How warm was Greenland during the last interglacial period?

The last interglacial period (LIG, ~ 129–116 thousand years ago) provides the most recent case study for multi-millennial polar warming above pre-industrial level and a respective response of the Greenland and Antarctic ice sheets to this warming, as well as a test bed for climate and ice sheet models. Past changes in Greenland ice sheet thickness and surface temperature during this period were recently derived from the NEEM ice core records, North-West Greenland. The NEEM paradox has emerged from an estimated large local warming above pre-industrial level (7.5 ± 1.8 °C at the deposition site 126 ka ago without correction for any overall ice sheet altitude changes between the LIG and pre-industrial) based on water isotopes, together with limited local ice thinning, suggesting more resilience of the real Greenland ice sheet than shown in some ice sheet models. Here, we provide an independent assessment of the average LIG Greenland surface warming using ice core air isotopic composition (δ15N) and relationships between accumulation rate and temperature. The LIG surface temperature at the upstream NEEM deposition site without ice sheet altitude correction is estimated to be warmer by +7 to +11 °C (+8 °C being the most likely estimate according to constraints on past accumulation rate) compared to the pre-industrial period. This temperature estimate is consistent with the 7.5 ± 1.8 °C warming initially determined from NEEM water isotopes. Moreover, we show that under such warm temperatures, melting of snow probably led to a significant firn shrinking by ~ 15 m. Climate simulations performed with present day ice sheet topography lead to much smaller warming but larger amplitudes (up to 5 °C) can be obtained from changes in sea ice extent and ice sheet topography. Still, ice sheet simulations forced by 5 °C surface warming lead to large ice sheet decay that are not compatible with existing data. Our new, independent temperature constrain therefore reinforces the NEEM paradox

Clinical and molecular characterization of 17q21.31 microdeletion syndrome in 14 French patients with mental retardation.

International audienceChromosome 17q21.31 microdeletion was one of the first genomic disorders identified by chromosome microarrays. We report here the clinical and molecular characterization of a new series of 14 French patients with this microdeletion syndrome. The most frequent clinical features were hypotonia, developmental delay and facial dysmorphism, but scaphocephaly, prenatal ischemic infarction and perception deafness were also described. Genotyping of the parents showed that the parent from which the abnormality was inherited carried the H2 inversion polymorphism, confirming that the H2 allele is necessary, but not sufficient to generate the 17q21.31 microdeletion. Previously reported molecular analyses of patients with 17q21.31 microdeletion syndrome defined a 493 kb genomic fragment that was deleted in most patients after taking into account frequent copy number variations in normal controls, but the deleted interval was significantly smaller (205 kb) in one of our patients, encompassing only the MAPT, STH and KIAA1267 genes. As this patient presents the classical phenotype of 17q21.31 syndrome, these data make it possible to define a new minimal critical region of 160.8 kb, strengthening the evidence for involvement of the MAPT gene in this syndrome

The DEEPICE research and training network

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Composition organique de boues résiduaires de stations d'épuration lorraines (caractérisation moléculaire et effets de la biodégradation)

