Characterizing groundwater flow and heat transport in fractured rock using Fiber-Optic Distributed Temperature Sensing

International audienceWe show how fully distributed space-time measurements with Fiber-Optic Distributed Temperature Sensing (FO-DTS) can be used to investigate groundwater flow and heat transport in fractured media. Heat injection experiments are combined with temperature measurements along fiber-optic cables installed in boreholes. Thermal dilution tests are shown to enable detection of cross-flowing fractures and quantification of the cross flow rate. A cross borehole thermal tracer test is then analyzed to identify fracture zones that are in hydraulic connection between boreholes and to estimate spatially distributed temperature breakthrough in each fracture zone. This provides a significant improvement compared to classical tracer tests, for which concentration data are usually integrated over the whole abstraction borehole. However, despite providing some complementary results, we find that the main contributive fracture for heat transport is different to that for a solute tracer

XAFS evidence for amorphous zinc sulfide as a major zinc species in suspended matter from the Seine River downstream of Paris, Ile-de-France, France

International audienceZinc is one of the most widespread Trace Metals (TMs) in Earth surface environments and is the most concentrated TM in the downstream section of the Seine River (France) due to significant anthropogenic input from the Paris conurbation. In order to better identify the sources and cycling processes of Zn in this River basin, we investigated seasonal and spatial variations of Zn speciation in suspended particulate matter (SPM) in the oxic water column of the Seine River from upstream to downstream of Paris using synchrotron-based Extend X-ray Absorption Fine Structure (EXAFS) spectroscopy at the Zn K-edge. First-neighbor contributions to the EXAFS were analyzed in SPM samples dried and stored under a dry nitrogen atmosphere or under an ambient oxygenated atmosphere. We found a sulfur first coordination environment around Zn (in the form of amorphous zinc sulfide) in the raw SPM samples stored under dry nitrogen vs. an oxygen first coordination environment around Zn in the samples stored in an oxygenated atmosphere. These findings are supported by scanning electron microscopic and energy dispersive X-ray spectrometry observations. Linear combination fitting of the EXAFS data for SPM samples, using a large set of EXAFS spectra of Zn model compounds, indicate dramatic changes in the Zn speciation from upstream to downstream of Paris, with amorphous ZnS particles becoming dominant dowstream. In contrast, Zn species associated with calcite (either adsorbed or incorporated in the structure) are dominant upstream. Other Zn species representing about half of the Zn pool in the SPM consist of Zn-sorbed on iron oxyhydroxides (ferrihydrite and goethite) and, to a lesser extent, Zn-Al layered double hydroxides and Zn incorporated in dioctahedral layers of clay minerals. Our results highlight the importance of preserving the oxidation state in TM speciation studies when sampling suspended matter, even in an oxic water column. They also demonstrate that systematic use of such careful sampling procedures may reveal the presence of reduced solid phases that might have been overlooked in previous studies of type B metal-bearing samples in oxic surface water columns

Multi-disciplinary characterizations of the BedrettoLab – a new underground geoscience research facility

The increased interest in subsurface development (e.g., unconventional hydrocarbon, engineered geothermal systems (EGSs), waste disposal) and the associated (triggered or induced) seismicity calls for a better understanding of the hydro-seismo-mechanical coupling in fractured rock masses. Being able to bridge the knowledge gap between laboratory and reservoir scales, controllable mesoscale in situ experiments are deemed indispensable. In an effort to access and instrument rock masses of hectometer size, the Bedretto Underground Laboratory for Geosciences and Geoenergies ("BedrettoLab") was established in 2018 in the existing Bedretto Tunnel (Ticino, Switzerland), with an average overburden of 1000 m. In this paper, we introduce the BedrettoLab, its general setting and current status. Combined geological, geomechanical and geophysical methods were employed in a hectometer-scale rock mass explored by several boreholes to characterize the in situ conditions and internal structures of the rock volume. The rock volume features three distinct units, with the middle fault zone sandwiched by two relatively intact units. The middle fault zone unit appears to be a representative feature of the site, as similar structures repeat every several hundreds of meters along the tunnel. The lithological variations across the characterization boreholes manifest the complexity and heterogeneity of the rock volume and are accompanied by compartmentalized hydrostructures and significant stress rotations. With this complexity, the characterized rock volume is considered characteristic of the heterogeneity that is typically encountered in subsurface exploration and development. The BedrettoLab can adequately serve as a test-bed that allows for in-depth study of the hydro-seismo-mechanical response of fractured crystalline rock masses.ISSN:1869-9510ISSN:1869-952

Atopic dermatitis phenotypes in childhood.

none6noBackground Atopic dermatitis (AD) is a chronic inflammatory skin disease and can be the first step of the atopic march. Objective In this retrospective study, we analysed the immunological and clinical patterns of AD in a group of children affected by the disease since their first years of life, in order to evaluate if and how these patterns can change over time, and to identify biomarkers that can possibly correlate with the clinical phenotype. Methods We enrolled Caucasian children with diagnosis of AD performed by a specialist on the basis of Hanifin and Rajka?s criteria and with a first clinical and laboratory evaluation before 5?years of age. Patients were divided in 2 groups: IgE-associated AD (with or without allergic respiratory diseases) and non-IgE-associated AD. Results Among 184 patients enrolled in this study, at the beginning 30/184 were classified as having non-IgE-associated AD, but during follow-up, at the median age of 36?months, 15 patients became allergic. All 15 patients who switched from the non-IgE to the IgE-associated form had a significantly earlier onset of AD than those who did not switch. Dust mite sensitization seem to be the best biomarker (OR 2.86) to predict the appearance of allergic respiratory diseases. Conclusion IgE-associated AD is more frequent in childhood than non-IgE-associated AD. These two phenotypes are different in the age of onset and in the remission patterns. In the first years of life, it is important to distinguish the different phenotypes in order to evaluate possible allergic related conditions.noneRicci G; Dondi A; Neri I; Ricci L; Patrizi A; Pession A.Ricci G; Dondi A; Neri I; Ricci L; Patrizi A; Pession A