Controlled source electromagnetic measurements offshore the Maltese Islands : implications for offshore freshened groundwater in a carbonate shelf

Carbonate lithologies host considerable quantities of the Earth’s freshwater resources and partially supply a significant amount of the global population with drinkable water. Although they comprise substantial amounts of the coastlines, it is not known if these carbonate lithologies can sustain freshened groundwater offshore, and if this can help meet future water demands in coastal regions. To date, predicting volumes of freshened groundwater within marine carbonates has been challenging. Here, we integrate controlled source electromagnetic profiles with seismic reflection and core log data to derive a lithological model for the eastern carbonate margin of the Maltese Islands, one of the most water-starved countries in the world. Electrical resistivity models are used to guide lithological inference where seismic data provide limited information due to the superimposed seafloor multiple. We show that resistivity values within the Upper Coralline and Globigerina Limestone formations exceed the measured resistivity of seawater-saturated core log samples by at least a factor of four. This could be indicative of offshore freshened groundwater that occupies the pore space of the low permeability limestone along the eastern Maltese shelf. To validate this observation without further ground-truthing data, we use extensive forward modelling to show that a similar resistivity footprint can be achieved by localized interbedded low-porosity or highly cemented units. However, the spatial extent of such units across the entire eastern Maltese margin is geologically improbable. This points to the occurrence of offshore freshened groundwater that was likely emplaced during the last sea-level lowstand.peer-reviewe

Electrical resistivity anomalies offshore a carbonate coastline : evidence for freshened groundwater?

Carbonate lithologies host considerable quantities of the Earth's freshwater resources and partially supply a quarter of the global population with drinkable water. In addition, carbonates constitute substantial amounts of the global coastlines, yet it is not known if and how they can sustain freshened groundwater offshore. Here, we use controlled-source electromagnetic, seismic reflection, and core sample data to derive a lithological model for the eastern margin of the Maltese Islands and identify four distinct resistivity anomalies within the Upper Coralline and Globigerina Limestone formations. The anomalies hosted in the former are likely associated with low porosities, whereas the anomaly within the latter is indicative of pore fluid freshening. Hydrogeological modeling suggests that freshened pore fluids, emplaced during sea-level lowstands and preserved in low permeability units, are potentially still found within carbonate shelves. However, resource potential is low due to its relict nature and low permeability host environment.peer-reviewe

RESCUhE Project: Cultural Heritage vulnerability in a changing and directional climate

[EN] RESCUhE Project (Improving structural RESilience of Cultural HEritage to directional extreme hydro-meteorological events in the context of the Climate Change) is a coordinated IGME-UAM research project funded by Spanish Government (MCIN/AEI/10.13039/501100011033). The framework of this research is the predicted increase in climate change vulnerability of heritage sites and the current disconnection between both environmental research on material decay and the practical aspects of designing preventive conservation measurements.RESCUhE Project (Improving structural RESilience of Cultural HEritage to directional extreme hydro-meteorological events in the context of the Climate Change) is a coordinated IGME-UAM research project funded by Spanish Government (MCIN/AEI/10.13039/501100011033).Peer reviewe

Three-dimensional vorticity and time-constrained evolution of the Main Central Thrust zone, Garhwal Himalaya (NW India).

The use of porphyroclasts analysis for vorticity estimates is limited by the extrapolation to three dimensions of the two dimensional thin-section analysis of rigid clasts. We propose an alternative approach based on the use of X-ray micro computed tomography that offers a 3D view and thus considerably decreases the limitations of the method. Two mylonitic orthogneisses from the Munsiari Thrust, the lower boundary of the top-to-the-SW km-thick Main Central Thrust zone in the Indian Himalaya, containing K-feldspar porphyroclasts yield a kinematic vorticity ranging between 0.49 and 0.57. 40Ar/39Ar dating constrains the biotite growth on the main foliation at 4.8 ± 0.02 Ma. Adding as much information as possible to a shear zone and relating them to different pressure and temperature conditions of shear episodes recorded besides by age variations of micas is a key point to keep in mind when debating the non-cylindrical nature of Himalayan orogen

Aspect influence on the weathering micro-rates of limestones exposed under semiarid coastal Mediterranean climate

[EN] A novel methodology is presented for measuring weathering microrates after one-year of direct exposure of rocks to environment. The study focuses on building materials used in the cultural heritage exposed to semiarid coastal Mediterranean climate (SE Spain). Three different carbonate rocks, with significant differences in porosity and texture, were studied in two different exposition orientations (north and south). Results are interpreted according to local microenvironmental conditions and petrologic aspects (porosity, pore size distribution and mineralogy). South-facing rock blocks show the highest weathering microrates (9130 mm/ky and 18750 mm/ky for fine and coarse-grained porous limestones, respectively). They are 1.55 and 1.92 times higher than rates obtained in north-facing rock samples. Physical and chemical decay mechanisms overlap in the weathering process. On the one hand, physical processes are more evident in porous limestones, being predominant in south exposure samples. On the other hand, chemical corrosion is the main weathering mechanism in massive limestones as well as in porous limestones with unstable components. Dissolution prevails in northern exposure. Obtained weathering rates are two to three magnitude orders higher than the erosion rates measured in the same rocks, highlighting the conceptual differences between both parameters.This work was supported by the Spanish Ministry of Science and Innovation (MCIN) [grant numbers PID2020-116896RB-C21 and PID2020-116896RB-C22 funded by MCIN/AEI/ 10.13039/501100011033].Peer reviewe

Effect of F-Ba and Pb-Zn tailing on the mechanical and radiation shielding properties of cement mortars

