Search

The ratio of stable carbon isotopes can give important data about the sources of atmospheric carbon compounds. We consider a procedure for the determination of the isotopic composition of individual carbon fractions in atmospheric aerosols by isotope ratio mass spectrometry. We performed a preliminary analysis of carbon isotope composition ([delta].sup.13C) for various carbonaceous aerosol fractions (total carbon, organic + elemental carbon without carbonates, water-soluble organic carbon, water-insoluble carbon, and elemental carbon) collected during marine Arctic expeditions at the Ice base 'Cape Baranov', at the geophysical observatory of the Institute of Monitoring of Climatic and Ecological Systems of the Siberian Branch of the Russian Academy of Sciences (IMCES SB RAS) (Tomsk), and at the OPTIK Tu-134 aircraft laboratory., Author(s): D. A. Kalashnikova [sup.1] [sup.2] , G. V. Simonova [sup.1] , O. V. Lyamkina [sup.1] , A. O. Pochufarov [sup.2] Author Affiliations: (1) grid.494918.9, 0000 0004 0482 8585, Institute [...]

The results of analysis of the hydrogen, oxygen and carbon stable isotope ratios of honey samples taken in Russian regions with different climatic characteristics are presented. The values of isotope compositions in all studied honey samples vary from -29.5 to -24.2â° for carbon, from -116.6 to -34.5â° for hydrogen, and from +12.7 to +25.7â° for oxygen. It was shown that the values of the isotope compositions of carbon ([delta].sup.13С), hydrogen ([delta].sup.2Ð), and oxygen ([delta].sup.18Ð) in honey can be used to determine the geographical origin of honey. It was found that the average [delta].sup.2Ð and [delta].sup.18Ð values in honey to a large extent correlate with the average [delta].sup.2Ð and [delta].sup.18Ð values of atmospheric precipitation in the regions of honey origin. The isotope composition of carbon is affected by climate. Three zones of 'isotopic landscape' for the regions of Russia were identified: the lowest [delta].sup.13С, [delta].sup.2Ð, and [delta].sup.18Ð values are characteristic of Siberian honey samples, intermediate values corresponded to honey samples from the European part of Russia, and the highest values were recorded for honey samples from the Black Sea region., Author(s): D. A. Kalashnikova [sup.1] , G. V. Simonova [sup.1] Author Affiliations: (1) grid.494918.9, 0000 0004 0482 8585, Institute of Monitoring of Climatic and Ecological Systems, Siberian Branch, Russian Academy [...]

Knowledge of the diet ecology of apex predators in insular island ecosystems has direct applications to the conservation of endemic species at risk of extinction. We used stable isotopes of carbon and nitrogen to infer resource-use strategies of an indigenous predator, the Pacific marten (Martes caurina (Merriam, 1890)), in a highly modified ecosystem on Haida Gwaii, British Columbia, Canada. We used Bayesian isotopic mixing models to estimate the relative contributions of different food sources to marten diet across seasons and during overall lifetime, and to determine how diet varied with different levels of access to marine resources. Isotopes of carbon and nitrogen measured in hair and muscle tissue suggested that marten consumed salmon (3%-17%) and berries (25%-37%) seasonally; these diet groups were relatively minor components of the lifetime diet. Analysis of bone collagen suggested that terrestrial fauna--including birds, deer, small mammals, and invertebrates--contributed the most to diet (41%-55%), and marine invertebrates (38%-48%), not salmon (0%-3%), were the main allochthonous marine nutrient subsidy to lifetime diet. Plasticity in foraging ecology, combined with a broad dietary niche, introduced prey, notably the invasive Sitka black-tailed deer (Odocoileus hemionus sitkensis Merriam, 1898), as well as abundant marine resources, may allow marten to outcompete other indigenous and endemic carnivores on Haida Gwaii. Key words: Pacific marten, Martes caurina, Haida Gwaii, stable isotopes, diet ecology, mesocarnivore, apex predator, island ecosystem, species at risk. Les connaissances sur l'écologie alimentaire des prédateurs de niveau trophique supérieur dans les écosystèmes insulaires ont des applications directes pour la conservation d'espèces endémiques en danger de disparition. Nous utilisons des isotopes stables de carbone et d'azote pour inférer les stratégies d'utilisation des ressources d'un prédateur indigène, la marte du Pacifique (Martes caurina (Merriam, 1890)), dans un écosystème fortement modifié dans l'archipel Haida Gwaii (Colombie-Britannique, Canada). Nous utilisons des modèles de mélange isotopique bayésiens pour estimer les apports relatifs de différentes sources de nourriture au régime alimentaire des martes pour différentes saisons et sur toute la durée de vie, et pour déterminer les variations du régime alimentaire en fonction de différents degrés d'accès à des ressources marines. Les isotopes de carbone et d'azote mesurés dans les poils et les tissus musculaires indiqueraient que les martes consomment des saumons (3% - 17%) et des baies (25% - 37%) sur une base saisonnière; ces groupes alimentaires sont des composantes relativement mineures du régime alimentaire sur la durée de vie. L'analyse du collagène osseux donne à penser que la faune terrestre--dont des oiseaux, cerfs, petits mammifères et invertébrés--fait le plus grand apport au régime alimentaire des martes (41% - 55%), et que les invertébrés marins (38% - 48%), et non les saumons (0% - 3%), constituent le plus grand apport allochtone de nutriments marins à ce régime alimentaire sur toute la durée de vie. La plasticité de l'écologie de l'alimentation, combinée à une large niche alimentaire, des proies introduites, notamment le cerf de Sitka (Odocoileus hemionus sitkensis Merriam, 1898), une espèce envahissante, ainsi que d'abondantes ressources marines, pourraient permettre aux martes de prévaloir sur d'autres carnivores indigènes et endémiques dans l'archipel Haida Gwaii. [Traduit par la Rédaction] Mots-clés : marte du Pacifique, Martes caurina, archipel Haida Gwaii, isotopes stables, écologie alimentaire, mésocarnivore, prédateur de niveau trophique supérieur, écosystème insulaire, espèce en péril., Introduction The spread of invasive species through human activities has contributed to the majority of recent vertebrate extinctions and is one of the most significant threats to global biodiversity across [...]

Carbon isotope ratio (δ[sup.13]C) has been used as an indicator of water stress because plants discriminate less against [sup.13]C when under stress. The depth-to-water (DTW) topographic index provides an estimation of soil moisture based on topographic position and other characteristics of a site. To evaluate whether DTW and carbon isotope discrimination were related and to determine if these relationships are influenced by climate, we sampled three time periods, which differed in the amount of annual precipitation (MAP), from tree cores collected from 42 trembling aspen and 43 white spruce trees growing along DTW gradients at two locations in central Alberta, Canada. Increasing MAP led to lower δ[sup.13]C, indicating less drought stress as water availability increases, while δ[sup.13]C increased with DTW up to a threshold value, after which the relationship levelled off, suggesting that higher DTW values represent stress-inducing soil conditions. DTW and MAP were then combined into models (aspen, [R.sup.2] = 0.72; spruce, [R.sup.2] = 0.44) that could be used to delineate drought-prone areas during periods of low MAP. Tree height and diameter were also related to DTW, suggesting a functional relationship between an index capturing soil properties and tree size. Our results demonstrate the potential to use the DTW index as a measure of site conditions and to predict stand-level responses. Key words: depth-to-water topographic index, carbon isotope ratio, water stress, soil properties. Le rapport isotopique du carbone (δ[sup.13]C) a ete utilise comme indicateur de stress hydrique etant donne que les plantes exercent une moins forte discrimination du [sup.13]C lorsqu'elles sont stressees. L'indice topographique de profondeur de l'eau (DTW) fournit une estimation de l'humidite du sol fondee sur la position topographique et d'autres caracteristiques d'une station. Pour evaluer si DTW et la discrimination isotopique du C sont reliees et determiner si ces relations sont influencees par le climat, nous avons echantillonne trois periodes temporelles qui se distinguent par la quantite de precipitation annuelle (PA). L'echantillonnage a ete realise a l'aide de carottes prelevees sur 42 peupliers faux-trembles (Populus tremuloides Michx.) et 43 epinettes blanches (Picea glauca (Moench) Voss) croissant le long d'un gradient de DTW a deux endroits dans le centre de l'Alberta, au Canada. L'augmentation de PA entraine une baisse de δ[sup.13]C indicatrice d'une reduction du stress hydrique etant donne que la disponibilite de l'eau augmente, tandis que δ[sup.13]C augmente avec DTW jusqu'a une valeur seuil apres quoi la relation atteint un plateau indiquant que des valeurs plus elevees de DTW representent des conditions de sol qui induisent un stress. Les valeurs de DTW et PA ont ensuite ete combinees dans des modeles (peuplier faux-tremble [R.sup.2] = 0,72; epinette [R.sup.2] = 0,44) qui pourraient etre utilises pour delimiter les zones sujettes a la secheresse durant les periodes de faible PA. La hauteur et le diametre des arbres etaient aussi relies a PA indiquant qu'il existe une relation fonctionnelle entre un indice qui reflete les proprietes du sol et la taille des arbres. Nos resultats illustrent le potentiel d'utilisation de l'indice DTW comme mesure des conditions d'une station et pour predire les reactions a l'echelle du peuplement. [Traduit par la Redaction] Mots-cles : profondeur de l'eau, indice topographique, ratio isotopique du carbone, stress hydrique, proprietes du sol., Introduction Water stress in woody plants is recorded in the carbon isotope ratio of their leaves and wood. Discrimination against the heavier stable isotope of carbon (i.e., [sup.13]C) can occur [...]

