Application des techniques physiques, géochimiques et isotopiques pour l'évaluation de l'infiltration sous climat tempéré

Depuis plusieurs années, la Zone Non Saturée d'une parcelle expérimentale au nord de l'Italie (plaine du Pô) a fait l'objet de nombreuses études sur les caractéristiques physiques et géologiques du milieu, ainsi que sur les modalités du mouvement des eaux d'infiltration. Le site a été équipé de 6 tensiomètres à mercure, 6 bougies poreuses pour l'échantillonnage de l'eau et d'un tube d'accès pour la sonde à neutrons.L'application des différentes méthodes d'évaluation a fourni, pour la période d'étude (Septembre 1994-Août 1995), des valeurs de l'infiltration sensiblement différentes. La méthode physique, basée sur le calcul du bilan hydrique annuel, et considérant le sol comme un unique réservoir monocouche, a indiqué que 19% du total des précipitations arrive à s'infiltrer. D'autre part, un modèle de simulation intégrant les caractéristiques hydrodynamiques du sol a permis d'évaluer la recharge à 29% des précipitations annuelles. Le calcul de la répartition de la teneur en eau sur le profil porte sur la description des fluctuations temporelles du plan de flux nul, en relation avec les épisodes pluvieux et l'intensité de l'évaporation.La méthode géochimique du "profil en ions conservés" entre l'eau de pluie et du sol a permis, quant à elle, d'évaluer la lame d'eau infiltrée à environ 12% des précipitations annuelles. La composition isotopique des eaux extraites du sol manifeste un enrichissement global en isotopes lourds (2H et 18O) par rapport aux eaux météoriques, conséquence d'une évaporation intense. L'infiltration semble être de type "piston flow" dispersif. Elle suit, seulement pendant l'hiver, un flux où la composante convective dans la microporosité est prédominante sur la composante diffusive qui a lieu, de préférence, dans la macroporosité.In groundwater management, it is necessary to define water movement, evaluate infiltration and evapotranspiration rates, and quantify the physico-chemical evolution of transported solutes throughout the unsaturated zone (UZ). Traditionally, in temperate regions, recharge rate is evaluated by the comparison between physical methods (based on direct measurements of hydrological parameters with lysimeters, tensiometers and neutron gauges) and geochemical approaches (conservative ions, stable isotope profiles and artificial tracers).In the Po Plain (Northern Italy) intensive agricultural irrigation and overexploitation of groundwater profoundly affect the quality and availability of shallow groundwater resources. The region has been intensively cultivated with corn and rice during the last 5 centuries. Irrigation canals have been constructed in order to distribute water from alpine rivers to areas more favourable to agriculture. In the past, only the water balance method has been applied to obtain recharge rates in these situations.An experimental field site has been operational since 1987 in the ENEA-EUREX Nuclear Centre of Saluggia. The experimental plot represents an unsaturated zone in fluvio-glacial deposits (Holocene) of the Dora Baltea River, formed by gravel and sand, interlayered with silt levels. The water table is usually at a depth of 200 cm but it varies as a function of the river level. The objectives of the present study were to describe water movement throughout the UZ and to evaluate infiltration and evapotranspiration rates using different physico-chemical methodologies. The Saluggia plot was equipped with six tensiometers, a neutron gauge hole and 6 porous cups, up to a depth of 160 cm.During 10 years of monitoring, the most favourable period for understanding infiltration processes and water movement through the UZ is September 1994 - August 1995. This period is characterised by an exceptional rain event (300 mm in 48 hours), followed by a river flood. Water samples collected with porous cups at various depths have been analysed for chemistry and stable isotope composition, together with rainfall and Dora Baltea River water.In October 1994 (beginning of the rainy period) and May 1995 (beginning of the dry period) soil samples were collected at different depths and water was extracted under vacuum conditions. Stable isotope analyses were performed on extracted waters. Soil samples were also analysed for granulometry, chemical and mineralogical composition.Reducing soil to an unique monolayer aquifer, the water balance method suggests that only 19% of the total precipitation infiltrates, whereas a simulation model taking into account soil hydrodynamic characteristics estimates an infiltration rate of 29% of the rainfall. The position of the Zero Flux Plane (ZFP) fluctuates seasonally between the surface and the maximum studied depth, as a consequence of precipitation events and evaporation fluxes. In some periods, the ZFP is level with the water table and direct discharge may occur.Measurements of the stable isotopic composition (δ2H and δ18O) of soil water allows a quantitative estimate of direct groundwater discharge. On a δ2H versusδ18O plot, pore waters from the UZ have an isotopic composition that differs from that of the majority of groundwater samples, plotting below the local rain water line and indicating some degree of evaporation during the recharge process. The isotopic enrichment is particularly significant at the evaporation front, suggesting that pore water in soil reflects a different recharge regime from those of the regional ground waters. Water isotope and solute composition were substantially modified from their original composition during the infiltration process within the soil, via mechanisms such as anion exchange with soil particles, salt precipitation/dissolution or isotopic fractionation.Arial recharge was also evaluated using the depth distribution of a conservative solute. Assuming that chloride is derived from precipitation alone, Cl- content in soil and in rain water suggests that 12% of total rainfall infiltrates. Therefore, the recharge rate is estimated to be less than 100 mm/a. These data are in agreement with other results obtained by the chloride concentration profile method, in areas of the Po Valley, but are considerably different from those evaluated by the traditional physical methods