[EN] The use of mine waste and tailing in concrete and mortar has widely expanded in the past years. Several studies aim to contribute to the recovery of these rejects and preserve natural raw materials, on the other hand, to improve the physio-mechanical performance of concrete. In the present investigation, the impacts of Pb-Zn and F-Ba as fine aggregate replacement in mortar were analyzed. The outcomes indicated that substitution materials affect the mechanical strength and gamma radiation shielding properties of the mortar. In this regard, the compressive strength of samples made with substitutions of 5%, 10% and 20% of F-Ba tailings were slightly decreased with those of the reference test. However, the replacements with Pb-Zn tailings cause a significant strength decrease of mortar samples (from 68% to 94%). On the contrary, the flexural strength was improved adding one of these types of tailing. Concerning the absorption properties for gamma radiation, obtained results show that incorporation of these solid residues increases the attenuation of gamma rays. The mortars made with F-Ba tailings are more effective than others. The influence of tailings is significant mainly between 0.122 and 0.622 MeV and the highest attenuation is observed for Sample 5′ and 6′. This could be explained by the relative content of heavy minerals in each waste. Furthermore, the half thickness decreases with the increase of mine tailings percentage. The difference is more marked at high energies up to 0.15 MeV. Subsequently, the obtained materials could be utilized for shielding against gamma radiation.This work was financed by the Tunisian Ministry of Higher Education and Scientific Research, “Incentive Program for Young Researchers”, Project code: 18PJEC02-04.Peer reviewe

Role of soil pore structure in water infiltration and CO2 exchange between the atmosphere and underground air in the vadose zone: A combined laboratory and field approach

The soils above caves represent a membrane that regulates the connection between the underground environment and the outside atmosphere. In this study, soils from two different field sites (Cueva de Altamira and Cueva del Rull in Spain) are investigated. Field results are analysed and linked to laboratory tests. Several laboratory experiments are performed to quantify CO diffusion coefficients and water infiltration rates in these soils under different degrees of soil water saturation and compaction. Tests confirm that the grain size distribution, organic matter content, mineral composition and water content of soils affect gas transport through the soil pore network. Both field and lab results reveal that Altamira soil has a coarser texture and therefore has higher CO diffusion coefficients, infiltration rates and hydraulic conductivity values than Rull soil. Rull soil contains a higher proportion of fine particles and organic matter, which explains the lower fluid transport coefficients. When soils are near saturation, fluid transport does not depend on the physical properties of soil but depends on the soil water content. In this state, liquid transport regulates the available space within the soil pores, which leads to a reduction in the gaseous diffusion coefficient of the soil. After rainfall episodes, the connection between the exterior atmosphere and underground cavities is hindered due to a rise in the soil water content, which is responsible for the closure of the overlying membrane. This study demonstrates that soil-produced CO reaches the underground atmosphere through diffusion processes that are controlled by the intrinsic properties of soil (porosity, grain size distribution, texture, mineralogy and organic matter content) and soil water content.This research was funded by the Spanish Ministry of Economy and Competitiveness projects CGL2011-25162 and CGL2013-43324-R and its programme Torres Quevedo (PTQ 13-06296). A pre-doctoral research fellowship (BES-2012-053468) was awarded to C. Pla for the project CGL2011-25162. Funding was also provided by the People Programme (Marie Curie Actions Intra-European Fellowships, call 2013) of the European Union's Seventh Framework Programme (FP7/2007–2013) under the REA grant agreement n° 624204.Peer Reviewe

Factors associated with COVID-19-related death in people with rheumatic diseases: results from the COVID-19 Global Rheumatology Alliance physician-reported registry

Objectives: To determine factors associated with COVID-19-related death in people with rheumatic diseases. Methods: Physician-reported registry of adults with rheumatic disease and confirmed or presumptive COVID-19 (from 24 March to 1 July 2020). The primary outcome was COVID-19-related death. Age, sex, smoking status, comorbidities, rheumatic disease diagnosis, disease activity and medications were included as covariates in multivariable logistic regression models. Analyses were further stratified according to rheumatic disease category. Results: Of 3729 patients (mean age 57 years, 68% female), 390 (10.5%) died. Independent factors associated with COVID-19-related death were age (66-75 years: OR 3.00, 95% CI 2.13 to 4.22; >75 years: 6.18, 4.47 to 8.53; both vs ≤65 years), male sex (1.46, 1.11 to 1.91), hypertension combined with cardiovascular disease (1.89, 1.31 to 2.73), chronic lung disease (1.68, 1.26 to 2.25) and prednisolone-equivalent dosage >10 mg/day (1.69, 1.18 to 2.41; vs no glucocorticoid intake). Moderate/high disease activity (vs remission/low disease activity) was associated with higher odds of death (1.87, 1.27 to 2.77). Rituximab (4.04, 2.32 to 7.03), sulfasalazine (3.60, 1.66 to 7.78), immunosuppressants (azathioprine, cyclophosphamide, ciclosporin, mycophenolate or tacrolimus: 2.22, 1.43 to 3.46) and not receiving any disease-modifying anti-rheumatic drug (DMARD) (2.11, 1.48 to 3.01) were associated with higher odds of death, compared with methotrexate monotherapy. Other synthetic/biological DMARDs were not associated with COVID-19-related death. Conclusion: Among people with rheumatic disease, COVID-19-related death was associated with known general factors (older age, male sex and specific comorbidities) and disease-specific factors (disease activity and specific medications). The association with moderate/high disease activity highlights the importance of adequate disease control with DMARDs, preferably without increasing glucocorticoid dosages. Caution may be required with rituximab, sulfasalazine and some immunosuppressants