A restudy of the palynology of the Whirlpool Formation and Power Glen Formation in New York (USA) yielded a diverse fossil assemblage with cryptospores, glomalean fungi, acritarchs, chitinozoans, scolecodonts, and [...]

The Wenlock-Ludlow series boundary (Silurian) has been recognized as a time of pronounced sea-level rise and the end of a globally recognized Late Homerian Stage (Mulde) positive carbon isotope excursion [...]

The [δ.sup.13][C.sub.carb] records from two geographically close sections of the shallow-water Kozel Limestone Member (late Wenlock Motol Formation; Perunica microplate) significantly differ in the magnitude of the Homerian carbon isotope [...]

One of the most serious problems in today Russia is the rise in crime associated with the illicit trafficking in narcotics and psychotropic substances. An increase in the amount of [...], The rise in crime associated with the illicit trafficking in narcotics and psychotropic substances is one of the most severe problems in Russia today. In recent years, cases of using seeds of poppy plant 'masked as food,' the bulk of which contains macroparticles of poppy straw visible to an unaided eye and which can be used as raw materials for the preparation of narcotic substances have become more frequent. In his work, using a Delta V Advantage isotopic mass spectrometer, we proposed criteria based on which tone can reveal artificial superinducements of poppy straw into 'food' poppy seeds or their absence. Keywords: poppy seeds, poppy straw, narcotics, isotope ratio mass spectrometry, carbon isotopes DOI: 10.1134/S1061934816050129

Sea ice algae can constitute an important carbon source for high-Antarctic euphausiids during winter. To quantify the importance of this 'sympagic carbon' during summer, the three most abundant Antarctic euphausiids, Euphausia superba, E. crystallorophias, and Thysanoessa macrura, collected off the Filchner Ice Shelf, were analyzed regarding their fatty acid (FA) and stable isotope compositions. Fingerprints of diatom- and dinoflagellate-associated FAs in the euphausiids indicated a mixed carbon source composition for all three species. Bulk and FA-specific carbon stable isotope compositions ([delta].sup.13C) were used to quantify the contribution of sympagic carbon versus phytoplankton-produced carbon to the euphausiids' carbon budget, suggesting a lower proportional contribution of sympagic carbon in E. superba (5-18%) compared to E. crystallorophias (16-36%) and T. macrura (15-36%). The latter two species probably received sympagic carbon through heterotrophic prey, a hitherto overlooked source of sympagic carbon for pelagic species. Euphausiids collected close to the surface indicated a higher importance of sympagic carbon to their carbon budget compared to individuals caught at greater depths. Our results imply that, in the southern Weddell Sea, ice algae play a significant, but possibly not critical role as a carbon source for the three euphausiids during summer. Their ability to utilize carbon of different origins implies a certain resilience to environmental change during summer. The winter period, however, remains the critical bottle neck of survival when Antarctic sea ice declines, because during this season of minimal pelagic productivity, ice algae standing stocks constitute the only dependable carbon source., Author(s): Doreen Kohlbach [sup.1] [sup.2] [sup.3] , Benjamin Allen Lange [sup.1] [sup.2] [sup.3] , Martin Graeve [sup.1] , Martina Vortkamp [sup.1] , Hauke Flores [sup.1] [sup.2] Author Affiliations: (Aff1) 0000 [...]

The Moose River Basin in Ontario, Canada, contains nearly 1 km of Silurian marine strata, and although it has been studied for more than a century, its precise correlation globally has not been constrained. Herein, a core from the Victor Mine in the Moose River Basin was examined for conodont biostratigraphy and carbonate carbon (δ[sup.13][C.sub.carb]) isotope chemostratigraphy to provide a detailed chronostratigraphic framework for the Silurian strata (Severn River, Ekwan River, and Attawapiskat formations) in the Moose River Basin. The recovery of Aspelundia expansa, Aspelundia fluegeli fluegeli, Distomodus staurognathoides, Ozarkodina polinclinata estonica, Pterospathodus eopennatus, and Aulacognathus bullatus, as well as the lower Aeronian, upper Aeronian, lower Telychian (Valgu), and ascending limb of the Sheinwoodian (Ireviken) positive carbonate carbon (δ[sup.13][C.sub.carb]) isotope excursions provide significantly improved chronostratigraphic correlation of Llandovery strata in the Moose River Basin. Le bassin de la riviere Moose (Ontario, Canada) renferme pres de 1 km de strates marines siluriennes et, bien qu'il ait ete etudie pendant plus d'un siecle, sa correlation planetaire precise n'a pas ete etablie. Une carotte de la mine Victor dans le bassin de la riviere Moose a ete examinee pour en determiner la biostratigraphie des conodontes et la chimiostratigraphie des isotopes du carbone (δ[sup.13][C.sub.carb]) dans les carbonates afin d'etablir un cadre chronostratigraphique detaille pour les strates siluriennes (Formations de la riviere Severn, de la riviere Ekwan et d'Attawapiskat), dans le bassin de la riviere Moose. La recuperation Aspelundia expansa, Aspelundia fluegeli fluegeli, Distomodus staurognathoides, Ozarkodina polinclinata estonica, Pterospathodus eopennatus et Aulacognathus bullatus, ainsi que les excursions positives des isotopes du carbone (δ[sup.13][C.sub.carb]) dans les carbonates de l'Aeronien inferieur, de l'Aeronien superieur, du Telychien inferieur (Valgu) et du membre ascendant du Sheinwoodien (Ireviken) ameliorent significativement la correlation chronostratigraphique des strates llandoveriennes du bassin de la riviere Moose. [Traduit par la Redaction], Introduction The Hudson Platform (central Canadian Shield, Fig. 1) was located in the tropical climate belt during the Silurian Period at low latitudes (between 0°S and 10°S) just south of [...]

