The status of the energy calibration, polarization and monochromatization of the FCC-ee

The Future Circular electron-positron Collider, FCC- ee, is designed for unprecedented precision for particle physics experiments from the Z-pole up to above the top-pair-threshold, corresponding to a beam energy range from 45.6 to 182.5 GeV. Performing collisions at various particle-physics resonances requires precise knowledge of the centre-of-mass energy (ECM) and collision boosts at all four interaction points. Measurement of the ECM by resonant depolarization of transversely polarized pilot bunches in combination with a 3D polarimeter, aims to achieve a systematic uncertainty of 4 and 100 keV for the Z-pole and W-pair-threshold energies respectively. The ECM itself depends on the RF-cavity locations, beamstrahlung, longitudinal impedance, the Earth’s tides, opposite sign dispersion and possible collision offsets. Application of monochromatization schemes are envisaged at certain beam energies to reduce the energy spread. The latest results of studies of the energy calibration, polarization and monochromatization are reported here

The Biodiversity of the Mediterranean Sea: Estimates, Patterns, and Threats

The Mediterranean Sea is a marine biodiversity hot spot. Here we combined an extensive literature analysis with expert opinions to update publicly available estimates of major taxa in this marine ecosystem and to revise and update several species lists. We also assessed overall spatial and temporal patterns of species diversity and identified major changes and threats. Our results listed approximately 17,000 marine species occurring in the Mediterranean Sea. However, our estimates of marine diversity are still incomplete as yet—undescribed species will be added in the future. Diversity for microbes is substantially underestimated, and the deep-sea areas and portions of the southern and eastern region are still poorly known. In addition, the invasion of alien species is a crucial factor that will continue to change the biodiversity of the Mediterranean, mainly in its eastern basin that can spread rapidly northwards and westwards due to the warming of the Mediterranean Sea. Spatial patterns showed a general decrease in biodiversity from northwestern to southeastern regions following a gradient of production, with some exceptions and caution due to gaps in our knowledge of the biota along the southern and eastern rims. Biodiversity was also generally higher in coastal areas and continental shelves, and decreases with depth. Temporal trends indicated that overexploitation and habitat loss have been the main human drivers of historical changes in biodiversity. At present, habitat loss and degradation, followed by fishing impacts, pollution, climate change, eutrophication, and the establishment of alien species are the most important threats and affect the greatest number of taxonomic groups. All these impacts are expected to grow in importance in the future, especially climate change and habitat degradation. The spatial identification of hot spots highlighted the ecological importance of most of the western Mediterranean shelves (and in particular, the Strait of Gibraltar and the adjacent Alboran Sea), western African coast, the Adriatic, and the Aegean Sea, which show high concentrations of endangered, threatened, or vulnerable species. The Levantine Basin, severely impacted by the invasion of species, is endangered as well

Réunion

Blondel Thibaut. Réunion. In: Karstologia : revue de karstologie et de spéléologie physique, n°54, 2e semestre 2009. La grotte de Kanaan (Liban) et Géomorphosites karstiques. pp. 56-57

Réunion

Blondel Thibaut. Réunion. In: Karstologia : revue de karstologie et de spéléologie physique, n°54, 2e semestre 2009. La grotte de Kanaan (Liban) et Géomorphosites karstiques. pp. 56-57

Traçage spatial et temporel des eaux souterraines dans les hydrosystèmes karstiques par les matières organiques dissoutes : expérimentation et application sur les sites du Laboratoire Souterrain à Bas Bruit (LSBB) de Rustrel – Pays d’Apt et de Fontaine de Vaucluse

