Monitoring geomagnetic signals of groundwater movement using multiple underground SQUID magnetometers

International audienceGroundwater can influence the geomagnetic field measured underground in at least two key ways. The water levels in rock will determine its electrical conductivity, and thus change the magnitude of the telluric currents induced in the rock by changing magnetic fields generated in the ionosphere. This can be studied by using multiple magnetometers at different underground locations. Secondly the flow of water through rock will generate a small magnetic signal, of unknown magnitude, through the electrokinetic effect. SQUID magnetometry has the potential to allow passive studies of groundwater changes in complex systems such as karst. We have monitored geomagnetic signals using two SQUID magnetometers at the LSBB underground laboratory, and set an initial limit on the magnitude of the electrokinetic signal. We now plan to carry out a longer term measurement using three SQUID systems as well as fluxgate sensors to track changes in the gradient of the magnetic field across the underground complex

Hydrodynamic organisation of the flows in the unsaturated zone of the Fontaine de Vaucluse karst system. First results

International audienceKarst systems contain important groundwater resources. Due to their complexity, they are generally under exploited. Particularly, the hydrodynamic functioning of the unsaturated zone is badly understood even if its important role is admitted Today, the hydrogeologists are agreeing with the important function(s) of the unsaturated zone in karst systems, but today this role(s) is badly characterized. As they are very complex systems, karst aquifers are generally under exploited. It is necessary to progress in the understanding of the functioning of the karst systems and particulary in the functioning of the unsaturated zone in order to develop the corresponding management tools. The study of the unsaturated zone of a karst system needs some access to this part of the aquifer. Speleological access is not sufficient because the major part of the water flows in not humanly enterable drains. The Low-Noise Underground Laboratory of Rustrel-Pays d'Apt (LSBB) is an artificial gallery digged in the unsaturated zone of the Fontaine de Vaucluse karst aquifer catchment area. It intersects arbitrarily the fault networks in depth and then the potential areas of flows through the unsaturated zone. From 2002 to 2009, 61 points where water regularly flows have been identified. For each, flow rate has been periodically monitored. This first global study of the acquired data shows a good relation between flows and geological structures. An organization of flows with depth and geology is also underlined. With increasing depth, flows seem to concentrate from numerous faults networks to a little number of high discontinuities

Search for a geomagnetic signal produced by the movement of groundwater in fractured carbonate rock.

International audienc

An overview of recent [SQUID]² activities.

session III: Couplings: solid Earth, atmosphere and near UniverseInternational audienc

Monitoring magnetotelluric signals with multiple underground SQUID magnetometers.

session posterInternational audienc

Exploration of the earth magnetic field transmission through the karstic mountain of Rustrel

session G (P20)International audienc

The Calm Mouse: An Animal Model of Stress Reduction

Chronic stress is associated with negative health outcomes and is linked with neuroendocrine changes, deleterious effects on innate and adaptive immunity, and central nervous system neuropathology. Although stress management is commonly advocated clinically, there is insufficient mechanistic understanding of how decreasing stress affects disease pathogenesis. Therefore, we have developed a “calm mouse model” with caging enhancements designed to reduce murine stress. Male BALB/c mice were divided into four groups: control (Cntl), standard caging; calm (Calm), large caging to reduce animal density, a cardboard nest box for shelter, paper nesting material to promote innate nesting behavior, and a polycarbonate tube to mimic tunneling; control exercise (Cntl Ex), standard caging with a running wheel, known to reduce stress; and calm exercise (Calm Ex), calm caging with a running wheel. Calm, Cntl Ex and Calm Ex animals exhibited significantly less corticosterone production than Cntl animals. We also observed changes in spleen mass, and in vitro splenocyte studies demonstrated that Calm Ex animals had innate and adaptive immune responses that were more sensitive to acute handling stress than those in Cntl. Calm animals gained greater body mass than Cntl, although they had similar food intake, and we also observed changes in body composition, using magnetic resonance imaging. Together, our results suggest that the Calm mouse model represents a promising approach to studying the biological effects of stress reduction in the context of health and in conjunction with existing disease models