Tight oil in the Permian Tiaohu Formation in the Santanghu Basin, northwest China, has a peculiar property such that the reservoir is sedimentary organic matter-bearing tuff characterized by high porosity (10%-25%) and very low permeability, mainly in the range of 0.01-0.50 mD. Biomarker and stable carbon isotope compositions of selected crude oils and source-rock extracts were analyzed to determine the source rock of the tight oil. Source rocks in the Lucaogou Formation consist of various rock types dominated by mudstones containing organic matter with intense yellow-green fluorescence. Mudstones in the Lucaogou Formation have total organic carbon (TOC) values mainly in the range of 1.0-8.0 wt%, hydrocarbon generation potential ([S.sub.1] + [S.sub.2]) mostly > 6 mg/g, and chloroform extractable bitumen 'A' generally > 0.1%. The maceral composition is predominantly fluorescing amorphinite. The hydrogen index (HI) varies from 300 to 900 mg HC/g TOC, indicating dominant Type I and Type II kerogen. Compared with the mudstones and tuffs in the Tiaohu Formation, the mudstones in the Lucaogou Formation are the best source rocks. The biomarker characteristics of mudstone extracts in the Lucaogou Formation differ from those in the Tiaohu Formation, based on the gammacerane index, β-carotane content, and the relative contents of [C.sub.27], [C.sub.28], and [C.sub.29] regular steranes. Crude oil samples in the tuff show low pristane/phytane (Pr/Ph) ratios, high gammacerane indices, high β-carotane, and a dominance of the [C.sub.29] regular sterane followed by [C.sub.28] and [C.sub.27] steranes, as well as depleted stable carbon isotope compositions. Oil-source correlation with biomarkers and δ[sup.13]C values shows that the crude oil in the tuffs mainly originates from underlying source rocks in the Lucaogou Formation. The sedimentary organic matter in the tuffs also makes a small contribution to the tuffaceous reservoir. Therefore, the tuffaceous tight reservoir in the Tiaohu Formation is unusual in that the oil is not indigenous; rather, it migrates a long distance to accumulate in the upper reservoir. Le petrole du reservoir etanche de la Formation de Tiaohu (Permien) dans le bassin de Santanghu, nord-ouest de la Chine, a une propriete particuliere : le reservoir est un tuf d'origine sedimentaire comportant de la matiere organique, il est caracterise par une porosite elevee (10-25 %) et une tres basse permeabilite, principalement de l'ordre de 0,01-0,50 mD. La composition des biomarqueurs et des isotopes stables du carbone de petroles bruts choisis et d'extraits de la roche mere a ete analysee afin de determiner la roche mere du petrole de reservoir etanche. Les roches meres de la Formation de Lucaogou comprennent divers types de roches dominees par des mudstones contenant de la matiere organique a fluorescence jaune- vert intense. Les mudstones de la Formation de Lucaogou ont une teneur en carbone organique total (COT) surtout de l'ordre de 1,0-8,0 % poids, un potentiel de generation d'hydrocarbures (S1 + S2) principalement > 6 mg/g et un bitume <>, qui peut etre extrait par le chloroforme, > 0,1 %. La composition macerale predominante est l'amorphinite fluorescent. L'indice d'hydrogene varie de 300 a 900 mg HC/g COT, indiquant un kerogene a dominance de type I et de type II. Par rapport aux mudstones et aux tufs de la Formation de Tiaohu, les mudstones de la Formation de Lucaogou sont de meilleures roches meres. Les caracteristiques des biomarqueurs des extraits de mudstones dans la Formation de Lucaogou sont differentes de celles des biomarqueurs de la Formation de Tiaohu, si l'on se base sur l'indice de gammacerane, la teneur en carotane-p et la teneur relative des steranes reguliers [C.sub.27], [C.sub.28] et [C.sub.29]. Les echantillons de petrole brut dans le tuf montrent de faibles rapports pristane/phytane, des indices eleves de gammacerane, une teneur elevee en carotane-p et une predominance du sterane regulier [C.sub.29], suivi des steranes [C.sub.28] et [C.sub.27] ainsi que des compositions appauvries en isotopes stables du carbone. La correlation entre le petrole et sa source, etablie par des biomarqueurs et des valeurs de δ[sup.13]C, montre que le petrole brut dans les tufs provient surtout des roches meres sous-jacentes dans la Formation de Lucaogou. La matiere organique sedimentaire dans les tufs contribue aussi un peu aux reservoirs tufaces. Ainsi, le reservoir etanche tuface de la Formation de Tiaohu est inhabituel en ce sens que le petrole n'est pas indigene, il a plutot migre sur une longue distance pour s'accumuler dans le reservoir superieur. [Traduit par la Redaction], Introduction Located in the northeastern Xinjiang Uygur Autonomous Region of China, the Santanghu Basin is adjacent to the Republic of Mongolia to the north, the Turpan-Hami Basin to the south, [...]

Stable isotope analysis is frequently applied as a tool to examine dietary patterns in animals. However, some of the underlying assumptions associated with using this approach are increasingly being questioned. We carried out a controlled diet experiment on the southern African spiny mouse (Acomys spinosissimus Peters, 1852) to test a number of aspects relating to these assumptions and also examine the hypothesis that stable isotopes, especially δ[sup.15]N, can be used to provide evidence of nutritional stress. We compared the δ[sup.13]C and δ[sup.15]N values of livers and blood from animals that were fed ad libitum with animals undergoing a 10% reduction in food supply. Food-restricted animals showed no significant difference in δ[sup.15]N; however, δ[sup.13]C values of both liver and blood were depleted. Restricted animals also had a significantly lower C:N ratio. We examined the role of lipids and found following lipid extraction that both livers and lipids still showed the same separation in carbon values. Tissue-diet discrimination values were also calculated and found to be higher for both Δ[sup.13]C and Δ[sup.15]N compared with other mice species. Empirical values for discrimination rates were then compared with values calculated using an alternative method based on employing generic values and were found to be dissimilar, suggesting the use of generic values are not always appropriate. Our results highlight the need for greater understanding of the assumptions associated with using stable isotope analysis to examine diet and we suggest that studying a single species under captive conditions presents an ideal method to begin to test these hypotheses. Key words: Acomys spinosissimus, discrimination, food restriction, spiny mouse, stable isotope. Resume: L'analyse des isotopes stables est frequemment employee comme outil pour examiner les habitudes alimentaires d'animaux. Certaines des hypotheses qui sous-tendent cette approche sont toutefois de plus en plus remises en question. Nous avons mene une experience d'alimentation controlee sur la souris epineuse d'Afrique meridionale (Acomys spinosissimus Peters, 1852), afin de verifier differents aspects associes a ces hypotheses et d'examiner l'hypothese voulant que les isotopes stables, en particulier les valeurs de δ[sup.15]N, puissent etre utilises pour fournir des indices de stress nutritif. Nous avons compare des valeurs de δ[sup.13]C et δ[sup.15]N du foie et du sang d'individus nourris fi volonte a celles d'animaux assujettis aune reduction de 10 % de leur approvisionnement. Les animaux dont l'approvisionnement etait restreint ne presentaient aucune difference significative du δ[sup.15]N; cependant, les valeurs de δ[sup.13]N tant pour le foie que pour le sang etaient appauvries. Les animaux restreints presentaient egalement un rapport C:N significativement plus faible. Nous avons examine le role des lipides et constate que, apres extraction de ces derniers, les foies et les lipides presentaient toujours la meme separation de leurs valeurs de carbone. Des valeurs de discrimination tissusregime ont egalement ete calculees et etaient plus elevees, tant pour le Δ[sup.15]C que le Δ[sup.15]N, que celles d'autres especes de souris. Les valeurs empiriques des taux de discrimination ont ensuite ete comparees fi des valeurs calculees par une autre methode basee sur des valeurs generiques et se sont averees differentes, donnant a penser que l'utilisation de valeurs generiques n'est pas toujours bien avisee. Nos resultats soulignent la necessite d'une meilleure comprehension des hypotheses associees a l'utilisation de l'analyse des isotopes stables pour etudier le regime alimentaire, et nous suggerons que l'etude d'une seule espece dans des conditions de captivite constitue une methode ideale pour commencer a verifier ces hypotheses. [Traduit par la Redaction] Mots-cles: Acomys spinosissimus, discrimination, restriction alimentaire, souris epineuse, isotope stable., Introduction Stable isotope analysis has been used to answer a number of questions relating to foraging and diet; for example, quantifying reliance on different food sources (Robb et al. 2012), [...]

While the role of littoral food sources in shallow lakes has been widely investigated, uncertainties still exist about the relevance of such sources for deep lakes. Here we report quantitative estimates for the contribution of littoral versus pelagic sources in supporting the three most important planktivorous fish of a deep, large, subalpine lake in Italy. Contributions of pelagic (p) and littoral (q) signatures of δ[sup.13]C and δ[sup.15]N stable isotopes were detected in fish muscular tissue by applying a dynamic baseline mixing model. This model integrates tissue-specific metabolic turnover (m) and fish growth (k) rates over baselines δ[sup.13]C seasonality. Annual fluctuations for both pelagic and littoral baselines were not negligible (ΔC = 10 ‰ and 89 ‰, respectively). We calculated that they could not be ignored, since contributions of pelagic and littoral signatures would be largely underestimated (up to 30% p and 13% q for whitefish (Coregonus lavaretus) and roach (Rutilus rutilus), respectively). When fish relied upon pelagic consumers, stepwise [sup.15]N-enrichment (E) of pelagic preys linearly decreased with prey-size-specific predation pressure. Therefore, longer food webs would be proportionally less stepwise [sup.15]N-enriched than shorter ones. Si le role des sources de nourritures littorales dans les lacs peu profonds a fait l'objet de nombreuses etudes, des incertitudes persistent quant a la pertinence de ces sources en ce qui concerne les lacs profonds. Nous rendons compte d'estimations quantitatives des contributions de sources littorales et pelagiques aux regimes alimentaires des trois plus importants poissons planctonivores d'un grand lac subalpin profond en Italie. Des contributions de signatures d'isotopes stables (δ[sup.13]C et δ[sup.15]N) pelagiques (p) et littorales (q) ont ete detectees dans les tissus musculaires des poissons en appliquant un modele de melange integrant des conditions de base dynamiques. Ce modele integre des taux de renouvellement metabolique (m) propres aux tissus et de croissance des poissons (k)a la saisonnalite des signatures de δ[sup.13]C de base. Les fluctuations annuelles des conditions de base tant pelagiques que littorales n'etaient pas negligeables (ΔC = 10 ‰ et 8 ‰, respectivement). Nous avons determine que ne pas tenir compte de ces fluctuations entramerait une forte sous-estimation des contributions des signatures pelagiques et littorales (jusqu'a 30%dup et 13 % du q pour les coregones (Coregonus lavaretus) et les gardons (Rutilus rutilus), respectivement). Dans les cas ou les poissons dependaient de consommateurs pelagiques, l'enrichissement sequentiel en [sup.15]N(E) des proies pelagiques diminuait de maniere lineaire parallelement a la pression de predation pour la taille de proies concernee. Les longs reseaux trophiques seraient donc proportionnellement moins enrichis sequentiellement en [sup.15]N que les reseaux plus courts. [Traduit par la Redaction], Introduction The strong reliance between autochthonous and allochthonous carbon (C) sources is well documented in shallow lakes (e.g., Pulido-Villena et al. 2005; Bertolo et al. 2005; Ask et al. 2009; [...]

