diffusion rates. We illustrate how our set-up can be used to measure the ratio between ice–vapour fractionation factors of oxygen-18 and deuterium, which determine the relation between the difference in diffusion and the firn temperature.
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Dittmann, Anna, Elisabeth Schlosser, Valérie Masson-Delmotte, Jordan G. Powers, Kevin W. Manning, Martin Werner, and Koji Fujita. "Precipitation regime and stable isotopes at Dome Fuji, East Antarctica." Atmospheric Chemistry and Physics 16, no. 11 (June 6, 2016): 6883–900. http://dx.doi.org/10.5194/acp-16-6883-2016.
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Abstract. A unique set of 1-year precipitation and stable water isotope measurements from the Japanese Antarctic station, Dome Fuji, has been used to study the impact of the synoptic situation and the precipitation origin on the isotopic composition of precipitation on the Antarctic Plateau. The Antarctic Mesoscale Prediction System (AMPS) archive data are used to analyse the synoptic situations that cause precipitation. These situations are investigated and divided into five categories. The most common weather situation during a precipitation event is an upper-level ridge that extends onto the Antarctic Plateau and causes strong northerly advection from the ocean. Most precipitation events are associated with an increase in temperature and wind speed, and a local maximum of δ18O. During the measurement period, 21 synoptically caused precipitation events caused 60 % of the total annual precipitation, whereas the remaining 40 % were predominantly attributed to diamond dust. By combining the synoptic analyses with 5-day back-trajectories, the moisture source regions for precipitation events were estimated. An average source region around a latitude of 55° S was found. The atmospheric conditions in the source region were used as initial conditions for running a Rayleigh-type isotopic model in order to reproduce the measured isotopic composition of fresh snow and to investigate the influence of the precipitation source region on the isotope ratios. The model represents the measured annual cycle of δ18O and the second-order isotopic parameter deuterium excess reasonably well, but yields on average too little fractionation along the transport/cooling path. While simulations with an isotopic general circulation model (GCM) (ECHAM5-wiso) for Dome Fuji are on average closer to the observations, this model cannot reproduce the annual cycle of deuterium excess. In the event-based analysis, no evidence of a correlation of the measured deuterium excess with the latitude of the moisture source region or the corresponding conditions was identified. Contrary to the assumption used for decades in ice core studies, a more northerly moisture source does not necessarily mean a larger temperature difference between source area and deposition site, thus a more depleted precipitation in heavy isotopes with a higher deuterium excess.
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Bode, Antonio, and Maria Teresa Alvarez-Ossorio. "Taxonomic versus trophic structure of mesozooplankton: a seasonal study of species succession and stable carbon and nitrogen isotopes in a coastal upwelling ecosystem." ICES Journal of Marine Science 61, no. 4 (January 1, 2004): 563–71. http://dx.doi.org/10.1016/j.icesjms.2004.03.004.
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Abstract Seasonal variations in mesozooplankton (>200 μm) stable carbon and nitrogen isotope abundances were compared with the seasonal species succession pattern off A Coruña (Galicia, NW Spain). Mesozooplankton biomass, numerical abundance, species composition, and natural abundance of stable isotopes, along with water column temperature, salinity, chlorophyll a and dissolved nitrate concentrations, were studied in monthly samples during the years 2000 and 2001 at a coastal station (80-m depth). Biomass and abundance of mesozooplankton followed the annual cycle with maxima in spring and summer (year 2000) and occasionally also in autumn (year 2001). The succession pattern shown by the taxonomic assemblages was recognized in both years of study, despite differences in the timing of upwelling and the large input of continental water during most of 2000. Variations in neither carbon nor nitrogen isotopes were correlated with either abundance or biomass at annual time scales, but heavy isotopes significantly accumulated during periods of zooplankton increase (spring and early summer). The consumption of nitrate during the spring can explain in part the progressive accumulation of heavy nitrogen isotopes during this period. In addition, the abundance of carnivorous zooplankton (mainly carnivorous copepods, siphonophores, and chaetognaths) was linearly related to the increase in heavy isotopes during the spring and, in the case of nitrogen, also during the whole study period. The computed linear relationships between isotope abundances and plankton species composition provided a way to further analyse the pelagic foodweb through the estimation of isotope reference values for primary consumers.
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Meisehen, T., F. Bühler, R. Koppmann, and M. Krebsbach. "An analytical system for the measurement of stable hydrogen isotopes in ambient volatile organic compounds." Atmospheric Measurement Techniques 8, no. 10 (October 23, 2015): 4475–86. http://dx.doi.org/10.5194/amt-8-4475-2015.
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Abstract. Stable isotope measurements in atmospheric volatile organic compounds (VOCs) are an excellent tool to analyse chemical and dynamical processes in the atmosphere. While up to now isotope studies of VOCs in ambient air have mainly focussed on carbon isotopes, we herein present a new measurement system to investigate hydrogen isotope ratios in atmospheric VOCs. This system, consisting of a gas chromatography pyrolysis isotope ratio mass spectrometer (GC-P-IRMS) and a pre-concentration system, was thoroughly characterised using a VOC test mixture. A precision of better than 9 ‰ (in δ 2H) is achieved for n-pentane, 2-methyl-1,3-butadiene (isoprene), n-heptane, 4-methyl-pentane-2-one (4-methyl-2-pentanone), methylbenzene (toluene), n-octane, ethylbenzene, m/p-xylene and 1,2,4-trimethylbenzene. A comparison with independent measurements via elemental analysis shows an accuracy of better than 9 ‰ for n-pentane, n-heptane, 4-methyl-2-pentanone, toluene and n-octane. Above a minimum required pre-concentrated compound mass the obtained δ 2H values are constant within the standard deviations. In addition, a remarkable influence of the pyrolysis process on the isotope ratios is found and discussed. Reliable measurements are only possible if the ceramic tube used for the pyrolysis is sufficiently conditioned, i.e. the inner surface is covered with a carbon layer. It is essential to verify this conditioning regularly and to renew it if required. Furthermore, influences of a necessary H3+ correction and the pyrolysis temperature on the isotope ratios are discussed. Finally, the applicability to measure hydrogen isotope ratios in VOCs at ambient levels is demonstrated with measurements of outside air on 5 different days in February and March 2015. The measured hydrogen isotope ratios range from −136 to −105 ‰ forn-pentane, from −86 to −63 ‰ for toluene, from −39 to −15 ‰ for ethylbenzene, from −99 to −68 ‰ for m/p-xylene and from −45 to −34 ‰ for o-xylene.
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Meisehen, T., F. Bühler, R. Koppmann, and M. Krebsbach. "An analytical system for the measurement of stable hydrogen isotopes in ambient volatile organic compounds." Atmospheric Measurement Techniques Discussions 8, no. 7 (July 10, 2015): 7093–125. http://dx.doi.org/10.5194/amtd-8-7093-2015.
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Abstract. Stable isotope measurements in atmospheric volatile organic compounds (VOC) are an excellent tool to analyse chemical and dynamical processes in the atmosphere. While up to now isotope studies of VOC in ambient air mainly focus on carbon isotopes, we herein present a new measurement system to investigate hydrogen isotope ratios in atmospheric VOC. This system consisting of a GC-P-IRMS (Gas Chromatography Pyrolysis Isotope Ratio Mass Spectrometer) and a preconcentration system was thoroughly characterised using a working standard. A precision of better than 9 ‰ (in δD) is achieved for n-pentane, 2-methyl-1,3-butadiene (isoprene), n-heptane, 4-methyl-pentane-2-one (4-methyl-2-pentanone), methylbenzene (toluene), n-octane, ethylbenzene, m/p-xylene, and 1,2,4-trimethylbenzene. A comparison with independent measurements via elemental analysis shows an accuracy of better than 9 ‰ for n-pentane, n-heptane, 4-methyl-2-pentanone, toluene, and n-octane. Above a compound specific minimum peak area the obtained δD values are constant within the standard deviations. In addition, a remarkable influence of the pyrolysis process on the isotope ratios is found and discussed. Reliable measurements are only possible if the ceramic tube used for the pyrolysis is sufficiently conditioned, i.e. the inner surface is covered with a carbon layer. It is essential to verify this conditioning regularly and to renew it if required. Furthermore, influences of a necessary H3&plus; correction and the pyrolysis temperature on the isotope ratios are discussed. Finally, the applicability to measure hydrogen isotope ratios in VOC at ambient levels is demonstrated with measurements of outside air on five different days in February and March 2015. The measured hydrogen isotope ratios range from −136 to −105 ‰ for n-pentane, from −86 to −63 ‰ for toluene, from −39 to −15 ‰ for ethylbenzene, from −99 to −68 ‰ for m/p-xylene, and from −45 to −34 ‰ for o-xylene.
