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The vapor pressure deficit reflects the difference between how much moisture the atmosphere could and actually does hold, a factor that fundamentally affects evapotranspiration, ecosystem functioning, and vegetation carbon uptake. Its spatial variability and long-term trends under natural versushuman-influenced climate are poorly known despite being essential for predicting future effects on natural ecosystems and human societies such as crop yield, wildfires, and health. Here we combine regionally distinct reconstructions of pre-industrial summer vapor pressure deficit variability from Europe’s largest oxygen-isotope network of tree-ring cellulose with observational records and Earth system model simulations with and without human forcing included. We demonstrate that an intensification of atmospheric drying during the recent decades across different European target regions is unprecedented in a pre-industrial context and that it is attributed to human influence with more than 98% probability. The magnitude of this trend is largest in Western and Central Europe, the Alps and Pyrenees region, and the smallest in southern Fennoscandia. In view of the extreme drought and compound events of the recent years, further atmospheric drying poses an enhanced risk to vegetation, specifically in the densely populated areas of the European temperate lowlands.

Quantitative nuclear magnetic resonance (NMR) for isotopic measurements, known as irm-NMR (isotope ratio measured by NMR), is well suited for the quantitation of 13C-isotopomers in position-specific isotope analysis and thus for measuring the carbon isotope composition (δ13C, mUr) in C-atom positions. Irm-NMR has already been used with glucose after derivatization to study sugar metabolism in plants. However, up to now, irm-NMR has exploited a “single-pulse” sequence and requires a relatively large amount of material and long experimental time, precluding many applications with biological tissues or extracts. To reduce the required amount of sample, we investigated the use of 2D-NMR analysis. We adapted and optimized the NMR sequence so as to be able to analyze a small amount (10 mg) of a glucose derivative (diacetonide glucofuranose, DAGF) with a precision better than 1 mUr at each C-atom position. We also set up a method to correct raw data and express 13C abundance on the usual δ13C scale (δ-scale). In fact, due to the distortion associated with polarization transfer and spin manipulation during 2D-NMR analyses, raw 13C abundance is found to be on an unusual scale. This was compensated for by a correction factor obtained via comparative analysis of a reference material (commercial DAGF) using both previous (single-pulse) and new (2D) sequences. Glucose from different biological origins (CO2assimilation metabolisms of plants, namely, C3, C4, and CAM) was analyzed with the two sequences and compared. Validation criteria such as selectivity, limit of quantification, precision, trueness, and robustness are discussed, including in the framework of green analytical chemistry.

Jusqu'à ces dernières années, les études détaillées des ouvrages hydrauliques étaient réalisées quasiment systématiquement par le biais de modèles physiques. Si l'utilisation de modèles physiques permet de bien appréhender le comportement hydraulique des ouvrages, ils sont en général coûteux, requièrent un temps de mise en œuvre important et ne peuvent représenter que les phénomènes hydrauliques pour lesquels ils ont été définis par similitude. De nos jours, grâce à la puissance de calcul toujours plus grande des ordinateurs et au développement des logiciels spécialisés, la modélisation numérique 3D est devenu un outil flexible et puissant pour accompagner et compléter la modélisation physique, voire même la remplacer dans certains cas. Cet article décrit les apports et enjeux de la modélisation hydraulique 3D pour la conception et la réhabilitation des ouvrages hydrauliques. Il présente, dans un premier temps, comment la modélisation numérique 3D a d'abord été validée sur une large gamme de phénomènes hydrauliques, puis comment elle est exploitée par Tractebel sur plusieurs grands projets, pour analyser et optimiser la conception ou l'exploitation des structures hydrauliques en appui des méthodes analytiques et modèles physiques. Des exemples d'applications complémentaires sont présentés tels que la modélisation de grands évacuateurs de crues, un canal d'amenée, une prise d'eau usinière, ou encore les phénomènes d'entraînement d'air et de dissipation d'énergie dans un ressaut hydraulique ou dans une fosse d'érosion. Les possibilités et les limites de la modélisation 3D sur ces divers sujets sont discutées. Des méthodes de modélisation simplifiées ont été développées pour répondre à des questions spécifiques de manière optimisée. Les procédures élaborées pour chaque cas particulier sont décrites de manière à fournir des processus indicatifs pour le déploiement de la modélisation hydraulique 3D dans des projets d'ingénierie, et ainsi y apporter une valeur ajoutée. En se basant sur l'expérience de Tractebel, les limites et défis qui restent à surmonter sont discutés, avec un accent mis sur la modélisation de l'entraînement d'air.