Homogénéisation des signaux isotopiques, 18O et 3H, dans un système hydrologique de haute montagne : la Vallée d'Aoste (Italie)

L'analyse de l'origine et de la dynamique des écoulements souterrains dans l'aquifère du milieu alluvial de la plaine d'Aoste (Italie) a été menée en étudiant les teneurs isotopiques (18O et 3H) des eaux sur l'ensemble du système hydrologique. La démarche a consisté en un suivi isotopique des précipitations pluvio-neigeuses, des sources de versants, du réseau de surface et de l'aquifère alluvial, complété par des analyses ponctuelles concernant l'horizon superficiel des glaciers et les sous-écoulements glaciaires. Le signal d'entrée en 18O porté par les précipitations présente une grande variabilité liée au contexte orographique (effet d'écran) et climatique (pluie ou neige). Celle-ci est mise en évidence par les changements saisonniers du gradient 18O/altitude. En moyenne annuelle (1994), ce gradient établi en Vallée d'Aoste à partir de mesures sur les précipitations récoltées entre 300 et 3500 m d'altitude (sur huit stations) est de - 0.18 ± 0.02 ‰ pour 100 m, avec un écart-type (s) des valeurs de ± 4,8 ‰. L'ensemble des résultats en 18O montre au cours du cycle hydrologique, un amortissement à la fois important et progressif du signal d'entrée fourni par les précipitations. Cet amortissement, de l'ordre de 30 fois dans l'aquifère alluvial (sigma=± 0.15 ‰), est particulièrement sensible au niveau de la glace et des sous-écoulements glaciaires. En ce qui concerne les résultats en 3H, les teneurs mesurées dans les précipitations se révèlent être étroitement liées avec l'origine et la trajectoire des masses d'air humide. Par ailleurs, on note une bonne concordance entre les temps de séjour des eaux dans l'aquifère alluvial calculés à partir des valeurs en 18O et ceux fournis par le 3H.The hydrogeological study of the alluvial aquifer of the Aosta plain (Italy) is chosen as one of the most appropriate examples representative of the Italian-French-Swiss Alps. This study has been carried out using two environmental isotopes (18O and 3H) for groundwater samples taken from this aquifer in order to shed light on the origin of water and the hydrodynamic characteristics of the aquifer.The surface area of this aquifer is 70 km_ and mean elevation ranges between 400 and 700 m (asl). This surface area constitutes a part of the watershed area that amounts 2400 km_ with a mean elevation of 2200 m (asl). The watershed possesses several mountain peaks, Mt. Blanc, Mt. Cervin, Mt. Grand Paradis, the elevation of which rise to over 4000 m.The input signal, quantitative and qualitative as well, provided by the precipitation shows a wide variability linked to both orographic (screen effect) and climatic (rain or snow) influences. This variability is marked by differences in the 18O/altitude gradient, which is seasonally dependent. A unique and linear relation is observed during spring and summer ; in autumn and winter results show an important gradient up to 2000 m but a less important one for higher altitudes.The mean annual (1994) gradient of - 0.18 ± 0.02 ‰ for 100 m is determined in Aosta valley for altitudes between 300 and 3500 m, and the standard deviation (sigma) of the mean volume-weighted value for precipitation is ± 4.8 ‰. Furthermore, the 18O values measured in the alluvial aquifer have shown a very low dispersion (sigma=± 0.15 ‰), which corresponds to a buffering effect of a factor 30. These results evidenced, thus, an homogenization process within the different water bodies.To analyze this homogenization process, the different components of the hydrologic system have been studied, i.e. the monitoring of the springs and runoff waters, with complementary local measurements of the upper part of ice cores and the glacier underflows. Using standard deviations (sigma) as criteria for the homogenization process, one can see a large and progressive decrease along the hydrological cycle, with a special amplitude in ice cores and glacier underflows : precipitation (± 4.8 ‰), ice core (± 0.8 ‰), glacier underflow (± 0.10 ‰), spring (± 0.15 ‰), surface runoff network (± 0.3 ‰), alluvial aquifer (± 0.15 ‰).In ice cores, the different process : freezing and thawing, compression, and vapor / liquid / solid exchanges have caused the 18O homogenization. Dealing with the springs on the slopes of the valley, the preferential flow paths linked to the fracturation lead to a mixing of waters and hence to a very buffered outflow signal. The combined effect of all these explains the stability and the uniformity of the data found in the alluvial water body.As far as the 3H concentrations are concerned, the values measured are tightly linked with the origin and the transport of humid air masses. For closely spaced stations, a significant difference in the input signal has been correlated to various climatic influences. Using 3H data from the Thonon-les-Bains station (included in the WMO-IAEA observation network) as input, the calculated transit times of 2.5 to 7.5 years are very close to those calculated with 18O, i.e. 4 to 7 years