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Liénart, Camilla, Andrius Garbaras, Susanne Qvarfordt, Jakob Walve, and Agnes M. L. Karlson. "Spatio-temporal variation in stable isotope and elemental composition of key-species reflect environmental changes in the Baltic Sea." Biogeochemistry 157, no. 2 (November 11, 2021): 149–70. http://dx.doi.org/10.1007/s10533-021-00865-w.
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AbstractCarbon and nitrogen stable isotope ratios are increasingly used to study long-term change in food web structure and nutrient cycling. We retrospectively analyse elemental composition (C, N and P) and stable isotopes (δ13C, δ15N) in archived monitoring samples of two important taxa from the bottom of the food web; the filamentous ephemeral macroalgae Cladophora spp. and the blue mussel Mytilus edulis trossulus from three contrasting regions in the Baltic Sea (coastal Bothnian Sea and Baltic Proper, open sea central Baltic). The aim is to statistically link the observed spatial and interannual (8–24 years’ time-series) variability in elemental and isotope baselines with their biomass trends and to the oceanographic monitoring data reflecting the ongoing environmental changes (i.e., eutrophication and climate) in this system. We find clear differences in isotope baselines between the two major Baltic Sea basins. However, the temporal variation in Mytilus δ13C was similar among regions and, at the open sea station, mussels and algae δ13C also correlated over time, likely reflecting a global (Suess) effect, whereas δ15N of both taxa varied with local and regional dissolved nitrogen concentrations in water. δ15N in source amino acids allowed detection of diazotrophic N in Mytilus, which was masked in bulk δ15N. Finally, Cladophora N:P reflected regional nutrient levels in the water while P%, which differed for both taxa, was linked to food quality for Mytilus. This study highlights the potential of a multi-taxa and multi-stable isotope approach to understand nutrient dynamics and monitor long-term environmental changes.
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Moens, Luc, José De Donder, Paul De Paepe, and Julien Van Hende. "Analyse des isotopes stables du carbone et de l'oxygène appliquée à des marbres de Pessinonte (Anatolie Centrale)." Anatolia Antiqua 6, no. 1 (1998): 267–71. http://dx.doi.org/10.3406/anata.1998.901.
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Melody, Carol, Bryan Griffiths, Jens Dyckmans, and Olaf Schmidt. "Stable isotope analysis (δ13C andδ15N) of soil nematodes from four feeding groups." PeerJ 4 (September 1, 2016): e2372. http://dx.doi.org/10.7717/peerj.2372.
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Soil nematode feeding groups are a long-established trophic categorisation largely based on morphology and are used in ecological indices to monitor and analyse the biological state of soils. Stable isotope ratio analysis (13C/12C and15N/14N, expressed asδ13C andδ15N) has provided verification of, and novel insights into, the feeding ecology of soil animals such as earthworms and mites. However, isotopic studies of soil nematodes have been limited to date as conventional stable isotope ratio analysis needs impractically large numbers of nematodes (up to 1,000) to achieve required minimum sample weights (typically >100 µg C and N). Here, micro-sample near-conventional elemental analysis–isotopic ratio mass spectrometry (μEA–IRMS) of C and N using microgram samples (typically 20 µg dry weight), was employed to compare the trophic position of selected soil nematode taxa from four feeding groups: predators (AnatonchusandMononchus), bacterial feeders (PlectusandRhabditis), omnivores (Aporcelaimidae and Qudsianematidae) and plant feeder (Rotylenchus). Free-living nematodes were collected from conventionally and organically managed arable soils. As few as 15 nematodes, for omnivores and predators, were sufficient to reach the 20 µg dry weight target. There was no significant difference inδ15N (p= 0.290) orδ13C (p= 0.706) between conventional and organic agronomic treatments but, within treatments, there was a significant difference in N and C stable isotope ratios between the plant feeder,Rotylenchus(δ15N = 1.08 to 3.22 mUr‰,δ13C = –29.58 to –27.87 mUr) and all other groups. There was an average difference of 9.62 mUr inδ15N between the plant feeder and the predator group (δ15N = 9.89 to 12.79 mUr,δ13C = –27.04 to –25.51 mUr). Isotopic niche widths were calculated as Bayesian derived standard ellipse areas and were smallest for the plant feeder (1.37 mUr2) and the predators (1.73 mUr2), but largest for omnivores (3.83 mUr2). These data may reflect more preferential feeding by the plant feeder and predators, as assumed by classical morphology-based feeding groups, and indicate that omnivory may be more widespread across detritivore groups i.e. bacterial feeders (3.81 mUr2). Trophic information for soil nematodes derived from stable isotope analysis, scaled as finely as species level in some cases, will complement existing indices for soil biological assessment and monitoring, and can potentially be used to identify new trophic interactions in soils. The isotopic technique used here, to compare nematode feeding group members largely confirm their trophic relations based on morphological studies.
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Benbow, Timothy J., Alan R. Hayman, Robert Van Hale, and Russell Frew. "Preparation of aqueous fatty acids for hydrogen and carbon stable isotope analysis by solid phase extraction." Marine and Freshwater Research 64, no. 4 (2013): 294. http://dx.doi.org/10.1071/mf12192.
Full textAbstract:
Stable isotope analyses of fatty acids in environmental waters provides important information as to their source(s). Analysis is often confounded due to low concentrations of fatty acids and/or a complex sample matrix requiring separation of the target analyte. The purpose of this study was to validate a method to extract fatty acids from natural waters using solid phase extraction (SPE) before compound specific isotope analysis (CSIA). Three SPE cartridges and multiple eluting solvents were tested to determine the efficiency, isotopic fractionation, and reproducibility of each extraction technique. Our results indicated that surface-modified styrene divinylbenzene cartridges, when eluted with methanol, caused negligible fractionation of the hydrogen isotopes and minimal fractionation of the carbon isotopes, but that isotopic fractionation occurred when compounds were only partially eluted from SPE cartridges. Compounds were also extracted from landfill leachate using both SPE and liquid–liquid extraction (LLE). The hydrogen isotope composition (δ2H) of compounds extracted from water using either method were within experimental precision and the carbon isotope composition (δ13C) of all but one fatty acid were within experimental precision. Therefore, these experiments prove the aforementioned SPE methods to be a convenient and precise method to extract fatty acids from natural waters before CSIA.
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Du, Kang, Beiying Zhang, and Linjuan Li. "Soil Water Dynamics Under Different Land Uses in Loess Hilly Region in China by Stable Isotopic Tracing." Water 13, no. 2 (January 19, 2021): 242. http://dx.doi.org/10.3390/w13020242.
Full textAbstract:
Exploring soil water dynamics under different land use types is important for water resource management and vegetation restoration in the Loess Plateau. In this study, we investigated the hydrogen and oxygen isotopic compositions of soil water from four different land use types to explore the mechanism of soil water movement and transformation and analyse the influence of land use. The results show that the range of stable isotopes (δD and δ18O) in soil water was smaller than that in precipitation. Values for δD and δ18O in soil water showed relatively similar temporal variation, heavy isotopes were enriched in the soil water in July and depleted in October. Stable isotope values in shallow (<100 cm depth) soil water and deep (>200 cm depth) soil water were low. The δD and δ18O values in woodlands decreased gradually with increasing depth. Across the four land use types, the maximum variation in δD and δ18O was in the shallow depth of the soil profile. Groundwater was recharged mainly from precipitation and then from soil water. The ratio of groundwater recharge by soil water under different land use types followed this rank order: woodland (35.70%) > grassland (31.14%) > shrubland (29.47%) > cropland (29.18%). Matrix flow and preferential flow coexisted during infiltration, and the occurrence of preferential flow was related to the land use type. The main reason for the variation in isotopic composition in soil water is the difference in soil evaporation, which is influenced by different vegetation cover. Owing to the difference in soil evaporation and fractionation, precipitation on cropland, shrubland, and grassland can recharge more soil water than on woodland.
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Mascart, Thibaud, Gilles Lepoint, and Marleen De Troch. "Meiofauna and harpacticoid copepods in different habitats of a Mediterranean seagrass meadow." Journal of the Marine Biological Association of the United Kingdom 93, no. 6 (April 3, 2013): 1557–66. http://dx.doi.org/10.1017/s0025315413000222.
