Intrinsic vulnerability mapping for small mountainous karst aquifers, implementation of the new PaPRIKa method to Western Pyrenees (France)

International audienceThe new intrinsic vulnerability mapping method PaPRIKa is proposed as a tool to assess groundwater protection of small karst systems exploited for drinking water supply purposes in the French Pyrenees. The specific characteristics of the discontinuous carbonate aquifers of mountainous areas are here considered and taken into account into the implementation of the methodology. The Orbe site from the French Western Pyrenees area is chosen as a test site because of the relatively well known structure and behavior of the aquifer system. Steep slopes, extremely developed dissolution features, thin soils and strong dipping of geological formations are the main points to be considered. PaPRIKa method appears as a tool to assess and illustrate both the resource and source vulnerability according to the site specificities provided that appropriate field observations at a relatively high density are carried out. The vulnerability of the resource was assessed for the entire catchment area, while source-orientated mapping was attempted for the catchment area of the main capture work used for drinking water suppl

Modelling the impact of the climate change on the chalk aquifer resources (Northeastern France)

International audienc

Coupling hydrology, geochemistry and hydrodynamics towards rational management of discontinuous aquifers: application to the Ursuya massif (Basque Country, France)

The metamorphic massif of Ursuya (French Basque Country) is a strategic aquifer for the water supply of southwestern France. A multidisciplinary approach, conducted between 2009 and 2013, has led to understanding of the behaviour of this system made of discontinuous media. Isotopic and geochemical characteristics of rainwater were studied together with groundwater geochemistry, to delineate the water–rock interactions along the underground flowpaths. The chemical characteristics of groundwater, the residence times (less than 10 years to more than 50 years) and the associated mixing processes allow the achievement of a conceptual model of the groundwater flow. It highlights the role of the weathering profile from the point of view of mineralization as well as flowpaths. Finally, a quantitative approach shows highly heterogeneous hydrodynamic properties related to the weathering profile development. These results are synthesized and validated by a numerical model which forms the basis for rational management of the Ursuya aquifer in a region subject to a constant increase in water needs

Stable isotopes in precipitation of Corsica (France) and insight into insular isotopic signature of groundwater

International audienc

Groundwater flow and origin within the Biguglia lagoon watershed (Corsica, France)

International audienc

Évaluer le potentiel de contamination des eaux souterraines et de surface par les munitions nouvelles et traditionnelles