c myc deregulation is involved in melphalan resistance of multiple myeloma role of pdgf bb

Oncogenes are important regulators of cancer growth and progression and their action may be modulated by proteins of the growth factor family, such as angiogenic cytokines, known to be strongly involved in neoplastic evolution. Reciprocal interactions between oncogenes and angiogenic modulators may represent, in haematological neoplasms, including multiple myeloma (MM), a possible mechanism of drug resistance. The aim of this work is to investigate in vitro and in vivo whether or not c-myc deregulation is involved in the melphalan resistance elicited by myeloma patients and consequently to clarify the role of the angiogenic factor PDGF-BB in modulating c-myc protein expression. Fifty-one MM patients on chemotherapy with melphalan were analyzed for structural alterations of the c-myc gene, c-Myc protein expression, as well as for serum PDGF-BB release. For the in vitro study, two M14-derived established cell clones, differing for the c-Myc protein expression (c-Myc low -expressing or constitutively express..

Quantitative Metabolomics by 1H-NMR and LC-MS/MS Confirms Altered Metabolic Pathways in Diabetes

Insulin is as a major postprandial hormone with profound effects on carbohydrate, fat, and protein metabolism. In the absence of exogenous insulin, patients with type 1 diabetes exhibit a variety of metabolic abnormalities including hyperglycemia, glycosurea, accelerated ketogenesis, and muscle wasting due to increased proteolysis. We analyzed plasma from type 1 diabetic (T1D) humans during insulin treatment (I+) and acute insulin deprivation (I-) and non-diabetic participants (ND) by 1H nuclear magnetic resonance spectroscopy and liquid chromatography-tandem mass spectrometry. The aim was to determine if this combination of analytical methods could provide information on metabolic pathways known to be altered by insulin deficiency. Multivariate statistics differentiated proton spectra from I- and I+ based on several derived plasma metabolites that were elevated during insulin deprivation (lactate, acetate, allantoin, ketones). Mass spectrometry revealed significant perturbations in levels of plasma amino acids and amino acid metabolites during insulin deprivation. Further analysis of metabolite levels measured by the two analytical techniques indicates several known metabolic pathways that are perturbed in T1D (I-) (protein synthesis and breakdown, gluconeogenesis, ketogenesis, amino acid oxidation, mitochondrial bioenergetics, and oxidative stress). This work demonstrates the promise of combining multiple analytical methods with advanced statistical methods in quantitative metabolomics research, which we have applied to the clinical situation of acute insulin deprivation in T1D to reflect the numerous metabolic pathways known to be affected by insulin deficiency