Full textAbstract:
This study investigated whether associated meiobenthic communities, especially harpacticoid copepods, differed amongst habitats. Five pre-defined habitats within and next to the Posidonia oceanica seagrass meadow were sampled: living seagrass canopy leaves (LL), small (SMF) and large (LMF) macrophytodetritus fragment accumulations and sand, bare (BS) and covered (CS). The highest meiofauna abundances were recorded in the BS for the core sampled habitats (BS, CS, SMF and LMF) and in the LMF for seagrass material habitats (SMF, LMF and LL). Harpacticoid copepods were the most abundant taxon in all habitats. The assemblage composition at copepod family level showed two distinct habitats clusters: a leaf (LMF and LL) and a sediment cluster (BS, CS and SMF). Subsequently, stable isotope analyses were conducted to analyse the relationship between copepods and their potential food sources in seagrass material habitats. Based on δ13C isotopic analyses and SIAR mixing model, harpacticoid copepods relied for 70% on epiphytes and for 30% on P. oceanica leaf material in the LMF and LL habitats.
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Sedaghatpour, Fatemeh, and Stein B. Jacobsen. "Magnesium stable isotopes support the lunar magma ocean cumulate remelting model for mare basalts." Proceedings of the National Academy of Sciences 116, no. 1 (December 17, 2018): 73–78. http://dx.doi.org/10.1073/pnas.1811377115.
Full textAbstract:
We report high-precision Mg isotopic analyses of different types of lunar samples including two pristine Mg-suite rocks (72415 and 76535), basalts, anorthosites, breccias, mineral separates, and lunar meteorites. The Mg isotopic composition of the dunite 72415 (δ25Mg = −0.140 ± 0.010‰, δ26Mg = −0.291 ± 0.018‰), the most Mg-rich and possibly the oldest lunar sample, may provide the best estimate of the Mg isotopic composition of the bulk silicate Moon (BSM). This δ26Mg value of the Moon is similar to those of the Earth and chondrites and reflects both the relative homogeneity of Mg isotopes in the solar system and the lack of Mg isotope fractionation by the Moon-forming giant impact. In contrast to the behavior of Mg isotopes in terrestrial basalts and mantle rocks, Mg isotopic data on lunar samples show isotopic variations among the basalts and pristine anorthositic rocks reflecting isotopic fractionation during the early lunar magma ocean (LMO) differentiation. Calculated evolutions of δ26Mg values during the LMO differentiation are consistent with the observed δ26Mg variations in lunar samples, implying that Mg isotope variations in lunar basalts are consistent with their origin by remelting of distinct LMO cumulates.
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Lesser, Michael P., Marc Slattery, and Keir J. Macartney. "Using Stable Isotope Analyses to Assess the Trophic Ecology of Scleractinian Corals." Oceans 3, no. 4 (November 14, 2022): 527–45. http://dx.doi.org/10.3390/oceans3040035.
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Studies on the trophic ecology of scleractinian corals often include stable isotope analyses of tissue and symbiont carbon and nitrogen. These approaches have provided critical insights into the trophic sources and sinks that are essential to understanding larger-scale carbon and nitrogen budgets on coral reefs. While stable isotopes have identified most shallow water (<30 m) corals as mixotrophic, with variable dependencies on autotrophic versus heterotrophic resources, corals in the mesophotic zone (~30–150 m) transition to heterotrophy with increasing depth because of decreased photosynthetic productivity. Recently, these interpretations of the stable isotope data to distinguish between autotrophy and heterotrophy have been criticized because they are confounded by increased nutrients, reverse translocation of photosynthate, and changes in irradiance that do not influence photosynthate translocation. Here we critically examine the studies that support these criticisms and show that they are contextually not relevant to interpreting the transition to heterotrophy in corals from shallow to mesophotic depths. Additionally, new data and a re-analysis of previously published data show that additional information (e.g., skeletal isotopic analysis) improves the interpretation of bulk stable isotope data in determining when a transition from primary dependence on autotrophy to heterotrophy occurs in scleractinian corals.
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Zitek, A., J. Irrgeher, M. Cervicek, M. Horsky, M. Kletzl, T. Weismann, and T. Prohaska. "Individual-specific transgenerational marking of common carp Cyprinus carpio, L., using 86Sr/84Sr double spikes." Marine and Freshwater Research 65, no. 11 (2014): 978. http://dx.doi.org/10.1071/mf13235.
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Transgenerational isotopic marking has been recognised as an efficient tool for mass marking of high numbers of fish larvae by injecting female spawners with enriched isotope solutions. So far, mainly enriched stable barium isotopes have been applied for this purpose. Here, we present an alternative approach for individual-specific transgenerational marking using strontium 86Sr/84Sr double spikes. Four isotonic double-spike solutions with different molar fractions of 86Sr and 84Sr and different total Sr concentrations were administered to four female spawners of common carp, Cyprinus carpio, L., by intraperitoneal injection, and one additional female spawner was injected a blank isotonic solution as control. Otoliths (lapilli) were sampled from juvenile offspring and analysed for their Sr isotopic composition by laser ablation–multi collector–inductively coupled plasma–mass spectrometry. Central otolith regions of the progeny of female carps treated with concentrations of at least 0.45 mg 84Sr kg–1 bodyweight and 2.28 mg 86Sr kg–1 bodyweight showed a significant shift of the absolute 88Sr/86Sr and 88Sr/84Sr isotope ratios from the natural baseline. Isotope pattern deconvolution was successfully applied for the identification of the originally injected 86Sr/84Sr molar fraction ratios of the individual double spikes. Enriched stable Sr isotope double spikes represent an important alternative to enriched stable Ba isotopes for transgenerational marking, especially in freshwater systems.
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Sehrawat, Jagmahender Singh, and Jaspreet Kaur. "Role of stable isotope analyses in reconstructing past life-histories and the provenancing human skeletal remains: a review." Anthropological Review 80, no. 3 (September 1, 2017): 243–58. http://dx.doi.org/10.1515/anre-2017-0017.
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AbstractThis article reviews the present scenario of use of stable isotopes (mainly δ13C, δ15N, δ18O,87Sr) to trace past life behaviours like breast feeding and weaning practices, the geographic origin, migration history, paleodiet and subsistence patterns of past populations from the chemical signatures of isotopes imprinted in human skeletal remains. This approach is based on the state that food-web isotopic signatures are seen in the human bones and teeth and such signatures can change parallely with a variety of biogeochemical processes. By measuring δ13C and δ15N isotopic values of subadult tissues of different ages, the level of breast milk ingestion at particular ages and the components of the complementary foods can be assessed. Strontium and oxygen isotopic analyses have been used for determining the geographic origins and reconstructing the way of life of past populations as these isotopes can map the isotopic outline of the area from where the person acquired water and food during initial lifetime. The isotopic values of strontium and oxygen values are considered specific to geographical areas and serve as reliable chemical signatures of migration history of past human populations (local or non-local to the site). Previous isotopic studies show that the subsistence patterns of the past human populations underwent extensive changes from nomadic to complete agricultural dependence strategies. The carbon and nitrogen isotopic values of local fauna of any archaeological site can be used to elucidate the prominence of freshwater resources in the diet of the past human populations found near the site. More extensive research covering isotopic descriptions of various prehistoric, historic and modern populations is needed to explore the role of stable isotope analysis for provenancing human skeletal remains and assessing human migration patterns/routes, geographic origins, paleodiet and subsistence practices of past populations.
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Uriarte, Amaya, Alberto García, Aurelio Ortega, Fernando De la Gándara, José Quintanilla, and Raúl Laiz-Carrión. "Isotopic discrimination factors and nitrogen turnover rates in reared Atlantic bluefin tuna larvae (Thunnus thynnus): effects of maternal transmission." Scientia Marina 80, no. 4 (November 22, 2016): 447. http://dx.doi.org/10.3989/scimar.04435.25a.