The isotopic compositions of oxygen (δ18O) and hydrogen (δ2H) are widely used to locate the geographical origin of biological remains or manufactured products. In this paper, we analyse the distributions of δ18O and δ2H in tap waters sampled across France, and in precipitation interpolated with the Online Isotopes in Precipitation Calculator and modelled with the isotope-enabled ECHAM6-wiso model. Our aim is to provide isoscapes usable in archaeology and forensics and evaluate whether the modelled data could be surrogates for measured ones. The δ18O and δ2H in the 396 tap waters sampled varied spatially within a range of 10‰ and 77‰, respectively. Their consistent distributions followed rules summarized by the effects of altitude and distance from the coast. Their variations along the year were small. Therefore, the database provides a solid reference for δ18O and δ2H of the water supply system at the regional scale. The areas with the most uncommon oxygen and hydrogen isotopic compositions (Atlantic coast south of Brittany and the highest elevations in the Alps) are the most accurately traceable areas in provenancing studies. The isotopic compositions of modelled precipitation have the same spatial distributions but different absolute values from those of tap waters. Therefore, our results favour the use of statistical isoscapes rather than general circulation model-based isoscapes in provenancing studies.

δ2H and δ18O values of precipitations follow an empirical linear relationship at the global scale that is called the Global Meteoric Water Line (GMWL) and characterized by a slope of 8. However, Local Meteoric Water Lines (LMWLs) may have different slopes Sdepending on their geographic situation. Monthly δ2H and δ18O of precipitation have been compiled from European International Atomic Energy Agency (IAEA) stations. Those data allowed the calculation of the slopes Sof the δ2H–δ18O LMWL determined for each station. Sincreases with longitude ϕfrom c.5 (Portugal) to c.9 (Russia) – they are positively correlated with relative humidity (RH), negatively with temperature and positively with the mean intra-annual amplitude of temperatures, which is a proxy of continentality. Slopes of 5–6, recorded in SW Europe, reflect mean RH (70–75%) and sea surface temperatures (c.25°C) of the Central Atlantic Ocean where the main flux of moisture is formed before being transported by the westerlies. In addition, falling water droplets within an air column with a high RH (>80%) and low temperature are expected to escape sub-cloud evaporation. Therefore, slopes with values close to 9 are considered to reflect isotopic equilibrium conditions during the condensation of water vapour in clouds.

Jusqu'à ces dernières années, les études détaillées des ouvrages hydrauliques étaient réalisées quasiment systématiquement par le biais de modèles physiques. Si l'utilisation de modèles physiques permet de bien appréhender le comportement hydraulique des ouvrages, ils sont en général coûteux, requièrent un temps de mise en œuvre important et ne peuvent représenter que les phénomènes hydrauliques pour lesquels ils ont été définis par similitude. De nos jours, grâce à la puissance de calcul toujours plus grande des ordinateurs et au développement des logiciels spécialisés, la modélisation numérique 3D est devenu un outil flexible et puissant pour accompagner et compléter la modélisation physique, voire même la remplacer dans certains cas. Cet article décrit les apports et enjeux de la modélisation hydraulique 3D pour la conception et la réhabilitation des ouvrages hydrauliques. Il présente, dans un premier temps, comment la modélisation numérique 3D a d'abord été validée sur une large gamme de phénomènes hydrauliques, puis comment elle est exploitée par Tractebel sur plusieurs grands projets, pour analyser et optimiser la conception ou l'exploitation des structures hydrauliques en appui des méthodes analytiques et modèles physiques. Des exemples d'applications complémentaires sont présentés tels que la modélisation de grands évacuateurs de crues, un canal d'amenée, une prise d'eau usinière, ou encore les phénomènes d'entraînement d'air et de dissipation d'énergie dans un ressaut hydraulique ou dans une fosse d'érosion. Les possibilités et les limites de la modélisation 3D sur ces divers sujets sont discutées. Des méthodes de modélisation simplifiées ont été développées pour répondre à des questions spécifiques de manière optimisée. Les procédures élaborées pour chaque cas particulier sont décrites de manière à fournir des processus indicatifs pour le déploiement de la modélisation hydraulique 3D dans des projets d'ingénierie, et ainsi y apporter une valeur ajoutée. En se basant sur l'expérience de Tractebel, les limites et défis qui restent à surmonter sont discutés, avec un accent mis sur la modélisation de l'entraînement d'air.