Diplôme : Diplôme de Recherche UniversitaireThe aim of this study is to develop, apply and validate new hydrogeological tracers, based on specific spectral fingerprints of Dissolved Organic Matter (DOM), and a monitoring of their evolution in Mediterranean karstic hydrosystems. Many hydrodynamic and hydrochemical analyses were made, and several DOM characterization methods were used. The basis of this work is therefore the study of different levels of Fontaine de Vaucluse experimental basin (soil, epikarst and unsaturated zone), thanks to a privileged access : the Low-Noise Underground Laboratory of Rustrel - Pays d’Apt (Vaucluse, France). Good hydrogeological tracers require specific characteristics (water solubility, stability, a low tendency to adsorption, a low detection limit and identifiable variations). Organic compounds, corresponding to these criterions at best, are lignin-derived compounds. Their different characteristics and their low concentrations in the hydrosystem drive us to use sensitive enough detection methods, such as fluorescence spectrometry and Electronic Paramagnetic Resonance (EPR). Linked application of EPR and spectrofluorimetric analyses of leachate soil and LSBB groundwater allow to develop two hydrogeological tracing protocols. The first one concerns the determination of upper soil zone, which belongs to monitoring flow catchment area. The second one, using the evolution and the dynamics of DOM in the hydrosystem, corresponds to the development of transit time qualitative tracers, which apply either in an event-driven way by the marking of specific period of their variations, or continuously allowing the monitoring of transit time variations. Finally, the comparison between the results obtained by these new organic tracers and by an isotopic tracer (18 Oxygen) allows to validate transit time calculations and prove their complementarityLe principal objectif de ce travail est le développement, l'application et la validation de nouveaux traceurs hydrogéologiques sur la base de signatures spectrales spécifiques des matières organiques dissoutes (MOD) et du suivi de leur évolution dans les hydrosystèmes karstiques méditerranéens. Pour cela, de nombreuses analyses hydrodynamiques et hydrochimiques ont été réalisées, et plusieurs méthodes de caractérisation de la MOD ont été utilisées. Le travail s'est alors fondé sur l'étude de différents niveaux du bassin expérimental de la Fontaine de Vaucluse (sol, épikarst et zone non saturée), grâce à un accès privilégié rendu possible par le Laboratoire Souterrain à Bas Bruit de Rustrel-Pays d'Apt (Vaucluse, France). Un bon traceur hydrogéologique requiert des caractéristiques particulières (solubilité dans l'eau, stabilité, tendance faible à l'adsorption, limite de détection faible et des variations bien identifiables). Les composés organiques correspondant le mieux à ces critères sont des substances dérivées de la décomposition de la lignine. Leurs différentes caractéristiques et leurs faibles concentrations dans l'hydrosystème poussent à utiliser des modes de détection suffisamment sensibles tels que la spectrométrie de fluorescence et la Résonance Paramagnétique Électronique (RPE). L’application conjointe des analyses en RPE et en spectrofluorimétrie sur les lixiviats de sols et les eaux souterraines du LSBB permet de proposer deux protocoles de traçages hydrogéologiques. Le premier concerne la détermination des zones superficielles de sol appartenant au bassin d’alimentation des écoulements suivis. Le second, s'appuyant notamment sur l'évolution et la dynamique des MOD dans l'hydrosystème, correspond au développement de traceurs quantitatifs du temps de transit de l'eau pouvant s’appliquer de manière évènementielle par le marquage d’une période particulière de leur variation, ou en continu permettant ainsi le suivi des variations du temps de transit. Enfin, le rapprochement des résultats obtenus par ces nouveaux traceurs organiques avec ceux d'un traceur isotopique (l'oxygène 18) a permis de tester la validité des calculs du temps de transit, mais aussi de démontrer leur complémentarit

Traçage spatial et temporel des eaux souterraines dans les hydrosystèmes karstiques par les matières organiques dissoutes (expérimentation et application sur les sites du Laboratoire Souterrain à Bas Bruit (LSBB) de Rustrel Pays d'Apt et de Fontaine de Vaucluse)