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The use of stable isotope analysis to study animal diets requires estimates of isotopic turnover rates (half time, t50) and discrimination factors (Δ) for an accurate interpretation of trophic patterns. The stable isotopes of carbon and nitrogen were analysed for eggs and reared larvae of Thunnus thynnus, as well as for the different diets supplied during the experiment. The results showed high values of δ15N in eggs and larvae (n=646) until 4 DAH. After this time lapse, the stable isotope values declined progressively until 12 DAH, when notochord flexion began. The δ13C showed an inverse trend, suggesting that maternal inheritance of the stable isotopes is evident until pre-flexion stages. This study proposes a model for estimating maternal isotopic signatures of bluefin broodstock. After notochord flexion, larvae were fed with aquaculture-bred gilthead seabream, which resulted in a rapid increase of bluefin larvae δ15N values together with a rapid decrease in δ13C values. The estimated nitrogen half-time to reach the steady state from the diet was 2.5±0.3 days and the discrimination factor was 0.4±0.3(‰). These results represent the first data set that has allowed isotopic nitrogen turnover rates and discrimination factors of the larval stages of bluefin tuna to be estimated.
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Ubelaker, Douglas H., and Douglas W. Owsley. "Isotopic Evidence for Diet in the Seventeenth-Century Colonial Chesapeake." American Antiquity 68, no. 1 (January 2003): 129–39. http://dx.doi.org/10.2307/3557036.
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Excavations of colonial period sites in Maryland and Virginia have produced human remains dating to the seventeenth century. In this study, we analyze stable isotopes of carbon and nitrogen from these remains to explore aspects of the diets of the individuals represented. Analyses of both stable carbon and nitrogen isotopes were conducted on preserved protein while stable carbon isotope analysis was also conducted on preserved biological apatite. Carbon isotope values (δ13N‰) ranged from -10.5 to -20.5 for collagen and -5.1 to -12.5 for bioapatite. Nitrogen isotope values (δ15N‰) ranged from 9.9 to 14.4. The data suggest dietary diversity among the individuals examined. Three factors contribute to this diversity: the availability of maize, variation in immigration histories of the individuals, and the differing lengths of time they spent in the American colonies.
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Alqahtani, Ali, Kate Heesom, Jonathan L. Bramson, David Curiel, Hideyo Ugai, and David A. Matthews. "Analysis of purified Wild type and mutant adenovirus particles by SILAC based quantitative proteomics." Journal of General Virology 95, no. 11 (November 1, 2014): 2504–11. http://dx.doi.org/10.1099/vir.0.068221-0.
Full textAbstract:
We used SILAC (stable isotope labelling of amino acids in cell culture) and high-throughput quantitative MS mass spectrometry to analyse the protein composition of highly purified WT wild type adenoviruses, mutant adenoviruses lacking an internal protein component (protein V) and recombinant adenoviruses of the type commonly used in gene therapy, including one virus that had been used in a clinical trial. We found that the viral protein abundance and composition were consistent across all types of virus examined except for the virus lacking protein V, which also had reduced amounts of another viral core protein, protein VII. In all the samples analysed we found no evidence of consistent packaging or contamination with cellular proteins. We believe this technique is a powerful method to analyse the protein composition of this important gene therapy vector and genetically engineered or synthetic virus-like particles. The raw data have been deposited at proteomexchange, identifer PXD001120.
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Behrmann-Godel, J., and E. Yohannes. "Multiple isotope analyses of the pike tapeworm Triaenophorus nodulosus reveal peculiarities in consumer–diet discrimination patterns." Journal of Helminthology 89, no. 2 (January 22, 2014): 238–43. http://dx.doi.org/10.1017/s0022149x13000849.
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AbstractPrevious studies of dietary isotope discrimination have led to the general expectation that a consumer will exhibit enriched stable isotope levels relative to its diet. Parasite–host systems are specific consumer–diet pairs in which the consumer (parasite) feeds exclusively on one dietary source: host tissue. However, the small numbers of studies previously carried out on isotopic discrimination in parasite–host (ΔXP-HT) systems have yielded controversial results, showing some parasites to be isotopically depleted relative to their food source, while others are enriched or in equilibrium with their hosts. Although the mechanism for these deviations from expectations remains to be understood, possible influences of specific feeding niche or selection for only a few nutritional components by the parasite are discussed. ΔXP-HT for multiple isotopes (δ13C, δ15N, δ34S) were measured in the pike tapeworm Triaenophorus nodulosus and two of its life-cycle fish hosts, perch Perca fluviatilis and pike Esox lucius, within which T. nodulosus occupies different feeding locations. Variability in the value of ΔXP-HT calculated for the parasite and its different hosts indicates an influence of feeding location on isotopic discrimination. In perch liver ΔXP-HT was relatively more negative for all three stable isotopes. In pike gut ΔXP-HT was more positive for δ13C, as expected in conventional consumer–diet systems. For parasites feeding on pike gut, however, the δ15N and δ34S isotope values were comparable with those of the host. We discuss potential causes of these deviations from expectations, including the effect of specific parasite feeding niches, and conclude that ΔXP-HT should be critically evaluated for trophic interactions between parasite and host before general patterns are assumed.
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Wagner, D. S., C. J. Markworth, C. D. Wagner, F. J. Schoenen, C. E. Rewerts, B. K. Kay, and H. M. Geysen. "Ratio encoding combinatorial libraries with stable isotopes and their utility in pharmaceutical research." Combinatorial Chemistry & High Throughput Screening 1, no. 3 (October 1998): 143–53. http://dx.doi.org/10.2174/138620730103220120142733.
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Combinatorial libraries are an important tool for lead discovery in the pharmaceutical industry. Advances in high throughput screening coupled with combinatorial chemistry can significantly reduce the time to find lead compounds. A major difficulty in developing large combinatorial libraries is the ability to identify active compounds. This paper describes a rapid and sensitive encoding/decoding methodology that utilizes stable isotopes and mass spectrometry. The ability of mass spectrometry to precisely determine the intensity of isotopic abundances provides a unique encoding strategy employing synthetically generated ratios of stable isotopes in a compound as the code. The application of ratio encoding is demonstrated using peptoid and imidazole chemistries. Supporting data demonstrate that the incorporation of one or more stable isotopes using unique-predetermined ratios can encode chemical libraries. In addition, the presence of a unique isotopic pattern in a ligand can facilitate the pharmacokinetic analysis. Isotope incorporation into a compound and subsequently into its metabolites reliably distinguishes products from other molecules in the mass spectrum. This is illustrated by metabolic analyses of peptoid and imidazole compounds.
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Horwath, Aline B., Jessica Royles, Richard Tito, José A. Gudiño, Noris Salazar Allen, William Farfan-Rios, Joshua M. Rapp, et al. "Bryophyte stable isotope composition, diversity and biomass define tropical montane cloud forest extent." Proceedings of the Royal Society B: Biological Sciences 286, no. 1895 (January 23, 2019): 20182284. http://dx.doi.org/10.1098/rspb.2018.2284.
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Liverworts and mosses are a major component of the epiphyte flora of tropical montane forest ecosystems. Canopy access was used to analyse the distribution and vertical stratification of bryophyte epiphytes within tree crowns at nine forest sites across a 3400 m elevational gradient in Peru, from the Amazonian basin to the high Andes. The stable isotope compositions of bryophyte organic material ( 13 C/ 12 C and 18 O/ 16 O) are associated with surface water diffusive limitations and, along with C/N content, provide a generic index for the extent of cloud immersion. From lowland to cloud forest δ 13 C increased from −33‰ to −27‰, while δ 18 O increased from 16.3‰ to 18.0‰. Epiphytic bryophyte and associated canopy soil biomass in the cloud immersion zone was estimated at up to 45 t dry mass ha −1 , and overall water holding capacity was equivalent to a 20 mm precipitation event. The study emphasizes the importance of diverse bryophyte communities in sequestering carbon in threatened habitats, with stable isotope analysis allowing future elevational shifts in the cloud base associated with changes in climate to be tracked.
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Ebert, Claire E., Asta J. Rand, Kirsten Green-Mink, Julie A. Hoggarth, Carolyn Freiwald, Jaime J. Awe, Willa R. Trask, et al. "Sulfur isotopes as a proxy for human diet and mobility from the preclassic through colonial periods in the Eastern Maya lowlands." PLOS ONE 16, no. 8 (August 12, 2021): e0254992. http://dx.doi.org/10.1371/journal.pone.0254992.