Climate reconstructions in temperate Europe have been widely based on oak species. However, other co‐occurring species, largely distributed in Europe, may be used for recording climate variability. In this paper, we documented the intertrees and interspecies variations over 1960–2007 of oxygen and carbon isotopic compositions in ring cellulose of Fagus sylvatica, Pinus sylvestris, and Quercus petraeaco‐occurring in the Fontainebleau forest (France). Our results indicated that large levels of series replication (11 trees on average) were required to generate isotopic mean series representative of the populations. We calculated mean isotopic ratios higher in pine than in the deciduous species and hypothesized that these contrasts resulted from differences in stomatal conductance, phenology, and canopy structure and, for oxygen, also in water uptake depth and isotopic exchange rate. We found that δ18O and δ13C chronologies were significantly correlated to one another in the three species and responded primarily to air moisture and Tmax, which indicated that stomatal conductance was an important driver of changes in both types of records. We determined that the correlations were strong with the May to July climate variables in F. sylvaticaand with the July and August ones in Q. petraeaand P. sylvestris. We showed that the oxygen records were systematically more coherent than those of carbon. This study demonstrated that δ18O, and to a lesser extent δ13C, from the three different species are reliable proxies for reconstructing past hydroclimatic variations in Europe. Carbon and oxygen chronologies in F. sylvatica, P. sylvestris, and Q. petraeaare consistent and strongly correlated with air moisture (VPD) and temperatureA large number of trees (11, on average) is needed to develop robust isotope‐based paleoclimate reconstructionsReconstructions in temperate Europe should concentrate on oxygen isotopic composition

Estimating summer temperature fluctuations over long timescales in southern South America is essential for better understanding the past climate variations in the Southern Hemisphere. Here we developed robust 212 year long basal area increment (BAI) and δ13C chronologies from living temperature‐sensitive Fitzroya cupressoideson the eastern slope of the northern Patagonian Andes (41°S). After removing the increasing trend from the growth records likely due to the CO2fertilization effect, we tested the potential to reconstruct past summer temperature variations using BAI and δ13C as predictors. The reconstruction based on δ13C records has the strongest predictive skills and explains as much as 62% of the total variance in instrumental summer temperature (n= 81, p< 0.001). The temperature signal recorded in tree‐ring growth is not substantially different to that present in δ13C and consequently does not provide additional information to improve the regression models. Our δ13C‐based reconstruction shows cold summer temperatures in the second part of the 19th century and in the mid‐20th century followed by a warmer period. Notably, the 20th and the early 21st centuries were warmer (+0.6°C) than the 19th century. Reconstructed summer temperature variations are modulated by low‐latitude (El Niño–Southern Oscillation) and high‐latitude (Southern Annular Mode) climate forcings. Our reconstruction based on δ13C agrees well with previous ring width based temperature reconstructions in the region and comparatively enhances the low‐frequency variations in the records. The present study provides the first reconstruction of summer temperature in South America south of 40°S for the period 1800–2011 entirely based on isotopic records. The Southern Hemisphere, and particularly southern South America, are very under‐represented in global climate reconstructions due to a lack of robust paleoclimatic data. Here, we reconstruct summer temperature variations on the eastern slope of the Andes in north Patagonia over the last two centuries using tree rings of one of the longest‐living species from South America, Fitzroya cupressoides. This reconstruction highlights that the 20th and 21st centuries were warmer (+ 0.6°C) than the 19th century. Our work thus contributes to improve the assessment of the intensity of current climate changes in remote regions from the Southern Hemisphere. Summer temperatures on the eastern slope of the Northern Patagonian Andes were +0.6°C warmer during the 20th than the 19th centuryThe temperature signal is better recorded in cellulose δ13C values than in tree growth of F. cupressoidesThe recent increase in tree growth on the eastern slope of the Northern Patagonian Andes is likely due to the CO2fertilization effect