INTRODUCTION At present, there are a number of theoretical and experimental works in the literature, which consider the methodological potential of isotopic mass spectrometry for determining the regional areas of [...], Distribution of [sup.13]C/[sup.12]C isotopes in vegetative (roots, grapevine, leaves) and generative (berries) parts of vine plants of the West European genetically different varieties Cabernet Sauvignon and Aligote growing on soils of Krasnodar krai and Rostov oblast, as well as autochthonous varieties Sibirkovy and Krasnostop Zolotovsky growing in Rostov oblast, has been studied using isotopic mass spectrometry methods. It has been shown that the variations of δ[sup.13]C values in plant tissues and berries are related to the climatic conditions of plant growth: moisture (a sum of annual precipitation) and temperature (a sum of annual effective temperatures). The carbon isotope ratios of vegetative and generative parts of vine plants have been found to be noticeably affected by vine varieties. The different [sup.13]C contents in ethanol produced from wine of the Aligote and Cabernet Sauvignon varieties grown in two Russian vineyard regions are due to vine growth conditions, variety attribution and wine production techniques. An analytically significant parameter determined as exemplified by the Aligote and Cabernet Sauvignon varieties in fermentation of vine harvested in different seasons and in both vineyard regions was an increased [sup.13]C content in ethanol with respect to dry (non-volatile) residue in wine after distillation of ethanol. This characteristic has been determined by a systematic difference of about 1-2‰ between the δ[sup.13]C value of ethanol and the dry residue. A relative constancy in the carbon isotope composition of ethanol and of the dry residue in the final product is the basis for determining the authenticity of grape wines by means of isotopic mass spectrometry irrespective of natural factors. Keywords: isotopic mass spectrometry, carbon isotope content, vine plant variety, roots, vine, leaves, berries, ethanol, soil, climate DOI: 10.1134/S106193481313011X

There are two leading hypotheses for the documented large-amplitude (12) Neoproterozoic carbon isotope anomalies. The first proposal is that the Neoproterozoic deep ocean carried a massive dissolved organic carbon (DOC) [...], Interpretations of major climatic and biological events in Earth history are, in large part, derived from the stable carbon isotope records of carbonate rocks and sedimentary organic matter (1,2). Neoproterozoic carbonate records contain unusual and large negative isotopic anomalies within long periods (10-100 million years) characterized by δ[sup.13]C in carbonate (δ[sup.13][C.sub.carb]) enriched to more than +5 per mil. Classically, δ[sup.13][C.sub.carb] is interpreted as a metric of the relative fraction of carbon buried as organic matter in marine sediments (2-4), which can be linked to oxygen accumulation through the stoichiometry of primary production (3,5). If a change in the isotopic composition of marine dissolved inorganic carbon is responsible for these excursions, it is expected that records of δ[sup.13][C.sub.carb] and δ[sup.13]C in organic carbon (δ[sup.13][C.sub.org]) will covary, offset by the fractionation imparted by primary production (5). The documentation of several Neoproterozoic δ[sup.13][C.sub.carb] excursions that are decoupled from δ[sup.13][C.sub.org], however, indicates that other mechanisms (6-8) may account for these excursions. Here we present δ[sup.13]C data from Mongolia, northwest Canada and Namibia that capture multiple large-amplitude (over 10 per mil) negative carbon isotope anomalies, and use these data in a new quantitative mixing model to examine the behaviour of the Neoproterozoic carbon cycle. We find that carbonate and organic carbon isotope data from Mongolia and Canada are tightly coupled through multiple δ[sup.13][C.sub.carb] excursions, quantitatively ruling out previously suggested alternative explanations, such as diagenesis (7,8) or the presence and terminal oxidation of a large marine dissolved organic carbon reservoir (6). Our data from Namibia, which do not record isotopic covariance, can be explained by simple mixing with a detrital flux of organic matter. We thus interpret δ[sup.13][C.sub.carb] anomalies as recording a primary perturbation to the surface carbon cycle. This interpretation requires the revisiting of models linking drastic isotope excursions to deep ocean oxygenation and the opening of environments capable of supporting animals (9-11).

Selecting the proper stock type for reforestation on dry sites can be critical for the long-term survival and growth of seedlings. In this study, we use a novel approach to understand stock type selection on a site where drought was induced with vegetative competition. Three ponderosa pine (Pinus ponderosa Lawson & C. Lawson var. ponderosa C. Lawson) seedling stock types were planted in the field and subjected to three levels of competition. Winter wheat (Triticum aestivum L. em.) was sown in three densities (0, 150, and 300 plants * [m.sup.-2]) and was successfully used as a model competitor to create drought conditions. High rates of net photosynthesis (A) indicated that seedlings with adequate soil moisture and without vegetative competition were established within three weeks. Conversely, low A, low soil moisture, and low predawn water potential measurements indicated that seedlings planted with vegetative competition were moisture-stressed and not established. Drought conditions created by the wheat caused 100% mortality among smaller stock types, whereas the largest stock type had a 63%-75% mortality rate. Measures of stable carbon isotopes showed stratification based on water availability, with significant [δ.sup.13] C enrichment in competition treatments. Soil moisture is critical for seedlings to establish quickly after planting. Our data suggest that proper stock type selection on drought-or vegetation-prone sites can confer survival and growth benefits. Resume: Le choix du type de stock approprie pour le reboisement des stations seches peut etre determinant pour la survie et la croissance a long terme des semis. Dans cette etude, nous avons utilise une nouvelle approche pour comprendre comment choisir le type de stock dans une station ou la secheresse a ete provoquee par la vegetation competitrice. Trois types de stock de semis de pin ponderosa typique (Pinus ponderosa Lawson & C. Lawson var. ponderosa C. Lawson) ont ete plantes au champ et soumis a trois niveaux de competition. Le ble d'hiver (Triticum aestivum L. em.) a ete seme a trois densites (0, 150 et 300 plants * [m.sup.-2]) et a ete utilise avec succes comme competiteur modele pour creer des conditions de secheresse. Des taux eleves de photosynthese nette (A) indiquaient que les semis s'etaient etablis apres moins de trois semaines si l'humidite du sol etait adequate et qu'il n'y avait pas de vegetation competitrice. A l'inverse, de faibles valeurs de A, d'humidite du sol et de potentiel hydrique de base indiquaient que les semis plantes en presence de vegetation competitrice subissaient un stress hydrique et ne s'etaient pas etablis. Les conditions de secheresse engendree par le ble ont cause 100 % de mortalite chez les types de stock plus petits tandis que les types de stock les plus gros avaient un taux de mortalite de 63-75 %. Des mesures des isotopes stables de carbone ont montre que qu'il y avait une stratification basee sur la disponibilite de l'eau qui se traduisait par un enrichissement significatif de [δ.sup.13] C dans les traitements ou il y avait de la competition. L'humidite du sol est cruciale pour que les semis s'etablissent rapidement apres la plantation. Nos donnees indiquent que le choix du type de stock approprie dans les stations sujettes a la secheresse ou la vegetation peut avoir un effet benefique sur la survie et la croissance. [Traduit par la Redaction], Introduction The challenges of dry-site reforestation are not new, but they continue to limit reforestation success. Normal climate patterns in the northwestern USA include a pronounced dry season, which causes [...]

To test the hypothesis that stable isotope ratios from marine organisms vary, the [delta].sup.15N and [delta].sup.13C values from fish and squid collected in Alaskan waters were measured across years (1997, 2000, and 2005), seasons, geographic locations, and different size/age classes, and between muscle tissue and whole animals. Temporal, geographic, and ontogenetic differences in stable isotope ratios ranged from 0.5-2.5â° ([delta].sup.15N) to 0.5-2.0â° ([delta].sup.13C). Twenty-one comparisons of stable isotope values between whole organisms and muscle tissue revealed only four small differences each for [delta].sup.15N and [delta].sup.13C, making costly and space prohibitive collection of whole animals unnecessary. The data from this study indicate that significant variations of stable isotope values from animals in marine systems necessitates collection of prey and predator tissues from the same time and place for best interpretation of stable isotope analysis in foraging ecology studies., Author(s): Carolyn M. Kurle [sup.1] , Elizabeth H. Sinclair [sup.2] , Ann E. Edwards [sup.3] [sup.4] , Carolyn J. Gudmundson [sup.2] Author Affiliations: (1) grid.266100.3, 0000000121074242, Division of Biological Sciences, [...]