Full textAbstract:
Maya archaeologists have long been interested in understanding ancient diets because they provide information about broad-scale economic and societal transformations. Though paleodietary studies have primarily relied on stable carbon (δ13C) and nitrogen (δ15N) isotopic analyses of human bone collagen to document the types of food people consumed, stable sulfur (δ34S) isotope analysis can potentially provide valuable data to identify terrestrial, freshwater, or marine/coastal food sources, as well as determine human mobility and migration patterns. Here we assess applications of δ34S for investigating Maya diet and migration through stable isotope analyses of human bone collagen (δ13C, δ15N, and δ34S) from 114 individuals from 12 sites in the Eastern Maya lowlands, temporally spanning from the Late Preclassic (300 BCE—300 CE) through Colonial periods (1520–1800 CE). Results document a diet dominated by maize and other terrestrial resources, consistent with expectations for this inland region. Because δ34S values reflect local geology, our analyses also identified recent migrants to the Eastern lowlands who had non-local δ34S signatures. When combined with other indicators of mobility (e.g., strontium isotopes), sulfur isotopic data provide a powerful tool to investigate movement across a person’s lifespan. This study represents the largest examination of archaeological human δ34S isotope values for the Maya lowlands and provides a foundation for novel insights into both subsistence practices and migration.
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Böhlke, J. K. "Variation in the terrestrial isotopic composition and atomic weight of argon (IUPAC Technical Report)." Pure and Applied Chemistry 86, no. 9 (September 19, 2014): 1421–32. http://dx.doi.org/10.1515/pac-2013-0918.
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AbstractThe isotopic composition and atomic weight of argon (Ar) are variable in terrestrial materials. Those variations are a source of uncertainty in the assignment of standard properties for Ar, but they provide useful information in many areas of science. Variations in the stable isotopic composition and atomic weight of Ar are caused by several different processes, including (1) isotope production from other elements by radioactive decay (radiogenic isotopes) or other nuclear transformations (e.g., nucleogenic isotopes), and (2) isotopic fractionation by physical-chemical processes such as diffusion or phase equilibria. Physical-chemical processes cause correlated mass-dependent variations in the Ar isotope-amount ratios (40Ar/36Ar, 38Ar/36Ar), whereas nuclear transformation processes cause non-mass-dependent variations. While atmospheric Ar can serve as an abundant and homogeneous isotopic reference, deviations from the atmospheric isotopic ratios in other Ar occurrences limit the precision with which a standard atomic weight can be given for Ar. Published data indicate variation of Ar atomic weights in normal terrestrial materials between about 39.7931 and 39.9624. The upper bound of this interval is given by the atomic mass of 40Ar, as some samples contain almost pure radiogenic 40Ar. The lower bound is derived from analyses of pitchblende (uranium mineral) containing large amounts of nucleogenic 36Ar and 38Ar. Within this interval, measurements of different isotope ratios (40Ar/36Ar or 38Ar/36Ar) at various levels of precision are widely used for studies in geochronology, water–rock interaction, atmospheric evolution, and other fields.
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Gagnon, Chantal, and Keith A. Hobson. "Using stable isotopes to track frugivory in migratory passerines." Canadian Journal of Zoology 87, no. 11 (November 2009): 981–92. http://dx.doi.org/10.1139/z09-086.
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Several species of North American migratory songbirds undergo seasonal diet shifts from insects to fruits, but this phenomenon is poorly quantified. Measurement of naturally occurring stable isotopes of carbon (δ13C) and nitrogen (δ15N) are linked to sources of diets and trophic level, respectively. We used stable carbon (δ13C) and nitrogen (δ15N) isotope analyses of blood and claw tissues of 16 species of migratory songbirds to evaluate the timing and extent of frugivory over different periods. Species differed considerably in their tissue δ15N values, but we found poor isotopic segregation of species according to our a priori classifications as insectivores or omnivores. Season accounted for considerable variance in tissue δ15N values. However, only American Robin ( Turdus migratorius L., 1766), Northern Oriole ( Icterus galbula (L., 1758)), Gray Catbird ( Dumetella carolinensis (L., 1766)), Least Flycatcher ( Empidonax minimus (W.M. Baird and S.F. Baird, 1843)), and Warbling Vireo ( Vireo gilvus (Vieillot, 1808)) showed expected decrease in winter-grown tissue δ15N values compared with those grown in late summer. This indicates either that our a priori guild associations were incorrect and (or) that using stable isotopes to track frugivory at continental scales is problematic. We recommend that the isotope technique be used to track frugivory only in well-constrained systems where food-web δ15N follows reliable and understood trophic enrichment patterns.
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Cullen, T. M., F. J. Longstaffe, U. G. Wortmann, M. B. Goodwin, L. Huang, and D. C. Evans. "Stable isotopic characterization of a coastal floodplain forest community: a case study for isotopic reconstruction of Mesozoic vertebrate assemblages." Royal Society Open Science 6, no. 2 (February 2019): 181210. http://dx.doi.org/10.1098/rsos.181210.
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Stable isotopes are powerful tools for elucidating ecological trends in extant vertebrate communities, though their application to Mesozoic ecosystems is complicated by a lack of extant isotope data from comparable environments/ecosystems (e.g. coastal floodplain forest environments, lacking significant C 4 plant components). We sampled 20 taxa across a broad phylogenetic, body size, and physiological scope from the Atchafalaya River Basin of Louisiana as an environmental analogue to the Late Cretaceous coastal floodplains of North America. Samples were analysed for stable carbon, oxygen and nitrogen isotope compositions from bioapatite and keratin tissues to test the degree of ecological resolution that can be determined in a system with similar environmental conditions, and using similar constraints, as those in many Mesozoic assemblages. Isotopic results suggest a broad overlap in resource use among taxa and considerable terrestrial–aquatic interchange, highlighting the challenges of ecological interpretation in C 3 systems, particularly when lacking observational data for comparison. We also propose a modified oxygen isotope-temperature equation that uses mean endotherm and mean ectotherm isotope data to more precisely predict temperature when compared with measured Atchafalaya River water data. These results provide a critical isotopic baseline for coastal floodplain forests, and act as a framework for future studies of Mesozoic palaeoecology.
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Kelleway, J. J., S. M. Trevathan-Tackett, J. Baldock, and L. P. Critchley. "Plant litter composition and stable isotope signatures vary during decomposition in blue carbon ecosystems." Biogeochemistry 158, no. 2 (February 1, 2022): 147–65. http://dx.doi.org/10.1007/s10533-022-00890-3.
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AbstractThe ratio of isotopes of carbon (13C:12C or δ13C) and nitrogen (15N:14N or δ15N) are common indicators of the flow and storage of organic matter in coastal wetland research. Effective use of these indicators requires quantification and understanding of: (1) the variability of isotope signatures of potential organic matter source materials; and (2) the influence of organic matter decomposition on isotopic signatures. While it is well-established that organic matter characteristics change during the decomposition process, there has been little direct quantification of any concurrent shifts in isotope signatures for coastal detritus. In this study, we addressed this by quantifying: (1) shifts in sample composition using solid-state 13C Nuclear Magnetic Resonance (NMR) spectroscopy; and (2) shifts in δ13C and δ15N signatures of coastal plant tissues from field litterbag experiments. We observed significant shifts in 13C NMR spectra across the course of deployment for all four plant tissues assessed (leaves of mangrove Avicennia marina; branchlets of supratidal tree Casuarina glauca; leaf wrack and roots/rhizomes of the seagrass Zostera muelleri), driven largely by the preferential loss of labile constituents and concentration of more resistant macromolecules, such as lignin and leaf waxes. While there were shifts in isotope ratios for all species, these varied in direction and magnitude among species, tissue type and isotopes. This included δ13C enrichments of up to 3.1‰ and 2.4‰ in leaves of A. marina, and branchlets of C. glauca, respectively, but δ13C depletions of up to 4.0‰ for Z. muelleri. Shifts in δ15N varied among species and tissue types, with few clear temporal patterns. Partial least squares regression analyses showed that some tissue isotope signatures can be reliably predicted on the basis of sample composition (13C NMR spectra), however, multiple inter- and intra-species variations preclude a simple explanation of isotopic signature shifts on the basis of plant-material molecular shifts alone. Further, we cannot preclude the potential influence of microbe-associated organic matter on sample composition or isotopic signatures. Our findings emphasise the importance of considering decomposition effects on stable isotope signatures in blue carbon ecosystems. Isotope approaches will remain a valuable tool in coastal ecosystem research, but require robust experimental approaches (including appropriate use of decomposed end-members or fractionation correction factors; quantification of microbial organic matter) and quantification of decomposition dynamics for specific plant tissues and environmental settings.