The eruption of Samalas in Indonesia in 1257 ranks among the largest sulfur-rich eruptions of the Common Era with sulfur deposition in ice cores reaching twice the volume of the Tambora eruption in 1815. Sedimentological analyses of deposits confirm the exceptional size of the event, which had both an eruption magnitude and a volcanic explosivity index of 7. During the Samalas eruption, more than 40 km3of dense magma was expelled and the eruption column is estimated to have reached altitudes of 43 km. However, the climatic response to the Samalas event is debated since climate model simulations generally predict a stronger and more prolonged surface air cooling of Northern Hemisphere summers than inferred from tree-ring-based temperature reconstructions. Here, we draw on historical archives, ice-core data and tree-ring records to reconstruct the spatial and temporal climate response to the Samalas eruption. We find that 1258 and 1259 experienced some of the coldest Northern Hemisphere summers of the past millennium. However, cooling across the Northern Hemisphere was spatially heterogeneous. Western Europe, Siberia and Japan experienced strong cooling, coinciding with warmer-than-average conditions over Alaska and northern Canada. We suggest that in North America, volcanic radiative forcing was modulated by a positive phase of the El Niño–Southern Oscillation. Contemporary records attest to severe famines in England and Japan, but these began prior to the eruption. We conclude that the Samalas eruption aggravated existing crises, but did not trigger the famines.

Immigration and mobility in the medieval and post-medieval periods in Norway have, up until now, mainly been discussed on the basis of historical sources. This paper presents the results of stable oxygen isotope (δ18O) analyses of the 1st and 3rd molars from 95 individuals from medieval and post-medieval Trondheim, as well as new information about the δ18O composition in the precipitation and drinking water in Trondheim. Through these analyses, the authors have attempted to shed light on the age of migrating individuals and directions of migration, to investigate temporal changes with regard to migration, and to make suggestions regarding the proportion of immigrants to locals in the population.

The Earth’s carbon and hydrologic cycles are intimately coupled by gas exchange through plant stomata. However, uncertainties in the magnitude and consequences of the physiological responses of plants to elevated CO2in natural environments hinders modelling of terrestrial water cycling and carbon storage. Here we use annually resolved long-term δ13C tree-ring measurements across a European forest network to reconstruct the physiologically driven response of intercellular CO2(Ci) caused by atmospheric CO2(Ca) trends. When removing meteorological signals from the δ13C measurements, we find that trees across Europe regulated gas exchange so that for one ppmv atmospheric CO2increase, Ciincreased by ∼0.76 ppmv, most consistent with moderate control towards a constant Ci/Caratio. This response corresponds to twentieth-century intrinsic water-use efficiency (iWUE) increases of 14 ± 10 and 22 ± 6% at broadleaf and coniferous sites, respectively. An ensemble of process-based global vegetation models shows similar CO2effects on iWUE trends. Yet, when operating these models with climate drivers reintroduced, despite decreased stomatal opening, 5% increases in European forest transpiration are calculated over the twentieth century. This counterintuitive result arises from lengthened growing seasons, enhanced evaporative demand in a warming climate, and increased leaf area, which together oppose effects of CO2-induced stomatal closure. Our study questions changes to the hydrological cycle, such as reductions in transpiration and air humidity, hypothesized to result from plant responses to anthropogenic emissions.