International audienceContamination of training grounds due to energetic compounds is a persistent problem both in France and in the United States. With the development of new insensitive munitions, a new set of compounds is being introduced to the environment. The new compounds are more soluble and therefore can have greater mobility in the environment and higher potential for contaminating ground and surface waters. This study is evaluating fate and transport of traditional explosive compound 1,3,5-hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) and new ones: 3-nitro-1,2,4-triazol-5-one (NTO) and 2,4-dinitroanisole (DNAN) in two environments with contrasting climatic conditions, in Camp Militaire de Bitche, in Moselle region of France, location of OHM Bitche County observatory, with wet conditions and organic soils, and in Fort Huachuca, AZ, an arid environment, in close vicinity of the Human-Environment Observatory (OHM) Pima County. Soils have been collected at both locations at or in proximity of military installations. We are conducting adsorption and transformation experiments to determine fate and transport parameters for the surface soils for both locations as well as subsoils, which are rarely examined and parameters for which are assumed. We are performing transformation experiments for both aerobic and anaerobic conditions to reflect the effect of prolonged water saturation on fate of studied compounds. Role of microorganisms in the transformation will be examined. Once parameters have been determined we will conduct modeling for both locations and several climate scenarios (current climate and projected changes in the future) to predict potential contamination.La contamination des terrains d'entraînement par des composés énergétiques est un problème persistant tant en France qu'aux États-Unis. Avec le développement de nouvelles munitions à risques atténués, un nouvel ensemble de composés est introduit dans l'environnement. Les nouveaux composés sont plus solubles et peuvent donc avoir une plus grande mobilité dans l'environnement et un potentiel plus élevé de contamination des eaux souterraines et de surface. Cette étude évalue le devenir et le transport du composé explosif traditionnel 1,3,5-hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) et des nouveaux : 3-nitro-1,2,4 -triazol-5-one (NTO) et 2,4-dinitroanisole (DNAN) dans deux environnements aux conditions climatiques contrastées, au Camp Militaire de Bitche, en Moselle (France), emplacement de l’OHM Pays de Bitche, avec des conditions humides et des sols organiques, et à Fort Huachuca, en Arizona, un environnement aride, à proximité immédiate de l’OHM Pima County. Des échantillons de sol ont été prélevés dans les deux endroits, sur ou à proximité d'installations militaires. Nous réalisons des expériences d'adsorption et de transformation afin de déterminer les paramètres de devenir et de transport des sols en surface pour les deux sites, ainsi que pour les sous-sols, qui sont rarement examinés et dont les paramètres sont supposés. Nous effectuons des expériences de transformation dans des conditions d’aérobies et anaérobies, afin de refléter l'effet d'une saturation prolongée en eau sur le devenir des composés étudiés. Le rôle des micro-organismes dans la transformation sera examiné. Une fois les paramètres déterminés, nous effectuerons une modélisation pour les deux emplacements, en tenant compte de plusieurs scénarios climatiques (climat actuel et changements prévus dans le futur) afin de prédire la contamination potentielle

Sources and behavior of perchlorate ions (ClO₄⁻) in chalk aquifer of Champagne-Ardenne, France: preliminary results

Perchlorate (ClO4−) is an environmental contaminant of growing concern due to its potential human health effects and widespread occurrence in surface water and groundwater. Analyses carried out in France have highlighted the presence of ClO4− in drinking water of Champagne-Ardenne (NW of France), with two potential sources suspected: a military source related to the First World War and an agricultural source related to the past use of Chilean nitrates. To determine the sources of ClO4− in groundwater, major and trace elements, 2H and 18O, ClO3− and ClO4− ions and a list of 39 explosives were analyzed from 35 surface water and groundwater sampling points in the east of the city of Reims. ClO4− ions were found in almost all sampling points (32 out of 35) with a max value of 33 µg L−1. ClO4− concentrations were highest in groundwater ranging from 0.7 to 33 µg L−1 (average value of about 6.2 µg L−1) against from  <  0.5 to 10.2 µg L−1 in surface water (average value of about 2.7 µg L−1). Most of the water samples showing high ClO4− levels (>  4 µg L−1) were collected near a military camp, where huge quantities of ammunitions have been used, stored and destroyed during and after the First World War

Les tourbières du camp militaire de Bitche : mémoire et rôle environnemental

International audienc

Characterization of the aquifers of the Bangui urban area, Central African Republic, as an alternative drinking water supply resource

This paper presents the results of a survey carried out in 2010 aimed at evaluating the type and quality of the groundwater resources of the Bangui region of the Central African Republic. This work is the first step towards the development of groundwater resources in the Central African Republic in order to find alternatives to direct pumping from the Ubangi River and provide the population of the suburbs with a safer drinking water supply from deep boreholes. By combining both geological and hydrogeochemical approaches, it appears that the geology of Bangui is favourable to the development of a secure and sustainable water supply from groundwater provided that the conditions of exploitation would be constrained by the local authorities. The deep Precambrian carbonate aquifers, known as the Bimbo and Fatima formations, are identified as target resources in view of the relatively good quality of their water from the chemical point of view, and the semi-confined structure of the aquifers that prevents the mixing with shallow aquifers that are already strongly affected by domestic and industrial pollution. The main difficulty in terms of exploitation is to appreciate the depth of the resource and the more or less fractured/palaeo-karstified type of the porosity