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C. Banda, Limbikani, Michael Rivett, Robert Kalin, Anold Zavison, Peaches Phiri, Geoffrey Chavula, Charles Kapachika, Sydney Kamtukule, Christina Fraser, and Muthi Nhlema. "Seasonally Variant Stable Isotope Baseline Characterisation of Malawi’s Shire River Basin to Support Integrated Water Resources Management." Water 12, no. 5 (May 15, 2020): 1410. http://dx.doi.org/10.3390/w12051410.
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Integrated Water Resources Management (IWRM) is vital to the future of Malawi and motivates this study’s provision of the first stable isotope baseline characterization of the Shire River Basin (SRB). The SRB drains much of Southern Malawi and receives the sole outflow of Lake Malawi whose catchment extends over much of Central and Northern Malawi (and Tanzania and Mozambique). Stable isotope (283) and hydrochemical (150) samples were collected in 2017–2018 and analysed at Malawi’s recently commissioned National Isotopes Laboratory. Distinct surface water dry-season isotope enrichment and wet-season depletion are shown with minor retention of enriched signatures ascribed to Lake Malawi influences. Isotopic signatures corroborate that wet-season river flows mostly arise from local precipitation, with dry-season flows supported by increased groundwater contributions. Groundwater signatures follow a local meteoric water line of limited spread suggesting recharge by local precipitation predominantly during the peak months of the wet-season. Relatively few dry-season groundwater samples displayed evaporative enrichment, although isotopic seasonality was more pronounced in the lowlands compared to uplands ascribed to amplified climatic effects. These signatures serve as isotopic diagnostic tools that valuably informed a basin conceptual model build and, going forward, may inform key identified Malawian IWRM concerns. The isotopic baseline establishes a benchmark against which future influences from land use, climate change and water mixing often inherent to IWRM schemes may be forensically assessed. It thereby enables both source-water protection and achievement of Sustainable Development Goal 6.
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Borić, Dušan, Gisela Grupe, Joris Peters, and Živko Mikić. "Is the Mesolithic–Neolithic Subsistence Dichotomy Real? New Stable Isotope Evidence from the Danube Gorges." European Journal of Archaeology 7, no. 3 (December 2004): 221–48. http://dx.doi.org/10.1177/1461957104056500.
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The article presents new results of stable isotope analyses made on animal and human bones from the Mesolithic–early Neolithic sites of Lepenski Vir and Vlasac in the Danube Gorges of the Balkans. It reconstructs the food web for the region during these periods on the basis of stable isotope analyses of mammal and fish species found at Vlasac. These results are compared to measurements made on human burials from the two sites. In the light of these new results, the article also discusses interpretations provided by previous isotopic studies of this material. It concludes that great care is required in the interpretation of stable isotope results due to inherent methodological complexities of this type of analysis, and suggests that it is also necessary to integrate stable isotope results with information based on the examination of faunal remains and the archaeological context of analysed burials when making inferences about palaeodietary patterns.
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Guo, Rong, Shengjie Wang, Mingjun Zhang, Athanassios A. Argiriou, Xuemei Liu, Bo Su, Xue Qiu, et al. "Stable Hydrogen and Oxygen Isotope Characteristics of Bottled Water in China: A Consideration of Water Source." Water 11, no. 5 (May 22, 2019): 1065. http://dx.doi.org/10.3390/w11051065.
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The origin of bottled water can be identified via its stable isotope signature because of the spatial variation of the stable isotope composition of natural waters. In this paper, the spatial pattern of δ2H and δ18O values were analyzed for a total of 242 bottled water samples produced at 137 sites across China that were randomly purchased during 2014–2015. The isotopic ratios of bottled water vary between −166‰ and −19‰ for δ2H, and between −21.6‰ and −2.1‰ for δ18O. Based on multiple regression analyses using meteorological and geographical parameters, an isoscape of Chinese bottled water was created. The results showed that altitude among spatial parameters and precipitation amount and air temperature among meteorological parameters were major natural factors determining the isotopic variation of bottled water. Our findings indicate the potential and the significance of the use of stable isotopes for the source identification of bottled water. An analysis of different origin types (spring, glacier and unmarked) and several different brands of bottled water in the same location reflected different production processes and source signatures.
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Hobson, Keith A., Robert B. Brua, William L. Hohman, and Len I. Wassenaar. "Low Frequency of “Double Molt” of Remiges in Ruddy Ducks Revealed by Stable Isotopes: Implications for Tracking Migratory Waterfowl." Auk 117, no. 1 (January 1, 2000): 129–35. http://dx.doi.org/10.1093/auk/117.1.129.
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Abstract Ratios of the stable carbon (δ13C) and hydrogen (δD) isotopes in newly grown remiges of Ruddy Ducks (Oxyura jamaicensis) are influenced by the isotopic character of food types and ambient water. Systematic isotopic foodweb and water differences between coastal wintering grounds and prairie breeding grounds of Ruddy Ducks provide the basis for using isotopic analyses of feathers to trace the location and timing of molt. Anecdotal evidence, based largely on captive birds, suggests that Ruddy Ducks replace their remiges twice each year (once each on the breeding and wintering grounds), but a recent literature analysis indicates that this phenomenon is rare. Thus, we investigated the extent to which a biannual molt of the remiges occurs in the wild and at the population level. We analyzed the stable isotopes of carbon (n = 57 birds) and hydrogen (n = 50 birds) in flight feathers to estimate the prevalence of the so-called “double molt” of remiges in free-living Ruddy Ducks. Our data showed that natural populations of Ruddy Ducks express an overwhelming unimodal distribution of isotope ratios in their remiges, suggesting that they undergo a single molt at or near the breeding grounds. Only 3 to 6 of 50 birds from Manitoba showed isotopic evidence consistent with growing remiges on the wintering grounds. Feathers from Ruddy Ducks harvested during the fall in the Mississippi Flyway had isotopic profiles consistent with growth on northern freshwater breeding sites. Thus, our results confirm that the replacement of remiges twice each year by Ruddy Ducks is rare, and they suggest that this dual stable-isotope technique can be used to infer general molting origins of North American waterfowl.
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Ruiz-Cooley, R. I., Unai Markaida, D. Gendron, and S. Aguíñiga. "Stable isotopes in jumbo squid (Dosidicus gigas) beaks to estimate its trophic position: comparison between stomach contents and stable isotopes." Journal of the Marine Biological Association of the United Kingdom 86, no. 2 (March 13, 2006): 437–45. http://dx.doi.org/10.1017/s0025315406013324.
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Stomach contents and carbon (C) and nitrogen (N) stable isotope analysis were used to evaluate trophic relationships of jumbo squid, Dosidicus gigas. Buccal masses, beaks and stomach contents of large and medium maturing-sized jumbo squid and muscle from its main prey, the myctophid Benthosema panamense, were collected in the Gulf of California, Mexico during 1996, 1997 and 1999. Both the quantified C and N-isotope ratios in muscle, and stomach content analysis revealed that larger-sized maturing squid showed a higher trophic position than medium-sized individuals. However, a discrepancy between stomach contents versus stable isotope analyses was found in evaluating trophic relationships. Simple dilution models as a function of growth were used to estimate the C and N renewal dietary shift for jumbo squid. Estimates of the initial C and N pools in D. gigas with an initial age of 70 days and 210 days indicated isotopic shifts of 32% after a threefold biomass increase and 25% after a fourfold biomass increase, respectively. Additionally, beak samples of jumbo squid were evaluated as an alternative tissue to estimate squid trophic position using stable isotopes. The results showed a significant correlation between stable isotope ratios from muscle and beak samples. Muscle isotope values were higher than beak by 1% and 4% for δ13C and δ15N respectively. A test with jumbo squid beaks collected from a stomach of a stranded sperm whale confirmed the viability of this method.
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Winterová, R., R. Mikulíková, J. Mazáč, and P. Havelec. "Assessment of the authenticity of fruit spirits by gas chromatography and stable isotope ratio analyses." Czech Journal of Food Sciences 26, No. 5 (October 31, 2008): 368–75. http://dx.doi.org/10.17221/1610-cjfs.