Incorporating the social dimension into hydrogeochemical investigations for rural development: the Bir Al-Nas approach for socio-hydrogeology

A replicable multidisciplinary approach is presented for science-based groundwater management practices: Bir Al-Nas (Bottom-up IntegRated Approach for sustainabLe grouNdwater mAnagement in rural areaS). This approach provides a practical example of the concept of “socio-hydrogeology”, a way of incorporating the social dimension into hydrogeological investigations, as reinforced by the translation of the Arabic bir al-nas: “the people’s well”. To achieve this, hydrogeologists act as “social hydrologists” during their monitoring activities, which often bring them into contact with local communities and end users (and polluters) of water. Not only can they retrieve reliable information about traditional know-how and local issues, but they can also change the public perception of science/scientists to create the basis for mutual collaboration and understanding in view of implementing improved integrated groundwater management. The final outcomes are expected to be an increased awareness of communities at the local level and a clear understanding of their water issues and needs from the very early stages of the investigation. Although the importance of using such methods in groundwater analysis and management is widely recognized, hydrogeological investigations are currently dominated by sectorial approaches that are easier to implement but less sustainable. The pressure of population growth, the shift towards more water-dependent economies, climate change and its impact on water availability will require scientists to use a more integrated approach, such as Bir Al-Nas, when dealing with increasing water pollution and water-scarcity issues.A replicable multidisciplinary approach is presented for science-based groundwater management practices: Bir Al-Nas (Bottom-up IntegRated Approach for sustainabLe grouNdwater mAnagement in rural areaS). This approach provides a practical example of the concept of "socio-hydrogeology", a way of incorporating the social dimension into hydrogeological investigations, as reinforced by the translation of the Arabic bir al-nas: "the people's well". To achieve this, hydrogeologists act as "social hydrologists" during their monitoring activities, which often bring them into contact with local communities and end users (and polluters) of water. Not only can they retrieve reliable information about traditional know-how and local issues, but they can also change the public perception of science/scientists to create the basis for mutual collaboration and understanding in view of implementing improved integrated groundwater management. The final outcomes are expected to be an increased awareness of communities at the local level and a clear understanding of their water issues and needs from the very early stages of the investigation. Although the importance of using such methods in groundwater analysis and management is widely recognized, hydrogeological investigations are currently dominated by sectorial approaches that are easier to implement but less sustainable. The pressure of population growth, the shift towards more water-dependent economies, climate change and its impact on water availability will require scientists to use a more integrated approach, such as Bir Al-Nas, when dealing with increasing water pollution and water-scarcity issues

A model for water sharing in the Ganges River Basin

This study investigates water resources sharing and in particular the impact of the Farakka Barrage in the Ganges River Basin management which has led to conflict between the Ganges states since 1951. A deadlock prevailed between Bangladesh and India during the dry seasons. The 1996 water sharing treaty adopted and the results suggest that availability of flows is crucial during the period 1 March to 31 May. Moreover, the average flow availability at Farakka dam has been gradually declining during the period 1997 to 2007. For 2005 and 2006, it was found that the average flow availability declined by 12 and 25%, respectively. A Stackelberg leader–follower model is described for optimal water allocation in the Ganges River Basin between Bangladesh and India both with and without additional water transfers from Nepal. It is recommended that a market-based water transfer arrangement from Nepal is implemented for both Bangladesh and India.

New geophysical knowledge of groundwater systems in Venice estuarine environment

Unconfined aquifers beneath the south sector of the Venice Lagoon are characterized by the presence of saline water. The results of this study allow the determination of the superficial extension of the salt water contamination in the direction of the mainland and the relationship between chemical analysis and conductivity, which reveals a complex lateral and vertical variability in both the permeability and textural pattern. Moreover, geophysical data validated by log data together with other physical and chemical results show a dislocation of the aquifer basement. This fact allows for the presumption that the salt groundwater distribution is affected by a regional tectonic lineament which extends towards the SE. Therefore salt contamination may be due to saline intrusion from the sea and the lagoon, and also from fossil brines mobilised by the combined action of tectonics and infiltration of fresh groundwater