Le principal objectif de ce travail est le développement, l'application et la validation de nouveaux traceurs hydrogéologiques sur la base de signatures spectrales spécifiques des matières organiques dissoutes (MOD) et du suivi de leur évolution dans les hydrosystèmes karstiques méditerranéens. Pour cela, de nombreuses analyses hydrodynamiques et hydrochimiques ont été réalisées, et plusieurs méthodes de caractérisation de la MOD ont été utilisées. Le travail s'est alors fondé sur l'étude de différents niveaux du bassin expérimental de la Fontaine de Vaucluse (sol, épikarst et zone non saturée), grâce à un accès privilégié rendu possible par le Laboratoire Souterrain à Bas Bruit de Rustrel-Pays d'Apt (Vaucluse, France). Un bon traceur hydrogéologique requiert des caractéristiques particulières (solubilité dans l'eau, stabilité, tendance faible à l'adsorption, limite de détection faible et des variations bien identifiables). Les composés organiques correspondant le mieux à ces critères sont des substances dérivées de la décomposition de la lignine. Leurs différentes caractéristiques et leurs faibles concentrations dans l'hydrosystème poussent à utiliser des modes de détection suffisamment sensibles tels que la spectrométrie de fluorescence et la Résonance Paramagnétique Électronique (RPE). L application conjointe des analyses en RPE et en spectrofluorimétrie sur les lixiviats de sols et les eaux souterraines du LSBB permet de proposer deux protocoles de traçages hydrogéologiques. Le premier concerne la détermination des zones superficielles de sol appartenant au bassin d alimentation des écoulements suivis. Le second, s'appuyant notamment sur l'évolution et la dynamique des MOD dans l'hydrosystème, correspond au développement de traceurs quantitatifs du temps de transit de l'eau pouvant s appliquer de manière évènementielle par le marquage d une période particulière de leur variation, ou en continu permettant ainsi le suivi des variations du temps de transit. Enfin, le rapprochement des résultats obtenus par ces nouveaux traceurs organiques avec ceux d'un traceur isotopique (l'oxygène 18) a permis de tester la validité des calculs du temps de transit, mais aussi de démontrer leur complémentaritéThe aim of this study is to develop, apply and validate new hydrogeological tracers, based on specific spectral fingerprints of Dissolved Organic Matter (DOM), and a monitoring of their evolution in Mediterranean karstic hydrosystems. Many hydrodynamic and hydrochemical analyses were made, and several DOM characterization methods were used. The basis of this work is therefore the study of different levels of Fontaine de Vaucluse experimental basin (soil, epikarst and unsaturated zone), thanks to a privileged access : the Low-Noise Underground Laboratory of Rustrel - Pays d Apt (Vaucluse, France). Good hydrogeological tracers require specific characteristics (water solubility, stability, a low tendency to adsorption, a low detection limit and identifiable variations). Organic compounds, corresponding to these criterions at best, are lignin-derived compounds. Their different characteristics and their low concentrations in the hydrosystem drive us to use sensitive enough detection methods, such as fluorescence spectrometry and Electronic Paramagnetic Resonance (EPR). Linked application of EPR and spectrofluorimetric analyses of leachate soil and LSBB groundwater allow to develop two hydrogeological tracing protocols. The first one concerns the determination of upper soil zone, which belongs to monitoring flow catchment area. The second one, using the evolution and the dynamics of DOM in the hydrosystem, corresponds to the development of transit time qualitative tracers, which apply either in an event-driven way by the marking of specific period of their variations, or continuously allowing the monitoring of transit time variations. Finally, the comparison between the results obtained by these new organic tracers and by an isotopic tracer (18 Oxygen) allows to validate transit time calculations and prove their complementarityAVIGNON-Bib. numérique (840079901) / SudocSudocFranceF

Organic matter as a potential complementary tool for δ 18 O data interpretation in heterogeneous aquifers†

International audienceEvaluating transit time by using δ18O seasonal variation is often difficult in a Mediterranean context due to the erratic rainfall signature added to the complexity of flow mixing. The present study aims to show that using organic matter can improve interpretations of the δ18O signal. The natural fluorescence of organic compounds and dissolved organic carbon (DOC) data were recorded in the underground low-noise laboratory, located within the catchment area of the Fontaine de Vaucluse karstic system, over a four-year period. By combining both total fluorescence and DOC, a systematic seasonal variation is observed only due to soil–water interaction. Therefore, when the recharge rate is enough at the time of the season concerned, a new specific seasonal tracer, independent of rainfall signature, is available. Besides, the DOC concentration is a tracer of rapid infiltration with short transit time associated with high DOC concentration, while long transit time waters are characterised by a low DOC concentration. Then this can also shed light on such a mixing, recent/old waters. A more sensitive interpretation of δ18O variations is then possible: if the rainfall amount and δ18O follow a seasonal trend, both tracers may be used in the same way; if the recharge is discontinuous due to discontinuous rainfall regime, δ18O tracing alone is usable; in case of erratic or smooth rainfall signature during the homogeneous rainy period, fluorescent organic matter tracing alone is then usable

Influence of Great Flood on the Functioning of Karst Aquifer: Example of the Fontaine de Vaucluse Karst System (SE France)

International audienceIn the experimental catchment area of the Fontaine de Vaucluse, a long term monitoring has been completed. It enables the study of the system functioning with variable hydrological conditions. Coupling flow rates and Mg2+ concentrations permits highlighting the particular contribution of water with great Mg2+ concentration during low water periods. It appears that these high Mg2+ concentrations are linked not only to the low flow rate itself, but also to flow rate of previous flood periods. Thus, the average residence time of discharged water during low flow period, which is usually linked to the severity of the low water level, seems to be influenced by previous flood period too. Great floods and related high pressures could lead to circulation of hardly mobilized water with very high residence time