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The gas chromatographic (GC) determination of volatile constituents and the determination of <sup>13</sup>C/<sup>12</sup>C isotope ratios by isotope ratio mass spectrometry – IRMS analysis as well as SNIF–NMR analysis of (D/H)I and (D/H)II ratios in ethanol are prospective analytical methods which can be used for checking the authenticity of fruit spirits and for detecting their adulteration. Different concentrations of volatile compounds such as acetaldehyde, ethyl acetate, diethyl acetal, methanol, 1-butanol, 2-butanol, 1-propanol, 2-methyl-1-propanol, 2- and 3-methyl-1-butanol, volatile fatty acids and isotopic data were demonstrated using discriminant analysis. The results show that the determination of isotope ratios can be used especially for distinguishing between fruit spirits and others spirits, i.e. those made from beet sugar, maize, cane sugar, grain, potato, or synthetic alcohol. Gas chromatography also makes it possible to discriminate between respective spirits derived from one kind of fruit such as sweet cherry brandy, sour cherry brandy, pear brandy, apple brandy, apricot brandy, or plum brandy.
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Mance, Diana, Maja Radišić, Danijela Lenac, and Josip Rubinić. "Hydrological Behavior of Karst Systems Identified by Statistical Analyses of Stable Isotope Monitoring Results." Hydrology 9, no. 5 (May 11, 2022): 82. http://dx.doi.org/10.3390/hydrology9050082.
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The article presents findings of a two-year systematic study of stable isotope content in two karst groundwater resources in Primorsko-goranska county (Croatia): the Martinšćica wells (MWs) and the Dobrica spring (DBC). The temporal and spatial variation of hydrogen and oxygen isotopes is commonly studied in conjunction with hydrogeological conditions such as groundwater dynamics and discharge conditions. However, since this information was incomplete, we were forced to work with limited data and rely on analyses of stable isotope monitoring results. The obtained results show that winter precipitation is the most common recharge source for the systems, and the average residence time of water in the subsurface is less than a year. Furthermore, the MWs system is a typical dual-porosity system with dominant base flow. The results of the nonparametric regression analysis show that the possibility of seawater intrusion into the spring affecting DBC isotope content cannot be ruled out. We believe that the results presented in the paper demonstrate that when combined with statistical analyses, environmental stable isotopes are a powerful tool for gaining insights in karst hydrogeology.
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Day, M., Ben Li Zhang, Gérard J. Martin, Christian Asselin, and René Morlat. "Characterization of the region and year of production of wines by stable isotopes and elemental analyses." OENO One 29, no. 2 (June 30, 1995): 75. http://dx.doi.org/10.20870/oeno-one.1995.29.2.1129.
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<p style="text-align: justify;">Stable isotope and elemental analyses were applied to the study of wines produced from the Cabernet Franc vine variety cultivated during several years (1982 to 1990) on specific parts of the Saumur-Champigny vineyard dedicated to the « terroir » experiment of INRA. The purpose of this work was to describe the behaviour or <sup>2</sup>H, <sup>13</sup>C and <sup>18</sup>O isotopes in the water and ethanol of wines in terms of the meteorological conditions (temperature, precipitation and insolation) which govern vine growing. Since the « terroir » concept involves a synergy between the c1imate and the soil, the distribution of typical metallic elements was also determined by flame and electrothermal ionization atomic absorption. About twenty parcels, carefully described from the geological and pedological point of view were considered in this study which demonstrated the ability of Sr, Al and Rb to discriminate between wines from the same year but grown on adjacent parcels. The content in trace elements of the wines was also shown to be correlated with the geological nature of the soil. As far as stable isotopes are considered, it appears that the climate of the year of production of a given region has a drastic influence on the isotope ratios of water and ethanol of wines and good correlations way be computed between these parameters and temperature and precipitations. From a more basic aspect, it is also shown that the nature of the soil which governs, at least in a part, the water use efficiency of vine, induces typical variations in the isotopic composition of wines. The results of this study demonstrate also the ability of stable isotope and elemental analyses to determine the geographical origin of a wine, and when the region of production is known, to infer the year of production from meteorological data. This method might prove to be an alternative method to radio carbon analysis for the next vintages.</p>
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Wackerbarth, A., P. M. Langebroek, M. Werner, G. Lohmann, S. Riechelmann, A. Borsato, and A. Mangini. "Simulated oxygen isotopes in cave drip water and speleothem calcite in European caves." Climate of the Past 8, no. 6 (November 5, 2012): 1781–99. http://dx.doi.org/10.5194/cp-8-1781-2012.
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Abstract. Interpreting stable oxygen isotope (δ18O) records from stalagmites is still one of the complex tasks in speleothem research. Here, we present a novel model-based approach, where we force a model describing the processes and modifications of δ18O from rain water to speleothem calcite (Oxygen isotope Drip water and Stalagmite Model – ODSM) with the results of a state-of-the-art atmospheric general circulation model enhanced by explicit isotope diagnostics (ECHAM5-wiso). The approach is neither climate nor cave-specific and allows an integrated assessment of the influence of different varying climate variables, e.g. temperature and precipitation amount, on the isotopic composition of drip water and speleothem calcite. First, we apply and evaluate this new approach under present-day climate conditions using observational data from seven caves from different geographical regions in Europe. Each of these caves provides measured δ18O values of drip water and speleothem calcite to which we compare our simulated isotope values. For six of the seven caves modeled δ18O values of drip water and speleothem calcite are in good agreement with observed values. The mismatch of the remaining caves might be caused by the complexity of the cave system, beyond the parameterizations included in our cave model. We then examine the response of the cave system to mid-Holocene (6000 yr before present, 6 ka) climate conditions by forcing the ODSM with ECHAM5-wiso results from 6 ka simulations. For a set of twelve European caves, we compare the modeled mid-Holocene-to-modern difference in speleothem calcite δ18O to available measurements. We show that the general European changes are simulated well. However, local discrepancies are found, and might be explained either by a too low model resolution, complex local soil-atmosphere interactions affecting evapotranspiration or by cave specific factors such as non-equilibrium fractionation processes. The mid-Holocene experiment pronounces the potential of the presented approach to analyse δ18O variations on a spatially large (regional to global) scale. Modelled as well as measured European δ18O values of stalagmite samples suggest the presence of a strong, positive mode of the North Atlantic Oscillation at 6 ka before present, which is supported by the respective modelled climate parameters.
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MINAMI, Hirotsugu. "Stable Isotope Analyses." Analytical Sciences 35, no. 6 (June 10, 2019): 607–8. http://dx.doi.org/10.2116/analsci.highlights1906.
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Eerkens, Jelmer W., Eric J. Bartelink, Laura Brink, Richard T. Fitzgerald, Ramona Garibay, Gina A. Jorgenson, and Randy S. Wiberg. "Trophy Heads or Ancestor Veneration? A Stable Isotope Perspective on Disassociated and Modified Crania in Precontact Central California." American Antiquity 81, no. 1 (January 2016): 114–31. http://dx.doi.org/10.7183/0002-7316.81.1.114.
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AbstractFew items in the archaeological record capture the imagination more than human heads separated from their bodies. Such items are sometimes assumed to indicate warfare practices, where “trophy heads” display power and fighting prowess. Other times, they are interpreted as representing ancestor veneration. Isolated crania are not uncommon in the Early period (ca. 4500–2500 B.P.) in Central California. Some anthropologists interpret them as trophy heads, but isotopie analyses at CA-CCO-548 suggest an alternative interpretation. Strontium isotope analyses on one modified cranium produced values consistent with local individuals, and both headless burials and people buried with extra skulls overlap in carbon and nitrogen isotopes. Further, teeth from two individuals who were buried with extra skulls suggest both were weaned at early ages (before age 2), much earlier than other individuals at the site. Together with contextual information, we argue that the isotopie data are more consistent with the hypothesis that extra skulls and headless burials represent ancestor veneration rather than trophies, shedding new light on Early-period societies in Central California.
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Banda, Limbikani C., Michael O. Rivett, Robert M. Kalin, Anold S. K. Zavison, Peaches Phiri, Laura Kelly, Geoffrey Chavula, et al. "Water–Isotope Capacity Building and Demonstration in a Developing World Context: Isotopic Baseline and Conceptualization of a Lake Malawi Catchment." Water 11, no. 12 (December 10, 2019): 2600. http://dx.doi.org/10.3390/w11122600.