Cette étude s'est intéressée à la caractérisation moléculaire du contenu organique de boues résiduaires de stations d'épuration de la région Lorraine. Les quarante huit échantillons collectés proviennent de stations domestiques de différentes tailles (rurales, petites urbaines et urbaines), de stations industrielles (papeteries) et de stations agro-alimentaires (laiteries et fromageries). Le premier volet développé au cours de cette étude a permis de dresser l'inventaire des composés présents dans les boues d'épuration (i) sous forme libre (fraction organique soluble- FOS) et (ii) sous forme liée à la structure macromoléculaire (fraction organique insoluble- FOI). A cette fin, les outils analytiques respectivement utilisés sont la GC-MS d'une part, et la THM-GC-MS et Py-GC-AED d'autre part. Les résultats de l'analyse de la FOS et de la FOI fournissent une information équivalente dans la mesure où ils permettent de différencier les boues selon leur origine (agro-alimentaire, industrielle ou domestique). Une empreinte moléculaire spécifique à chaque type de boues a ainsi pu être définie. Par ailleurs, l'ensemble des boues domestiques est caractérisé par un fonds géochimique pétrolier, témoignant d'une pollution diffuse commune. Une variabilité autour de ce fonds géochimique a également pu être identifiée pour certaines boues domestiques, sans relation avec la taille de la station, ni le degré d'industrialisation de la région. Ces variations, essentiellement observées au niveau de la FOS, peuvent par contre être imputées à des pollutions ponctuelles ou accidentelles dans le système de collecte des eaux usées domestiques. Ce travail a pour but de fournir, à terme, des paramètres moléculaires d'aide au suivi et au contrôle des réseaux de collecte des eaux usées. Le deuxième volet de ce projet s'est intéressé à l'étude des effets de la biodégradation sur le contenu organique des boues. Afin de simuler les processus de dégradation, quatre échantllions ont été incubés à 24C pendant 140 jours. L'analyse couplée de la FOS et de la FOI des échantillons biodégradés a permis de déterminer les grandes tendances de l'évolution du contenu organique au cours des expérimentations. Un schéma réactionnel global de biodégradation peut ainsi être proposé: l'altération de la structure macromoléculaire de la FOI libère des composés extractibles, dégradés eux-mêmes en composés de plus bas poids moléculaire ou minéralisés. Par ailleurs, cette étude a permis de déterminer des indices de biodégradation ainsi que des marqueurs organiques résistants à cette biodégradation.This study deals with the molecular characterisation of the organic content of sewage sludges from Lorraine (Northeast of France). The 48 samples collected come from domestic wastewater treatment plant of different capacities (rural, small urban and urban) and from depuration stations treating dairy, cheese dairy and paper-mill effluents. The first part of this study enabled to make the inventory of the compound present in sewage sludges (1) under free form (soluble organic fraction - SOF), and (ii) Iinked to the macromolecular structure (insoluble organic fraction - lOF). To achieve that, the analytical tools used were respectively GC-MS on the one hand, and THM-GC-MS and Py-GC-AED on the other hand. The results of the analysis of the SOF and lOF provide equivalent information ln that they enable the differentiation of siudges according to thelr origin (food-processing, paper-mlli or domestic). A molecular fingerprint specific to each type of sludge was thus defined. Besides, all the domestic sludges are characterised by a geochemical petroleum background which testifies to a common diffuse pollution. Moreover, a variability in this geochemical background was observed for some domestic sludges, regardless of the size of the station, or of the degree of industrialisation of the region. These variations, which are essentially observed in the SOF, can be attributed to punctual or accidental pollution in the sewer system of domestic wastewater. The eventual goal of this work ls to provide molecular parameters in order to improve the monitoring and the control of wastewater sewer systems. The second part of this project studies the effects of biodegradation on the organic content of sewage sludges. Four samples were incubated at 24C during 140 days in order to simulate the processes of degradation. The simultaneous analysis of the SOF and lOF of the biodegraded samples enabled the determination of the great tendencies of the evolution of the organic content during the experiments. A global pattern of biodegradation reactions can thus be proposed: the chemical degradation of the macromolecular structure of the lOF produces extractable compounds which will be either degraded themselves into lower molecular weight compounds or mineralised. Besides, organic markers resistant to biodegradation couId be determined and indexes of biodegradation proposed.NANCY1-SCD Sciences & Techniques (545782101) / SudocSudocFranceF

Icechrono1 : un modèle probabiliste pour calculer une chronologie commune et optimale pour plusieurs carottes de glace

International audiencePolar ice cores provide exceptional archives of past environmental conditions. The dating of ice cores and the estimation of the age-scale uncertainty are essential to interpret the climate and environmental records that they contain. It is, however, a complex problem which involves different methods. Here, we present IceChrono1, a new probabilistic model integrating various sources of chronological information to produce a common and optimized chronology for several ice cores, as well as its uncertainty. IceChrono1 is based on the inference of three quantities: the surface accumulation rate, the lock-in depth (LID) of air bubbles and the thinning function. The chronological information integrated into IceChrono1 are modeling scenarios of the sedimentation process (accumulation of snow, densification of snow into ice and air trapping, ice flow), ice-and air-dated horizons, ice and air depth intervals with known durations, Δdepth observations (depth shift between synchronous events recorded in the ice and in the air) and finally ice, air or mix stratigraphic links in between ice cores. the inference problem is formulated as a least squares optimisation, implying that all densities of probabilities are assumed to be Gaussian. It is numerically solved using the Levenberg-Marquardt algorithm (thus assuming that the model is almost linear in the vicinity of the solution) and a numerical evaluation of the model's Jacobian. IceChrono1 is freely available under the General Public License v3 open source license.Les forages polaires fournissent des archives exceptionnelles des conditions climatiques et environnementales passées. Produire une datation robuste des carottes de glace ainsi qu'une estimation de l'incertitude associée est essentiel pour interpréter les enregistrements climatiques et environnementaux qu'elles contiennent. Cependant, c'est une tâche complexe car elle implique d'utiliser différentes méthodes. Dans cet article, nous présentons IceChrono1, un modèle probabiliste qui combine différentes sources d'information chronologique pour produire une datation commune et optimale pour plusieurs carottes de glace, ainsi qu'une estimation de l'incertitude associée. IceChrono1 est basé sur l'inférence de trois quantités : le taux d'accumulation de neige en surface, la profondeur de piégeage de l'air et la fonction d'amincissement. IceChrono1 intègre de multiples informations chronologiques : un scénario modélisé du processus de sédimentation (accumulation de la neige, densification de la neige en glace et piégeage de l'air, écoulement de la glace), des horizons bien datés pour contraindre l'âge de la glace ou l'âge de l'air, des intervalles de profon-deur définis sur la glace ou via des mesures sur l'air piégé dont la durée est connue, des observations du Δprofondeur (le décalage en profondeur entre des événements synchrones enregistrés dans la glace et dans l'air) et finalement des liens stratigraphiques reliant des marqueurs identifiés dans la glace, dans l'air piégé ou dans les deux à la fois entre les carottes de glace. L'inférence est formulée comme un problème d'optimisation aux moindres carrés, impliquant que toutes les densités de probabilités sont supposées gaussiennes. Elle est résolue numériquement en utilisant l'algorithme de Levenberg-Marquardt (supposant ainsi que le modèle est presque linéaire au voisinage de la solution) et une évaluation numérique du Jacobien du modèle. IceChrono1 est librement disponible sous la licence libre GPL v3 (General Public License v3)