Anguilla japonica leptocephali are transported from their offshore spawning area to their recruitment areas in East Asia, but their depth distributions, food sources and feeding are still poorly known. This study analyzed carbon and nitrogen stable isotope ratios of leptocephali of A. japonica, Ariosoma major and Ariosoma spp., and of particulate organic matter (POM), their likely food source, at five different depths in 2004-2009. We used mixing models to show that A. japonica appeared to be feeding at depths between 5 and 50 m, but sometimes deeper. A. major appeared to have a tendency of mostly feeding at depths of 50 m or shallower. Although the A. japonica and Ariosoma spp. collected in the same area during the leptocephalus stage appeared to have different feeding ecologies possibly related to different types of POM, their different depth distributions, sizes and transport histories may also help explain these differences., Author(s): Sachie Miyazaki [sup.1] , Hee-Yong Kim [sup.3] , Kei Zenimoto [sup.1] , Takashi Kitagawa [sup.1] , Michael J. Miller [sup.2] , Shingo Kimura [sup.1] Author Affiliations: (1) grid.26999.3d, 000000012151536X, [...]

Thousands of carbon isotope data have been reported for Neoproterozoic successions in the past decade (4-8), yet the full palaeo- environmental significance of these data is still largely unappreciated. In [...], The snowball Earth hypothesis postulates that the planet was entirely covered by ice for millions of years in the Neoproterozoic era, in a self-enhanced glaciation caused by the high albedo of the ice-covered planet. In a hard-snowball picture, the subsequent rapid unfreezing resulted from an ultra-greenhouse event attributed to the buildup of volcanic carbon dioxide (C[O.sub.2]) during glaciation (1). High partial pressures of atmospheric C[O.sub.2] ([MATHEMATICAL EXPRESSION NOT REPRODUCIBLE IN ASCII]; from 20,000 to 90,000 p.p.m.v.) in the aftermath of the Marinoan glaciation (~635 Myr ago) have been inferred from both boron and triple oxygen isotopes (2,3). These [MATHEMATICAL EXPRESSION NOT REPRODUCIBLE IN ASCII] values are 50 to 225 times higher than present-day levels. Here, we re-evaluate these estimates using paired carbon isotopic data for carbonate layers that cap Neoproterozoic glacial deposits and are considered to record post-glacial sea level rise1. The new data reported here for Brazilian cap carbonates, together with previous ones for time-equivalent units (4-8), provide [MATHEMATICAL EXPRESSION NOT REPRODUCIBLE IN ASCII] estimates lower than 3,200 p.p.m.v.--and possibly as low as the current value of ~400 p.p.m.v. Our new constraint, and our reinterpretation of the boron and triple oxygen isotope data, provide a completely different picture of the late Neoproterozoic environment, with low atmospheric concentrations of carbon dioxide and oxygen that are inconsistent with a hard-snowball Earth.

The stable carbon isotope composition of animal tissues represents the weighted sum of the variety of food sources eaten. If sources differ in digestibility, tissues may overrepresent intake of more digestible items and faeces may overrepresent less digestible items. We tested this idea using whole blood and faeces of goats (Capra hircus L., 1758) fed different food mixtures of [C.sub.3] lucerne (Medicago sativa L.) and [C.sub.4] grass (Themeda triandra Forssk.). Although blood and faecal δ[sup.13]C values were broadly consistent with diet, results indicate mismatch between consumer and diet isotope compositions: both materials overrepresented the [C.sub.3] (lucerne) component of diets. Lucerne had lower fibre digestibility than T. triandra, which explains the results for faeces, whereas underrepresentation of dietary [C.sub.4] in blood is consistent with low protein content of the grass hay. A diet switch experiment revealed an important difference in [sup.13]C-incorporation rates across diets, which were slower for grass than lucerne diets, and in fact equilibrium states were not reached for all diets. Although more research is needed to link digestive kinetics with isotope incorporation, these results provide evidence for nonlinear relationships between consumers and their diets, invoking concerns about the conceptual value of 'discrimination factors' as the prime currency for contemporary isotope ecology. La composition en isotopes stables de carbone dans les tissus animaux represente la somme ponderee de la variete des sources de la nourriture consommee. S'il y a des differences de digestibilite entre les sources, les tissus peuvent fournir une surrepresentation de l'ingestion des aliments plus digestibles et les feces une surrepresentation des aliments moins digestibles. Nous avons teste cet enonce par l'analyse du sang et des feces de chevres (Capra hircus L., 1758) nourries de divers melanges de luzerne (Medicago sativa L.; une plante [C.sub.3] )etd'herbes [C.sub.4] (Themeda triandra Forssk.). Bien que les valeurs de δ[sup.13]C du sang et des feces correspondent globalement au regime alimentaire, les resultats indiquent un mesappariement entre les compositions isotopiques du consommateur et de son regime alimentaire; les deux materiaux surrepresentent la composante [C.sub.3] (luzerne) du regime. La digestibilite des fibres de luzerne est plus faible que celle de T. triandra, ce qui explique les resultats obtenus avec les feces, alors que la sous-representation du [C.sub.4] alimentaire dans le sang correspond au faible contenu proteinique du foin d'herbe. Une experience de changement de regime montre une importante difference dans les taux d'incorporation de [sup.13]C entre les regimes; ceux-ci sont plus lents pour les regimes d'herbe que de luzerne et l' etat d' equilibre n' est pas atteint dans tous les regimes. Bien que des recherches additionnelles soient necessaires pour relier la cinetique de la digestion a l' incorporation des isotopes, nos resultats fournissent des preuves que les relations entre les consommateurs et leur regime alimentaire n'est pas lineaire, ce qui genere des doutes sur la valeur conceptuelle des << facteurs de discrimination >> comme outils de change couramment utilises dans l'ecologie actuelle des isotopes. [Traduit par la Redaction], Introduction Stable isotope analysis is a common approach to study animal diets and nutrient flow in food webs (Peterson and Fry 1987; Newsome et al. 2007; Crawford et al. 2008). [...]

Analysis of carbon ([sup.13]C/[sup.12]C) and nitrogen ([sup.15]N/[sup.14]N) stable isotope ratios (hereafter [delta][sup.13]C and [delta][sup.15]N, respectively) in animal tissues is a powerful tool in food-web studies. However, isotopic ratios of prey are not transmitted directly to a consumer, as a diet-tissue discrimination factor (denoted A) occurs between sources and consumer's tissues. An accurate assessment of the diet of a consumer with stable isotopes thus requires that the [DELTA][sup.13]C and [DELTA][sup.15]N of the studied species are known. Our aim was to establish [DELTA][sup.13]C and [DELTA][sup.15]N values in the Snowy Owl (Bubo scandiacus (L., 1758)). Moreover, we assessed the potential effect of ethanol preservation of blood samples on [delta][sup.13]C and [delta][sup.15]N values. We kept four captive adult Snowy Owls on a pure diet of mice for [greater than or equal to] 6 weeks. We then collected mouse muscle and blood samples from the owls and analyzed their [delta][sup.13]C and [delta][sup.15]N values. [DELTA][sup.13]C and [DELTA][sup.15]N values (mean [+ or -] SE) for owl blood were +0.3 [per thousand] [+ or -] 0.2 [per thousand] and +1.9 [per thousand] [+ or -] 0.1 [per thousand], respectively. These values are the first discrimination factors ever reported in Strigiformes and are lower, for [DELTA][sup.15]N, than those obtained in terrestrial carnivores and other bird species, including falcons. Preservation in ethanol did not significantly affect [delta][sup.13]C and [delta][sup.15]N values. L'analyse des ratios isotopiques de carbone ([sup.13]C/[sup.12]C) et d'azote ([sup.15]N/[sup.14]N) (symbolises par [delta][sup.13]C et [delta][sup.15]N respectivement) dans les tissus animaux est un outil puissant pour l' etude des reseaux trophiques. Cependant, les ratios isotopiques des proies ne sont pas transmis directement au consommateur et un facteur de discrimination (note [DELTA]) est observe entre les ratios des sources et ceux du consommateur. La determination exacte du regime alimentaire d'un consommateur a l'aide des isotopes stables demande donc une connaissance des [DELTA][sup.13]C et [DELTA][sup.15]N chez l'espece a l'etude. Notre objectif etait de determiner les valeurs de [DELTA][sup.13]C et [DELTA][sup.15]N chez le harfang des neiges (Bubo scandiacus (L., 1758)). De plus, nous voulions determiner l'impact potentiel de la conservation d'echantillons sanguins dans une solution d'ethanol 70 % sur les valeurs de [delta][sup.13]Cet [delta][sup.15]N. Nous avons garde quatre harfangs des neiges en captivite, nourris exclusivement de souris pendant [greater than or equal to] 6 semaines. Nous avons ensuite recolte des echantillons sanguins des oiseaux et des muscles de souris et nous avons determine leur signature de [delta][sup.13]C et de [delta][sup.15]N. Les valeurs de [DELTA][sup.13]C et [DELTA][sup.15]N (moyenne [+ or -] ES) du sang chez le harfang des neiges sont de +0,3 [per thousand] [+ or -] 0,2 [per thousand] et +1,9 [per thousand] [+ or -] 0,1 [per thousand], respectivement. Ces valeurs de discrimination sont les premieres rapportees a ce jour chez les strigiformes et elles sont plus faibles, pour l'azote, que celles observees chez les carnivores terrestres et d'autres especes d'oiseaux, incluant les faucons. La conservation des echantillons sanguins dans une solution d'ethanol 70 % n'as pas affecte significativement les valeurs de [delta][sup.13]C et de [delta][sup.15]N., Introduction Naturally occurring stable isotopes of carbon ([sup.13]C, [sup.12]C) and nitrogen ([sup.15]N, [sup.14]N) are present in every living organism and they occur under specific ratios (denoted [delta][sup.13]C and [delta][sup.15]N, respectively) [...]