Hydroclimate variability in tropical South America is strongly regulated by the South American Summer Monsoon (SASM). However, past precipitation changes are poorly constrained due to limited observations and high‐resolution paleoproxies. We found that summer precipitation and the El Niño‐Southern Oscillation (ENSO) variability are well registered in tree‐ring stable oxygen isotopes (δ18OTR) of Polylepis tarapacanain the Chilean and Bolivian Altiplano in the Central Andes (18–22°S, ∼4,500 m a.s.l.) with the northern forests having the strongest climate signal. More enriched δ18OTRvalues were found at the southern sites likely due to the increasing aridity toward the southwest of the Altiplano. The climate signal of P. tarapacana δ18OTRis the combined result of moisture transported from the Amazon Basin, modulated by the SASM, ENSO, and local evaporation, and emerges as a novel tree‐ring climate proxy for the southern tropical Andes. Understanding past climatic changes in the Central Andes in tropical South America is of great importance to contextualize current hydroclimatic conditions. Here, we present the first P. tarapacanatree‐ring stable oxygen isotope (δ18OTR) chronologies and analyze their value as environmental records for this region. Locally known as queñoa, P. tarapacanagrows in the South American Altiplano from 16°S to 23°S at very high elevations (up to 5,100 m a.s.l), making it the highest elevation tree species worldwide. We analyze P. tarapacana δ18OTRfrom 1950 to present and find that it registers precipitation changes in the Altiplano and the El Niño ‐ Southern Oscillation (ENSO). We suggest that δ18OTRis likely affected by soil evaporation and leaf transpiration due to the high solar radiation and aridity in the Altiplano, leading to an enrichment in δ18OTRvalues with a more pronounced effect at the more arid sites. P. tarapacana δ18OTRreflects the atmospheric processes transporting moisture to the Altiplano and the influence of local evaporation. Our findings are relevant for generating robust hydroclimate reconstructions in the Central Andes to improve circulation models and provide better management of water resources in tropical South America. Tree‐ring stable oxygen isotopes of Polylepis tarapacanarecord austral summer precipitation variability in the South American AltiplanoEl Niño‐Southern Oscillation is imprinted in the tree‐ring oxygen isotopes with a stronger signal toward the north of the studied area Tree‐ring stable oxygen isotopes of Polylepis tarapacanarecord austral summer precipitation variability in the South American Altiplano El Niño‐Southern Oscillation is imprinted in the tree‐ring oxygen isotopes with a stronger signal toward the north of the studied area

A high‐precision, and rapid on‐line method for oxygen isotope analysis of silver phosphate is presented. The technique uses high‐temperature elemental analyzer (EA)‐pyrolysis interfaced in continuous flow (CF) mode to an isotopic ratio mass spectrometer (IRMS). Calibration curves were generated by synthesizing silver phosphate with a 13‰ spread in δ18O values. Calibration materials were obtained by reacting dissolved potassium dihydrogen phosphate (KH2PO4) with water samples of various oxygen isotope compositions at 373 K. Validity of the method was tested by comparing the on‐line results with those obtained by classical off‐line sample preparation and dual inlet isotope measurement. In addition, silver phosphate precipitates were prepared from a collection of biogenic apatites with known δ18O values ranging from 12.8 to 29.9‰ (V–SMOW). Reproducibility of ± 0.2‰ was obtained by the EA‐Py‐CF‐IRMS method for sample sizes in the range 400–500 µg. Both natural and synthetic samples are remarkably well correlated with conventional 18O/16O determinations. Silver phosphate is a very stable material and easy to degas and, thus, could be considered as a good candidate to become a reference material for the determination of 18O/16O ratios of phosphate by high‐temperature pyrolysis. Copyright © 2006 John Wiley & Sons, Ltd.

The three-dimensional structure of the antigen-binding fragment of a monoclonal antibody to human interleukin-2 in a new crystal form (space group P212121; unit cell parameters: a= 42.82 Å, b= 90.68 Å, and c= 139.82 Å) was determined by the X-ray molecular replacement method at the resolution of 2.7 Å. The protein folding and the stereochemistry of its antigen-binding site were comparatively analyzed.

