A first inventory of the labile biochemicals found in Avignon groundwater: can we identify potential bacterial substrates?

Groundwater is a major source of water for irrigation of vegetables, especially in the Mediterranean basin. Contamination of aquifer by pathogens has been responsible for numerous disease outbreaks worldwide. Several studies reported that groundwater dissolved organic matter (DOM) can serve as a source of carbon and energy for heterotrophic metabolism of pathogens. In this study, we aimed to investigate the DOM composition of groundwater collected at Avignon. Six liters of groundwater were filtered (0.2 µm) and freeze-dried following appropriate cleaning procedure. The bulk analyses of powder sample were performed using 1D and 2D nuclear magnetic resonance spectroscopy and liquid chromatography coupled with mass spectroscopy. Several components were found at concentrations around 1 µM and comprise: (i) humic and fulvic acids originated from land-derived material or soils and, (ii) various acids, esters and alcohols of different sizes including acetate, lactate and formate, these may result from microbial metabolism. In conclusion, the Avignon groundwater DOM contains a heterogeneous mixture of dissolved organic components with a rather low potential bioreactivity based on the low level of labile biogeochemicals such as carbohydrates

A chemical survey of exoplanets with ARIEL

Thousands of exoplanets have now been discovered with a huge range of masses, sizes and orbits: from rocky Earth-like planets to large gas giants grazing the surface of their host star. However, the essential nature of these exoplanets remains largely mysterious: there is no known, discernible pattern linking the presence, size, or orbital parameters of a planet to the nature of its parent star. We have little idea whether the chemistry of a planet is linked to its formation environment, or whether the type of host star drives the physics and chemistry of the planet’s birth, and evolution. ARIEL was conceived to observe a large number (~1000) of transiting planets for statistical understanding, including gas giants, Neptunes, super-Earths and Earth-size planets around a range of host star types using transit spectroscopy in the 1.25–7.8 μm spectral range and multiple narrow-band photometry in the optical. ARIEL will focus on warm and hot planets to take advantage of their well-mixed atmospheres which should show minimal condensation and sequestration of high-Z materials compared to their colder Solar System siblings. Said warm and hot atmospheres are expected to be more representative of the planetary bulk composition. Observations of these warm/hot exoplanets, and in particular of their elemental composition (especially C, O, N, S, Si), will allow the understanding of the early stages of planetary and atmospheric formation during the nebular phase and the following few million years. ARIEL will thus provide a representative picture of the chemical nature of the exoplanets and relate this directly to the type and chemical environment of the host star. ARIEL is designed as a dedicated survey mission for combined-light spectroscopy, capable of observing a large and well-defined planet sample within its 4-year mission lifetime. Transit, eclipse and phase-curve spectroscopy methods, whereby the signal from the star and planet are differentiated using knowledge of the planetary ephemerides, allow us to measure atmospheric signals from the planet at levels of 10–100 part per million (ppm) relative to the star and, given the bright nature of targets, also allows more sophisticated techniques, such as eclipse mapping, to give a deeper insight into the nature of the atmosphere. These types of observations require a stable payload and satellite platform with broad, instantaneous wavelength coverage to detect many molecular species, probe the thermal structure, identify clouds and monitor the stellar activity. The wavelength range proposed covers all the expected major atmospheric gases from e.g. H2O, CO2, CH4 NH3, HCN, H2S through to the more exotic metallic compounds, such as TiO, VO, and condensed species. Simulations of ARIEL performance in conducting exoplanet surveys have been performed – using conservative estimates of mission performance and a full model of all significant noise sources in the measurement – using a list of potential ARIEL targets that incorporates the latest available exoplanet statistics. The conclusion at the end of the Phase A study, is that ARIEL – in line with the stated mission objectives – will be able to observe about 1000 exoplanets depending on the details of the adopted survey strategy, thus confirming the feasibility of the main science objectives.Peer reviewedFinal Published versio

Cesarean delivery on maternal request: Can the ethical problem be solved by the principlist approach?

In this article, we use the principlist approach to identify, analyse and attempt to solve the ethical problem raised by a pregnant woman's request for cesarean delivery in absence of medical indications

ECMO for COVID-19 patients in Europe and Israel

Since March 15th, 2020, 177 centres from Europe and Israel have joined the study, routinely reporting on the ECMO support they provide to COVID-19 patients. The mean annual number of cases treated with ECMO in the participating centres before the pandemic (2019) was 55. The number of COVID-19 patients has increased rapidly each week reaching 1531 treated patients as of September 14th. The greatest number of cases has been reported from France (n = 385), UK (n = 193), Germany (n = 176), Spain (n = 166), and Italy (n = 136) .The mean age of treated patients was 52.6 years (range 16–80), 79% were male. The ECMO configuration used was VV in 91% of cases, VA in 5% and other in 4%. The mean PaO2 before ECMO implantation was 65 mmHg. The mean duration of ECMO support thus far has been 18 days and the mean ICU length of stay of these patients was 33 days. As of the 14th September, overall 841 patients have been weaned from ECMO support, 601 died during ECMO support, 71 died after withdrawal of ECMO, 79 are still receiving ECMO support and for 10 patients status n.a. . Our preliminary data suggest that patients placed on ECMO with severe refractory respiratory or cardiac failure secondary to COVID-19 have a reasonable (55%) chance of survival. Further extensive data analysis is expected to provide invaluable information on the demographics, severity of illness, indications and different ECMO management strategies in these patients

Etude des modes d'acquisition de la signature isotopique en carbone des eaux souterraines et préservation du signal environnemental lors de la recharge des aquifères