We examined [δ.sup.15]N and [δ.sup.13]C values of feathers from nine species, belonging to three feeding guilds (herbivores, omnivores, and insectivores), of wild passerines at eight sites along an altitudinal gradient (339-2,876 m asl) within Taroko National Park, Taiwan. We examined: (1) if altitudinal patterns in feather [δ.sup.15]N and [δ.sup.13]C are consistent with previously published values for plants and soils, (2) if feather [δ.sup.15]N and [δ.sup.13]C differ among sites, and (3) if there are year-to-year and/or month-to-month fluctuations in feather [δ.sup.15]N and [δ.sup.13]C of the same birds. We found no simple relationship between feather isotope values and altitude. Feather [δ.sup.15]N values decreased significantly with increasing altitude for insectivores, but not for herbivores and omnivores. Feather [δ.sup.13]C values increased significantly with increasing altitude for herbivores and omnivores, but not for insectivores. Altitudinal trends in feather [δ.sup.15]N and [δ.sup.13]C values exhibit even more inconsistent patterns when data were analyzed by species; feather [δ.sup.15]N and [δ.sup.13]C values for some species increased significantly with increasing altitude, others decreased significantly with increasing altitude, and still others exhibited no significant relationship between isotopic values and altitude. The [R.sup.2] for the relationship between feather [δ.sup.15]N, [δ.sup.13]C values and altitude was generally low regardless of whether the analysis was by feeding guilds or species. This indicates much of the variation cannot be explained by altitude. There were either no significant differences between sites, or significant differences between some but not all sites when investigating [δ.sup.15]N or [δ.sup.13]C, whether by feeding guilds or by species. Our study suggests that carbon and nitrogen isotopes may be not useful markers to track altitudinal migration of montane passerines. Received 16 April 2010. Accepted 15 September 2010., Stable isotope analysis in animals is a powerful tool in reconstruction of diets (Hobson and Clark 1992), trophic levels (Kelly 2000), feeding habitats (Hobson and Sealy 1991, Cherel et al. [...]

Seabird populations contain large numbers of immatures--in some instances comprising >50% of the fully grown adults in the population. These birds are significant components of marine food webs and may contribute to compensatory recruitment and dispersal, but remain severely understudied. Here, we use GPS-PTTs, radio-tracking and analysis of stable carbon ([delta].sup.13C) and nitrogen ([delta].sup.15N) isotopes to investigate the movements and foraging ecology of immature seabirds. Our study focussed on immature northern gannets Morus bassanus aged 2-4 attending non-breeding aggregations alongside a large breeding colony. GPS-PTT tracking of five birds revealed that immatures have the ability to disperse widely during the breeding season, with some individuals potentially prospecting at other colonies. Overall, however, immatures were faithful to the colony of capture. During returns to the focal colony, immatures acted as central place foragers, conducted looping and commuting flights, and analysis of the variance in first-passage time revealed evidence of area-restricted search (ARS) behaviour. In addition, stable carbon ([delta].sup.13C) and nitrogen ([delta].sup.15N) isotope analyses indicate that immatures were isotopically segregated from breeders. Our findings provide insights into the foraging, prospecting and dispersal behaviour of immature seabirds, which may have important implications for understanding seabird ecology and conservation., Author(s): Stephen C. Votier [sup.1] , W. James Grecian [sup.1] , Samantha Patrick [sup.1] , Jason Newton [sup.2] Author Affiliations: (1) grid.11201.33, 0000000122190747, University of Plymouth, , PL4 8AA, Plymouth, [...]

Bacteriogenic iron oxides in natural environments are characterized by an abundance of ferrihydrite precipitates intermixed with bacterial structures that commonly resemble those produced by the lithoautotrophic microorganisms Gallionella ferruginea and Leptohtrix ochracea. These species have been inferred to play a causal role in the formation of bacteriogenic iron oxides, providing a pathway for the reduction of C[O.sub.2] and the depletion of [sup.13]C in the organic constituents of bacteriogenic iron oxides. In this study, stable carbon isotope fractionation was determined for bacteriogenic iron oxide samples collected from submarine hydrothermal vents (Axial Volcano, Juan de Fuca Ridge), subterranean (Aspo Hard Rock Laboratory, Sweden) and surficial (Chalk River, Canada) groundwater seeps, and cultures of G. ferruginea. Data were also collected from ferrihydrite samples lacking evidence of bacteria from Bounty Seamount in the vicinity of Pitcairn Island. The mean [delta][sup.13]C ([per thousand]) of ferrihydrite was determined to be -15.87 [per thousand] [+ or -] 4.96 [per thousand] for the samples from Axial Volcano, -24.97 [per thousand] [+ or -] 0.43 [per thousand] for Aspo, -27.80 [per thousand] [+ or -] 0.85 [per thousand] for Chalk River, -29.3 [per thousand] [+ or -] 0.2 [per thousand] for the microbial culture, and -8.43 [per thousand] [+ or -] 1.89 [per thousand] for the samples from Pitcairn. Samples with the highest concentration of organic carbon also had the lightest [delta][sup.13]C in a logarithmic relationship. The consistency of carbon isotope values in relation to the presence of iron-oxidizing bacteria from natural and laboratory samples is interpreted as the ability of these microorganisms to fractionate carbon. The potential of this fractionation to serve as a biosignature holds promise when the resistance of carbon and bacteriogenic ferrihydrite to diagenesis is taken into consideration. doi: 10.1130/G30986.1

[C.sub.4] plants are widely successful in the grass-dominated ecosystems of tropical, subtropical, and warm-temperate regions, largely as a result of their ability to limit photorespiration and improve water-use efficiency. A widely held paradigm is that low ( doi: 10.1130/G31117.1

Carbon dioxide is a primary component of the martian atmosphere and reacts readily with water and silicate rocks. Thus, the stable isotopic composition of C[O.sub.2] can reveal much about the history of volatiles on the planet. The Mars Phoenix spacecraft measurements of carbon isotopes [referenced to the Vienna Pee Dee belemnite (VPDB)] [[delta][sup.13][C.sub.VPDB] = -2.5 [+ or -] 4.3 per mil ([per thousand]] and oxygen isotopes [referenced to the Vienna standard mean ocean water (VSMOW)] ([delta][sup.18][O.sub.VSMOW] = 31.0 [+ or -] 5.7 [per thousand]), reported here, indicate that C[O.sub.2] is heavily influenced by modern volcanic degassing and equilibration with liquid water. When combined with data from the martian meteorites, a general model can be constructed that constrains the history of water, volcanism, atmospheric evolution, and weathering on Mars. This suggests that low-temperature water-rock interaction has been dominant throughout martian history, carbonate formation is active and ongoing, and recent volcanic degassing has prayed a substantial role in the composition of the modern atmosphere. 10.1126/science.1192863