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Developing countries such as Malawi require improved access to isotope tracer tools to better characterize and manage water resources threatened by land development, deforestation and climate change. This is the first published study to use an isotope facility developed in Malawi for this purpose, instead of relying upon sample analyses from abroad. Results from this new facility are used to evaluate an important Lake Malawi catchment in the Rift Valley. This work successfully established a stable-isotope baseline, hydrochemical signatures, and system conceptualization against which future policy change and management strategies may be measured. Precipitation isotopic composition was consistent with the Global Meteoric Water Line, but varied, confirming different precipitation systems nationally. Groundwater largely followed a Local Meteoric Water Line, with limited isotopic variation indicating predominant areal groundwater recharge, but with dry-season evaporative enrichment of groundwater near Lake Malawi. Surface-water isotopes widely varied with local precipitation, suggesting the latter accounted for wet-season river flows, but upstream dambo (complex wetlands occupying a shallow, seasonal waterlogged depression) helped sustain dry-season flows. Isotope capacity reinforced water-resource conceptualization and provenance in a hydrologically complex, but not atypical, Rift Valley system, exhibiting a noted complexity of groundwater–surface-water interactions. The latter, critical to integrated water resource management, requires more focused study, to which an expanded array of isotopes will contribute to tracking Sustainable Development Goal 6 targets. This study and future catchment studies should help underpin Malawian water-resource policy implementation on several identified fronts.
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Hoogakker, B. A. A., R. S. Smith, J. S. Singarayer, R. Marchant, I. C. Prentice, J. R. M. Allen, R. S. Anderson, et al. "Terrestrial biosphere changes over the last 120 kyr." Climate of the Past 12, no. 1 (January 18, 2016): 51–73. http://dx.doi.org/10.5194/cp-12-51-2016.
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Abstract. A new global synthesis and biomization of long (> 40 kyr) pollen-data records is presented and used with simulations from the HadCM3 and FAMOUS climate models and the BIOME4 vegetation model to analyse the dynamics of the global terrestrial biosphere and carbon storage over the last glacial–interglacial cycle. Simulated biome distributions using BIOME4 driven by HadCM3 and FAMOUS at the global scale over time generally agree well with those inferred from pollen data. Global average areas of grassland and dry shrubland, desert, and tundra biomes show large-scale increases during the Last Glacial Maximum, between ca. 64 and 74 ka BP and cool substages of Marine Isotope Stage 5, at the expense of the tropical forest, warm-temperate forest, and temperate forest biomes. These changes are reflected in BIOME4 simulations of global net primary productivity, showing good agreement between the two models. Such changes are likely to affect terrestrial carbon storage, which in turn influences the stable carbon isotopic composition of seawater as terrestrial carbon is depleted in 13C.
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Hita, Luis González, Miguel Angel Mejía-González, Blanca Carteño Martinez, Juan Carlos Aparicio-González, and Dustin Mañón Flores. "Isotopic composition of rainfall in Baja California Sur, México." International Journal of Hydrology 5, no. 3 (June 1, 2021): 93–100. http://dx.doi.org/10.15406/ijh.2021.05.00271.
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The study of the connection between precipitation and groundwater recharge/discharge using stable isotopes has been limited in México. One of the main limitations is the lack of local stable isotopes monitoring for rainfall. Indeed, only two stations of the Global Network of Isotopes in Precipitation operated in Mexico from 1962 to 1988. This study reports temporal characterization of stable isotopes in meteoric waters in the northwest of Mexico that has been lacking up to the present. Stable isotope analyses of the rain collected in the city of Loreto, state of Baja California Sur, from 2018 to 2021 were conducted using laser water isotope analyzers Picarro L2110-i and Los Gatos Research LWIA-45EP. A least squares regression of the isotope data was used to obtain the local meteoric water line: δ2H =8 δ18O + 9.4 (r2=0.98). The average value of winter rain is δ18O=-2.46 ‰ and δ2H=-10.2 ‰, monsoon rain δ18O=-4.93 ‰ y δ2H=-30.3 ‰, atmospheric river rain δ18O=-5.35 ‰ and δ2H=-33.3 ‰ and tropical cyclones rain δ18O= -10.7 ‰ y δ2H=-76.3. Isotope data indicated that tropical cyclones are the main source of recharge for the coastal aquifers of Baja California, Sur.
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Gennett, Judith A., and Ethan L. Grossman. "Oxygen and Carbon Isotope Trends in a Late Glacial-Holocene Pollen Site in Wyoming, U.S.A." Géographie physique et Quaternaire 40, no. 2 (December 4, 2007): 161–69. http://dx.doi.org/10.7202/032636ar.
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ABSTRACT Stable isotope studies of North American Late Glacial and Holocene lake sediments are few. Previous studies of pollen sites in Indiana, South Dakota, and the Great Lakes area show low δ18O values during deglaciation, rising to a Hypsithermal peak, and provide paleoenvironmental reconstructions similar to those obtained from pollen studies. Blacktail Pond, located in Douglas fir steppe in northern Yellowstone National Park, Wyoming, is one of the highest elevation lakes (2018 m) yet studied with both pollen and stable isotopes. Analyses of marls yield low oxygen and carbon isotope values at the base of the core probably due to meltwater influx at 12,500 to 14,000 BP. Tundra vegetation persisted for about an additional 1,500 years following the end of meltwater input. Later, more enriched isotope values fluctuate due to the high sensitivity of Blacktail Pond to evaporation and CO2 exchange because of its shallow depth. These processes result in a covariance between δ13C and δ18O related to the residence time of water in the pond; they exert a primary control on the isotopic composition of the Holocene marl. It may be possible to filter the data for residence time effects and extract additional paleoenvironmental information based on the offsets of isotopic data from the δ13C-δ18O trend for a particular pollen zone.
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Taylor, Matthew D., and Debashish Mazumder. "Stable isotopes reveal post-release trophodynamic and ontogenetic changes in a released finfish, mulloway (Argyrosomus japonicus)." Marine and Freshwater Research 61, no. 3 (2010): 302. http://dx.doi.org/10.1071/mf09014.
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Carbon and nitrogen stable isotope ratios were analysed for hatchery-reared, recaptured and wild mulloway, Argyrosomus japonicus, to investigate temporal and growth-related changes in isotopic composition for stocked fish after release, and to evaluate changes in isotopic composition in terms of ontogenetic dietary switches. δ13C and δ15N values decreased and increased, respectively, after release. The isotope composition of released fish was distinct from wild fish until 200 days after release, but after 200 days post-release fish did not differ significantly from wild fish of similar or greater sizes. Abrupt dietary transitions from crustaceans to teleost fish (>50 cm total length (TL)) were evident in a rapid δ13C and δ15N change in wild mulloway, and δ15N was significantly greater in wild fish >65 cm TL compared with wild fish <50 cm TL. Multivariate carbon and nitrogen isotopic data were suitable for separating stocked and wild fish for up to 200 days after release, but did not separate wild fish grouped according to dietary composition. Carbon and nitrogen isotopic composition closely reflected dietary transitions and rapid adaptation by stocked mulloway to wild diets, which was evident in a high tissue turnover rate of up to 0.017 day–1. Stable isotopes are a useful tool for examining the integration of released fish into stocked ecosystems and can be used to describe convergence in the diets of wild and released fish.
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Ala-aho, Pertti, Jeffrey M. Welker, Hannah Bailey, Stine Højlund Pedersen, Ben Kopec, Eric Klein, Moein Mellat, Kaisa-Riikka Mustonen, Kashif Noor, and Hannu Marttila. "Arctic Snow Isotope Hydrology: A Comparative Snow-Water Vapor Study." Atmosphere 12, no. 2 (January 25, 2021): 150. http://dx.doi.org/10.3390/atmos12020150.
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The Arctic’s winter water cycle is rapidly changing, with implications for snow moisture sources and transport processes. Stable isotope values (δ18O, δ2H, d-excess) of the Arctic snowpack have potential to provide proxy records of these processes, yet it is unclear how well the isotope values of individual snowfall events are preserved within snow profiles. Here, we present water isotope data from multiple taiga and tundra snow profiles sampled in Arctic Alaska and Finland, respectively, during winter 2018–2019. We compare the snowpack isotope stratigraphy with meteoric water isotopes (vapor and precipitation) during snowfall days, and combine our measurements with satellite observations and reanalysis data. Our analyses indicate that synoptic-scale atmospheric circulation and regional sea ice coverage are key drivers of the source, amount, and isotopic composition of Arctic snowpacks. We find that the western Arctic tundra snowpack profiles in Alaska preserved the isotope values for the most recent storm; however, post depositional processes modified the remaining isotope profiles. The overall seasonal evolution in the vapor isotope values were better preserved in taiga snow isotope profiles in the eastern Arctic, where there is significantly less wind-driven redistribution than in the open Alaskan tundra. We demonstrate the potential of the seasonal snowpack to provide a useful proxy for Arctic winter-time moisture sources and propose future analyses.