Application of thermodesorption and pyrolysis-GC–AED to the analysis of river sediments and sewage sludges for environmental purpose

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Compound-specific δ 18O of triterpenols: rationale, first results and issues

International audienceThe D18OLE project aimsat developing the determination of δ18O values of triterpenols in order to reconstruct pastatmospheric O2(O2atm) δ18O values and evaluate changes in the Dole Effect over the Cenozoic. Cultivation of Panicum miliaceumwith varying H2O and CO2δ18O valuesshowed that oxygen in miliacin, a C3-oxygenated pentacyclic triterpene,derives from respired O2, in agreement with biogeochemical observationsand consistant with modeled isotope fractionation factor. δ18O values of triterpenols preserved in the fossil record should thus allow estimating the long-term evolution of O2atmδ18O values.The first challenge consists in affordinga robust determination of sterols and triterpenols δ18O values by GC-Py-irMS. The low O/C ratio for these compounds constitutes an analytical challenge. First results acquired on miliacin and friedelin display large peaks by gas chromatography, preventingacceptable reproducibility. A second issue is the current lack of international lipids standards with known δ18O values.The fractionation factor between O2atmand O in triterpenols will be determinedby cultivating vascular plants and algae under controlled atmosphere with known O2δ18O values. Finally, δ18O values of triterpenols will be determined in a set of lignites and lacustrinesediments that cover two major climatic crisis of the Cenozoic : the Paleocene-Eocene Thermal Maximum and the Eocene/Oligcene boundary

IceChrono1: a probabilistic model to compute a common and optimal chronology for several ice cores

International audiencePolar ice cores provide exceptional archives of past environmental conditions. The dating of ice cores and the estimation of the age-scale uncertainty are essential to interpret the climate and environmental records that they contain. It is, however, a complex problem which involves different methods. Here, we present IceChrono1, a new probabilistic model integrating various sources of chronological information to produce a common and optimized chronology for several ice cores, as well as its uncertainty. IceChrono1 is based on the inversion of three quantities: the surface accumulation rate, the lock-in depth (LID) of air bubbles and the thinning function. The chronological information integrated into the model are models of the sedimentation process (accumulation of snow, densification of snow into ice and air trapping, ice flow), ice- and air-dated horizons, ice and air depth intervals with known durations, Δdepth observations (depth shift between synchronous events recorded in the ice and in the air) and finally air and ice stratigraphic links in between ice cores. The optimization is formulated as a least squares problem, implying that all densities of probabilities are assumed to be Gaussian. It is numerically solved using the Levenberg–Marquardt algorithm and a numerical evaluation of the model's Jacobian. IceChrono follows an approach similar to that of the Datice model which was recently used to produce the AICC2012 (Antarctic ice core chronology) for four Antarctic ice cores and one Greenland ice core. IceChrono1 provides improvements and simplifications with respect to Datice from the mathematical, numerical and programming point of views. The capabilities of IceChrono1 are demonstrated on a case study similar to the AICC2012 dating experiment. We find results similar to those of Datice, within a few centuries, which is a confirmation of both IceChrono1 and Datice codes. We also test new functionalities with respect to the original version of Datice: observations as ice intervals with known durations, correlated observations, observations as air intervals with known durations and observations as mixed ice–air stratigraphic links. IceChrono1 is freely available under the General Public License v3 open source license