Stable isotope analyses of animal tissues can be used to infer diet through application of mixing models. An important component in a mixing model is the incorporation of stable isotope discrimination factors so that isotopic shifts between diet and tissues built from the diet can be accounted for when comparing tissues to potential food sources. We determined the stable carbon and nitrogen isotopic discrimination factors between lipid-free diet and blood plasma, cellular blood, and adult chest contour feathers for captive female Spectacled Eiders (Somateria fischeri (Brandt, 1847)). Mean discrimination factors for blood components and feathers were either similar or slightly larger compared with previously studied species. Additionally, we determined the stable carbon isotope discrimination factors between dietary lipids and adipose tissue fatty acids using three adipose tissue biopsies from captive male Spectacled Eiders that were led three different diet treatments. Isotopic signatures of adipose tissue fatty acids closely reflected shifts in the diet and were either similar to or increased relative to diet. Our study provides a foundation for research using tissues as end-members in stable isotope nutrient allocation models and foraging ecology studies of Spectacled Eiders, and will provide the most applicable isotope data to date for sea ducks. Les analyses des isotopes stables des lissus animaux peuvcnt servir a deduire le regime alimentaire par l'ulilisation des modeles de melange. Une composante importante d'un modele de melange est l'incorporation des facteurs discriminants des isotopes stables de maniere a ce que les changemenis isotopiques entre le regime et les lissus elabores a partir de ce regime puissent etre expliques lors de la comparaison des tissus avec leurs sources potentielles de nourriture. Nous avons determine les facteurs discriminants pour les isotopes stables de carbone et d'azote entre un regime sans lipides et le plasma sanguin, le sang cellulaire et les plumes de contour de la poitrine chez des femelles de l'eider a lunettes (Somateria fischeri (Brandt, 1847)) en captivite. Les facteurs discriminants moyens pour les composantes du sang et les plumes sont ou bien semblables ou alors legerement plus eleves par rapport a ceux des especes etudiees anterieurement. De plus, nous avons determine les facteurs discriminants des isotopes stables entre les lipides du regime et les acides gras du tissu adipeux a l'aide de trois biopsies du tissu adipeux faites sur des males de l'eider a lunettes en captive nourris de trois regimes alimentaires experimentaux. Les signatures isotopiques des acides gras des tissus adipeux refletent avec exactitude les changemenis de regime et sont ou bien semblables ou alors elevees par comparaison au regime. Notre etude foumit une base pour la recherche qui utilise les lissus comme points terminaux dans les modeles d'allocation des nutriments bases sur les isotopes stables et pour les etudes ecologiques de l'alimentation des eiders a lunettes et elle presente les donnees isotopiques les plus appropriees a ce jour pour les canards de mer. [Traduit par la Redaction], Introduction Analysis of stable isotopes in avian tissues is a valuable tool for tracking migration, inferring diet, and evaluating foraging ecology and resource allocation (Kelly 2000; Rubenstein and Hobson 2004; [...]

We present a new method for analyzing the [delta][sup.13]C isotopic composition of several oxygenated volatile organic compounds (OVOCs) from direct sources and ambient atmospheric samples. Guided by the requirements for analysis of trace components in air, a gas chromatograph isotope ratio mass spectrometer (GC-IRMS) system was developed with the goal of increasing sensitivity, reducing dead-volume and peak band broadening, optimizing combustion and water removal, and decreasing the split ratio to the isotope ratio mass spectrometer (IRMS). The technique relies on a two-stage preconcentration system, a low-volume capillary reactor and water trap, and a balanced reference gas delivery system. The instrument's measurement precision is 0.6 to 2.9[per thousand] (1[sigma]), and results indicate that negligible sample fractionation occurs during gas sampiing. Measured [delta][sup.13]C values have a minor dependence on sample size; linearity for acetone was 0.06[per thousand] ng [C.sup.-1] and was best over 1 - 10 ng C. Sensitivity is ~10 times greater than similar instrumentation designs, incorporates the use of a diluted working reference gas (0.1% C[O.sub.2]), and requires collection of >0.7 ng C to produce accurate and precise results. With this detection limit, a 1.0 L sample of ambient air provides sufficient carbon for isotopic analysis. Emissions from vegetation and vehicle exhaust are compared and show clear differences in isotopic signatures. Ambient samples collected in metropolitan Miami and the Everglades National Park can be differentiated and reflect multiple sources and sinks affecting a single sampling location. Vehicle exhaust emissions of ethanol, and those collected in metropolitan Miami, have anomalously enriched [delta][sup.13]C values ranging from -5.0 to -17.2[per thousand]; we attribute this result to ethanol's origin from corn and use as an additive in automotive fuels. 10.1021/ac1007442

The stable carbon isotope compositions of 2-methyltetrols, biomarker compounds for secondary organic aerosols formed from isoprene in the atmosphere, have been determined by gas chromatography/combustion/ isotope ratio mass spectrometry (GC/C/IRMS). In this work, isoprene with various [delta][sup.13]C values was used to produce 2-methyltetrols via an oxidation reaction with hydrogen peroxide in sulfuric acid under direct sunlight. The target compounds with different stable carbon isotope compositions were then derivatized by methylboronic acid with a known [delta][sup.13]C value and measured by GC/C/IRMS. With [delta][sup.13]C values of 2-methyltetrols and methylboronic acid predetermined, isotopic fractionation is evaluated for the derivatization process. Through reduplicate [delta][sup.13]C measurements, the carbon isotope analysis achieved excellent reproducibility and high accuracy with an average error of 10.1021/ac100214p

Eocene Thermal Maximum 2 (ETM2) and H2 were two short-lived global warming events that occurred ~2 m.y. after the Paleocene--Eocene thermal maximum (PETM, ca. 56 Ma). We have generated benthic foraminiferal stable carbon and oxygen isotope records of four sites along a depth transect on Walvis Ridge (~3.5-1.5 km paleodepth, southeast Atlantic Ocean) and one site on Maud Rise (Weddell Sea) to constrain the pattern and magnitude of their carbon isotope excursions (CIEs) and deep-sea warming. At all sites, ETM2 is characterized by ~3[degrees]C warming and a -1.4[per thousand] CIE. The H2 event that occurred ~100 k.y. later is associated with ~2[degrees]C warming and a -0.8[per thousand] CIE. The magnitudes of the [delta][sup.13]C and [delta][sup.18]O excursions of both events are significantly smaller than those during the PETM, but their coherent relation indicates that the [delta][sup.13]C change of the exogenic carbon pool was similarly related to warming during these events, despite the much more gradual and transitioned onset of ETM2 and H2. doi: 10.1130/G30777.1

Introduction You are what you eat! This slogan indicates that the composition of body tissues reflects the dietary intake of the individual. All atoms in human tissues, except hydrogen and [...], Background/Objectives: The content of [sup.13]C and [sup.15]N isotopes is higher in marine than in terrestrial food. [sup.13]C and [sup.15]N in human tissue therefore reflects the relative proportions of marine and terrestrial food consumed by the individual. The objective of this study was to measure [sup.13]C and [sup.15]N in liver tissue from Greenlandic Inuit and Danes. Subjects/Methods: Normal liver tissue was obtained at autopsy in 1992-1994 from 60 Inuit with a median age of 61 years (range 25-83) and in 1986 from 15 ethnic Danes with a median age of 84 years (range 66-93). By sieving, liver tissue was separated in a 'cellular fraction' and a 'connective tissue fraction'. [sup.13]C and [sup.15]N in dry liver tissue was measured on a mass spectrometer. [δ.sup.13]C indicates the [sup.13]C content relative to the IAEA-CH-6 reference standard. [δ.sup.15]N indicates [sup.15]N content relative to the atmospheric nitrogen reference standard. Results: Inuit: median [δ.sup.13]C was -21.2% in cellular and -20.0% in connective tissue fractions (P = 0.001). Median [δ.sup.15]N was 10.6% in both cellular and connective tissue fractions. Body mass index was negatively correlated with [δ.sup.13]C in the connective tissue fraction ([r.sub.s] = -0.42, P = 0.057). Danes: median [δ.sup.13]C was -27.0% in cellular and -24.3% in connective tissue fractions (P = 0.11). Median [δ.sup.15]N was 9.5% in cellular and 8.9% in connective tissue fractions (P = 0.5). Inuit had higher [δ.sup.13]C than Danes in both cellular and connective tissue fractions (P< 0.001) as well as higher [δ.sup.15]N in the cellular fraction (P = 0.01). Conclusions: Inuit showed considerable variation in the ratio between marine and terrestrial food consumption, reflecting a vanishing hunter culture where elderly Inuit still adhere to the traditional hunters food with a high content of marine food, whereas the younger urbanized Inuit population consume food with a lower content of marine food and a higher content of terrestrial food. Danes consumed food of almost exclusively terrestrial origin. The present [sup.13]C and [sup.15]N analyses are in accordance with the dietary patterns obtained by dietary surveys. European Journal of Clinical Nutrition (2010) 64, 739-744; doi: 10.1038/ejcn.2010.67; published online 2 June 2010 Keywords: [sup.13]carbon; Denmark; Eskimos; Greenland; Inuit; liver; mass spectrometry; [sup.15]nitrogen