Extensions of a new technique for the finite element modelling of cracks with multiple branches, multiple holes and cracks emanating from holes are presented. This extended finite element method (X-FEM) allows the representation of crack discontinuities and voids independently of the mesh. A standard displacement-based approximation is enriched by incorporating discontinuous fields through a partition of unity method. A methodology that constructs the enriched approximation based on the interaction of the discontinuous geometric features with the mesh is developed. Computation of the stress intensity factors (SIF) in different examples involving branched and intersecting cracks as well as cracks emanating from holes are presented to demonstrate the accuracy and the robustness of the proposed technique. Copyright © 2000 John Wiley & Sons, Ltd.

The rare earth elements (REE) were analysed in the interstitial fluids, in the basalts and in the alteration products (clays and zeolites) of Mururoa atoll volcanic rocks (French Polynesia) in order to investigate REE behaviour during seawater/basalt interactions at low temperature. The REE distribution coefficients between fluids and secondary products were calculated using the EQ3/6 geochemical code. The reversible/irreversible character of the REE entrapment in secondary products was tested. The REE concentrations in the clays are close to that of basalt. The concentrations in zeolites are 10 times lower. Comparison of measured and modeled concentrations in solutions favours the irreversible incorporation assumption. The affinity of the REE for the secondary products is shown to be high. The calculated distribution coefficients range from 3×105for Lu and Eu to 107for Ce in clays and from 104to 7×105in zeolites. The distribution coefficients exhibit a progressive decrease from La to Lu. This behaviour is related to the greater stability of HREE complexes relative to LREE complexes in solution. Under reducing conditions in the interstitial fluids (Eh down to −500 mV), Eu undergoes reduction to the mobile Eu(II). This enhanced mobility is reflected by Eu distribution coefficient being lower than those of adjacent REE. The distribution coefficient of Ce is higher. As Ce is trivalent in the fluids, fractionation from the other trivalent REE was unexpected. The calculated distribution coefficients of REE are lower in zeolites than in clays and this can be related to the spatial distribution and paragenesis of the secondary phases: the dissolution of the basalt promotes the precipitation of clays at the basalt–fluid interface and of zeolites in the bulk solution. The REE released by dissolution are incorporated into the clays and further uptake occurs in zeolites for the REE left in solution.

Modeling work of the isotopic composition of tree ring cellulose (δ18Ocell) relies on the isotopic equilibrium assumption between atmospheric water vapor and tree source water, frequently assimilated to integrated precipitation. Here, we explore the veracity of this assumption based on observations collected during a field campaign in Río Negro province (Argentina) in February–March 2017. We examine how the observed isotopic composition of water vapor deviates from equilibrium with precipitation. This deviation, named isotopic disequilibrium (Δ18Ovap_eq), is low (between −2.0‰ and 4.1‰) and a significant relationship is observed between the isotopic composition of water vapor and its expected value at equilibrium. Negative Δ18Ovap_eqcan be explained by evaporation of small raindrops (from 1% to 5% of initial droplet mass). Positive Δ18Ovap_eqcan result from vegetation transpiration with transpired water accounting for 14% to 29% to ambient water vapor. The low Δ18Ovap_eqat the study site may be due to the high level of relative humidity (from 70% to 96%) favoring isotopic diffusive exchanges between the two water phases and thus promoting the isotopic equilibrium. We examine the impact of the isotopic equilibrium assumption on the calculation of δ18Ocell. A perfect agreement is shown between observed and calculated δ18Ocellprovided that the isotopic composition of source water is significantly higher than the expected averaged isotopic composition of precipitation over the tree growing period. Each individual rain event deviates from the isotopic equilibrium state with water vaporA significant correlation is shown between water vapor isotopic ratios and their expected values at equilibrium with rain over 2 weeksA perfect agreement between observed and calculated cellulose isotopic ratio is found when considering the vapor‐rain isotopic equilibrium