La gestion des ressources en eau souterraine consiste en partie à l estimation du temps de séjour de l eau dans l aquifère. La décroissance radioactive du 14C au cours du temps est une méthode couramment utilisée. Cependant, elle repose notamment sur l estimation de l activité 14C (A14C) initiale des eaux souterraines. L eau se minéralise en carbone lors de son transfert à travers la zone non saturée (ZNS) par interaction avec le CO2 et la matrice carbonatée, interactions qui font l objet de cette étude. Un équipement spécifique au prélèvement du gaz, de l eau et de la matrice a été mis en place sur deux sites d étude en France, les sables de Fontainebleau non carbonatés (Yvelines) et les sables astiens carbonatés (Hérault). Les mesures in-situ sont couplées à une approche numérique afin de mieux contraindre les différents facteurs à l origine de la composition isotopique du CO2 à la base de la ZNS. En l absence de carbonates, le 13C du CO2 dépend du 13C moyen du CO2 produit, des quantités de CO2 produit et du coefficient de diffusion du CO2. Les variations saisonnières du 13C du CO2 en sub-surface tendent à disparaître en profondeur. Avant 1950, l A14C du CO2 peut être considérée égale à celle du CO2 atmosphérique. Après 1950, suite aux essais nucléaires atmosphériques, elle est intermédiaire entre celle du CO2 atmosphérique et celle de la matière organique à taux de renouvellement rapide. En présence de carbonates, le 13C du CO2 augmente (l A14C diminue) avec la profondeur. Cette évolution dépend du flux de précipitation/dissolution des carbonates, des quantités de CO2 produit et du coefficient de diffusion du CO2 dans la ZNS.The management of groundwater needs the estimation of the water residence time in aquifers, that can be done through the measurement of 14C radioactive decay of the Total Dissolved Inorganic Carbon (TDIC). This approach requires the knowledge of the TDIC 14C initial activity in recharge water. The groundwater mineralisation occurs in the Unsaturated Zone (UZ), where water interacts with CO2 and carbonates (if existing). We focus here on these interactions between both CO2, TDIC and carbonates. Two UZ have been investigated in France: the carbonate-free Fontainebleau sands and the carbonated Astian sands. Each site is equipped with a specific and experimental equipment to collect groundwater, UZ water, gas and solid matrix (organic matter and carbonate). The field-data are completed by a numeric approach in order to evaluate the different factors that define the CO2 isotopic composition at the bottom of the UZ. The 13C of CO2 depends on the mean 13C of produced CO2, the amount of produced CO2 and the diffusion coefficient of CO2. Subsurface seasonal variations of 13C disappear with depth. Before 1950, the 14C activity of CO2 can be assumed equal to atmospheric 14C level. After 1950, due to the atmospheric nuclear test, it depends on 14C activity of young organic matter and atmospheric CO2. The presence of carbonates leads to a 13C-enrichment of and a 14C-depletion of CO2 with depth, depending on the carbonate precipitation/dissolution flux, the amount of produced CO2 and the diffusion coefficient of CO2.ORSAY-PARIS 11-BU Sciences (914712101) / SudocSudocFranceF

Kinetics of incongruent dissolution of carbonates in a Chalk aquifer using reverse flow modelling

International audiences u m m a r y Water–rock interactions are major processes that control the solute transfer (from natural or anthropo-genic sources) in aquifers. In carbonate aquifers, these water–rock interactions are mainly characterised by the incongruent dissolutions of carbonates. The in situ quantification of these reactions is few studied. In the present paper, we provide a new quantification of the kinetic rates of simultaneous incongruent dissolution of composite carbonate and dolomite in a Chalk aquifer. The approach is based on a mass-balance model used to calculate the rates of mineral dissolution and precipitation along a 500 m to 4 km flow path starting at the groundwater divide line. The groundwater transfer times between the groundwater divide line and the wells are calculated thanks to flow and transport modelling, used in a backward particle tracking mode. The uncertainties on porosity, dispersivity and transmissivity are taken into account. The rates are found ranging between 1.5 Â 10 À5 and 1.5 Â 10 À4 mol C5 chalk L À1 w yr À1 for the composite carbonate dissolution, between 1.0 Â 10 À7 and 3.0 Â 10 À6 mol dolomite L À1 w yr À1 for the dolomite dissolution and between 1.0 Â 10 À5 and 1.5 Â 10 À4 mol calcite L À1 w yr À1 for the calcite precipitation. The results highlight the importance of physical and geological properties of the aquifer

Controls on 13C and 14C variability in soil CO2

International audience14C dating of groundwater depends on the isotopic composition of both the solid carbonate and the soil CO2 and requires the use of 14C age correction models. To better assess the variability of the 14C activity of soil CO2 (A14Csoil-CO2) and the δ13C of soil CO2 (δ13Csoil-CO2), which are two parameters used in 14C age correction models, we studied the different processes involving carbon isotopes in the soil. The approach used experimental data from two sites in France (Fontainebleau sands and Astian sands) and a steady-state transport model. In most cases, the 14C activity (A14C) of atmospheric CO2 is directly used in the 14C age correction models as the A14Csoil-CO2. However, we demonstrate that since 1950, the evolution of the A14Csoil-CO2 reflects the competition between the fluxes of root-derived CO2 and organic matter-derived CO2. Therefore, the A14Csoil-CO2 must be used to date groundwater that is younger than 60 years old. Moreover, the δ13C of soil CO2 (δ13Csoil-CO2) showed large seasonal variations that must be taken into account in selecting the δ13Csoil-CO2 for 14C age correction models

« Combining 3H, 14C, and lumped parameter models to characterize modern groundwater residence time in a highly anthropized watershed ».

International audienc

Origin of δ13C-CO2 and A14C-CO2 variability in soil.

International audienc