The end-Permian mass extinction horizon is marked by an abrupt shift in style of carbonate sedimentation and a negative excursion in the carbon isotope ([delta][sup.13]C) composition of carbonate minerals. Several extinction scenarios consistent with these observations have been put forward. Secular variation in the calcium isotope ([delta][sup.44/40]Ca) composition of marine sediments provides a tool for distinguishing among these possibilities and thereby constraining the causes of mass extinction. Here we report [delta][sup.44/40]Ca across the Permian-Triassic boundary from marine limestone in south China. The [delta][sup.44/40]Ca exhibits a transient negative excursion of ~0.3[per thousand] over a few hundred thousand years or less, which we interpret to reflect a change in the global [delta][sup.44/40]Ca composition of seawater. C[O.sub.2]-driven ocean acidification best explains the coincidence of the [delta][sup.44/40]Ca excursion with negative excursions in the [delta][sup.13]C of carbonates and organic matter and the preferential extinction of heavily calcified marine animals. Calcium isotope constraints on carbon cycle calculations suggest that the average [delta][sup.13]C of C[O.sub.2] released was heavier than -28[per thousand] and more likely near -15[per thousand]; these values indicate a source containing substantial amounts of mantle- or carbonate-derived carbon. Collectively, the results point toward Siberian Trap volcanism as the trigger of mass extinction. doi/10.1073/pnas.0914065107

A perturbation in the carbon-isotope record at the time of the Pliensbachian-Toarcian boundary (~ 184 Ma) in the Early Jurassic is reported, based on new data from Yorkshire, England. Two sharp [delta][sup.13][C.sub.org] negative excursions, each with a magnitude of ~ -2.5 [per thousand] and reaching minimum values of -28.5 %o, are recorded in the bulk organic-matter record in sediments of latest Pliensbachian to earliest Toarcian age. A similar pattern of negative carbon-isotope excursions has been observed at the stage boundary in the SW European section at Peniche, Portugal in [delta][sup.13][C.sub.carbonate], [delta][sup.13][C.sub.wood] and [delta][sup.13][C.sub.brachiopod] records. The isotopic excursion is of interest when considering the genesis and development of the later Toarcian Oceanic Anoxic Event (OAE), as well as the second-order global extinction event that spans the stage boundary. Furthermore, the isotope excursion potentially provides a chemostratigraphic marker for recognition of the stage boundary, which is currently achieved on the basis of different ammonite faunas in the NW European and Tethyan realms. Keywords: Jurassic, Toarcian, Pliensbachian, carbon-isotope, excursion. doi: 10.1017/S0016756809990458

The stable isotopic compositions of nitrogen and carbon in animal tissues reflect diet. However, factors other than diet can also affect these stable isotope ratios, leading to misinterpretations of diet composition. To test the hypothesis that variation in metabolic rate alters the isotopic compositions of tissues, deer mice (Peromyscus maniculatus (Wagner, 1845)) were kept at three temperatures (thermoneutral (23°C), cool (5°C), and cold (-10°C)) and fed ad libitum. The changes in carbon and nitrogen isotope compositions of liver associated with the thermoneutral versus cool and cold conditions were very small in comparison with those arising from differences in diet. We conclude that temperature-induced variations in metabolic rate are insufficient to produce differences in the stable carbon or nitrogen isotope compositions that could be mistaken for changes in diet. Les compositions d'isotopes stables d'azote et de carbone dans les tissus animaux refletent le regime alimentaire. Cependant, des facteurs autres que le regime peuvent affecter ces rapports d'isotopes stables, ce qui entraine des interpretations erronees de la composition du regime alimentaire. Afin de tester l'hypothese qui veut que la variation du taux metabolique affecte la composition isotopique des tissus, nous avons garde des souris du crepuscule (Peromyscus maniculatus (Wagner, 1845)) a trois temperatures differentes, soit des regimes thermiques neutre (23°C), frais (5°C) et froid (-10°C), et les avons nourries a volonte. Les modifications dans les compositions d'isotopes de carbone et d'azote dans le foie associees au regime thermique neutre par rapport a ceux des regimes frais et froids sont tres petites par comparaison a celles qui proviennent de differences de regime alimentaire. Nous en concluons que les variations du taux metabolique causees par la temperature ne sont pas assez importantes pour produire des differences de composition des isotopes stables de carbone et d'azote qui pourraient etre interpretees par erreur comme des changements de regime alimentaire. [Traduit par la Redaction], Introduction Measurement of stable carbon ([sup.13]C/[sup.12]C) and nitrogen ([sup.15]N/[sup.14]N) isotope ratios is commonly undertaken in ecological studies because the compositions of tissues reflect the composition of the diet (Kelly 2000). [...]

Radiocarbon ([sup.14]C) is a radioactive isotope that is useful for determining the age and cycling of carbon-based materials in the Earth system. Compound specific radiocarbon analysis (CSRA) provides powerful insight into the turnover of individual components that make up the carbon cycle. Extraneous or nonspecific background carbon ([C.sub.ex]) is added during sample processing and subsequent isolation of CSRA samples. Here, we evaluate the quantity and radiocarbon signature of [C.sub.ex] added from two sources: preparative capillary gas chromatography (PCGC, [C.sub.PCGC] and chemical preparation of CSRA of black carbon samples ([C.sub.chemistry]). We evaluated the blank directly using process blanks and indirectly by quantifying the difference in the isotopic composition between processed and unprocessed samples for a range of sample sizes. The direct and indirect assessment of [C.sub.chemistry+PCGC] agree, both in magnitude and radiocarbon value (1.1 [+ or -] 0.5 [micro]g of C, fraction modern = 0.2). Half of the [C.sub.ex] is introduced before PCGC isolation, likely from coeluting compounds in solvents used in the extraction method. The magnitude of propagated uncertainties of CSRA samples are a function of sample size and collection duration. Small samples collected for a brief amount of time have a smaller propagated [sup.14]C uncertainty than larger samples collected for a longer period of time. CSRA users are cautioned to consider the magnitude of uncertainty they require for their system of interest, to frequently evaluate the magnitude of [C.sub.ex] added during sampling processing, and to avoid isolating samples [less than or equal to] 5 [micro]g of carbon. 10.1021/ac901922s

Stable isotope analysis can be used to document dietary changes within the lifetimes of individuals and may prove useful for investigating fallback food consumption in modern, historical, and ancient primates. Feces, hair, and enamel are all suitable materials for such analysis, and each has its own benefits and limitations. Feces provide highly resolved temporal dietary data, but are generally limited to providing dietary information about modern individuals and require labor-intensive sample collection and analysis. Hair provides less well-resolved data, but has the advantage that one or a few hair strands can provide evidence of dietary change over months or years. Hair is also available in museum collections, making it possible to investigate the diets of historical specimens. Enamel provides the poorest temporal resolution of these materials, but is often preserved for millions of years, allowing examination of dietary change in deep time. We briefly discuss the use of carbon isotope data as it pertains to recent thinking about fallback food consumption in ancient hominins and suggest that we may need to rethink the functional significance of the australopith masticatory package. Am J Phys Anthropol 140:661-670, 2009. KEY WORDS stable isotopes; feeding ecology; fallback foods; hominins; australopiths; dental microwear DOI 10.1002/ajpa.21111

During the Palaeocene and Eocene Epochs (65.5-33.9 Ma) the Earth experienced the warmest conditions of the Cenozoic. This Palaeogene greenhouse episode is characterized by several short-lived negative carbon isotope ([delta][sup.13]C) excursions, which are usually interpreted as transient warming events ('hyperthermals') as indicated by rising temperatures of surface and bottom waters, and accompanied carbonate dissolution in deep-sea settings. Among these events, the Palaeocene-Eocene Thermal Maximum (PETM, c. 55.5 Ma) is globally the best documented and most prominent. Further negative [delta][sup.13]C anomalies have recently been identified in the Eocene, but the early to middle Palaeocene has mostly been neglected. Here, benthic foraminiferal [delta][sup.13]C records are presented from four upper Danian-lower Selandian sections in the Nile Basin (eastern Egypt). All records show a negative [delta][sup.13]C shift with an amplitude of up to 2[per thousand] at the base of planktonic foraminiferal subzone P3b (c. 61 Ma). The supra-regional nature of this event is emphasized by correlation with a well-dated, similar [delta][sup.13]C record from Zumaia (Spain). Lithological changes, the [delta][sup.13]C signature and biotic responses strongly resemble those of the PETM in Egypt, which leads to the hypothesis that this 'Latest Danian Event' (LDE) may represent another early Palaeocene hyperthermal. doi: 10.1144/0016-76492008-104.