F-bearing sediments and rocks in the East African Rift: characterization and evaluation of F release capacity

Fluoride represents one of the most severe natural contaminant that affects groundwater as well as rivers and soils. More than 200 million people worldwide consume water with fluoride concentration exceeding the WHO guideline of 1.5 mg L-1 (WHO, 2008)

Three-dimensional hydrostratigraphical modelling supporting the evaluation of fluoride enrichment in groundwater: Lakes basin (Central Ethiopia)

Study region: The Lakes Basin is located in the Main Ethiopian Rift. It covers the northern part of the rift valley basin, the Upper Awash River basin, and some sub-basins from the Omo River basin. Due to the presence of high fluoride (F−) content, natural contamination of groundwater has long been recognized as a water-related health issue in the area. Study focus: A multidisciplinary research effort, including geological, hydrogeological, hydro-chemical, and geophysical investigations, was adopted to understand the 3D hydrogeological conceptual model and to evaluate F− enrichment in groundwater. New hydrological insights for the region: The 3D hydrogeological conceptual model shows a complex hydrogeological environment and a clear hydraulic interconnection between different aquifers. The geological setting has deeply influenced the geometry of the aquifers, recharge and discharge areas, and F− enrichment in groundwater. Two hydrogeological units, namely sedimentary and volcanic multi-aquifers, were identified. The analyses of groundwater circulation, flow paths, and distribution of F- concentrations in each aquifer were conducted. In groundwater, the concentration of fluoride varies from 0.1 to 68.9 mg L−1; in surface water, it ranges from 0.6 to 244.2 mg L−1. Fluoride concentration of 62 % of the water samples analyzed exceeded the 1.5 mg L−1 WHO threshold for fluoride concentration in drinking water. The proposed methodological approach has been demonstrated to be a powerful tool that could be applied in other similar areas

Geologic evolution of the Cerro Quema Au-Cu deposit, Azuero Peninsula (Panama)

Central America hosts a variety of metallic mineral resources including Au, Cu, Ag, Pb, Zn, Ni, Co, Sb, W, and Al, spanning a broad range of deposit types. In Panama, Au and Cu are the most economically important metals, and they are mainly related to epithermal and porphyry copper systems.\ud \ud Cerro Quema is a high sulfidation epithermal deposit located in the Azuero Peninsula (SW Panama), it is constituted by serveral mineralized bodies named from W to E: La Pava, Cerro Quemita and Cerro Quema. Estimated Au resources are 7.23 Mt with an average gold grade of 1.10 g/T. Cerro Quema is located in the fore-arc basin of the Panamanian Cretaceous volcanic arc. It is related to an E-W trending regional fault system, and is hosted by the dacite dome complex of the Río Quema Formation (Campanian to Maaastrichtian in age).\ud \ud Hydrothermal alteration consits of an inner zone of nearly pure quartz (vuggy silica alteration), with local quartz-alunite and pyrophyllite alteration (advanced argillic alteration), enclosed by a kaolinite, illite and illite/smectite-bearing zone (argillic alteration), grading to an external halo of propylithic alteration. \ud \ud Gold occurs as disseminated submicroscopic grains and "invisible gold" within the pyrite lattice. Copper is associated to Cu-bearing phases such as chalcopyrite, enargite, tennantite, covellite and chalcocite. \ud \ud Cerro Quema was formed by fluids derived from the emplacement of an underlying porphyry copper intrusion emplaced along E-W trending regional faults located in the Cretaceous fore-arc basin, during Paleogene times. The proposed geologic model suggests that high sulfidation epithermal deposits are not exclusive of volcanic edifices or volcanic domes related to subduciton zones. This deposits can also occur in fore-arc basins, associated with acidic intrusions located between the volcanic arc front and the subduction trench. This should be taken into account for exploration in geologically similar terranes

REE and Sm-Nd clues of high-temperature fluid-rock interaction in the Riópar dolomitization (SE Spain)

Trabajo presentado en el 15th Water-rock Interaction International Symposium, celebrado en Evora (Portugal), del 16 al 21 de octubre de 2016REE geochemistry and Sm-Nd isotope data of Mesozoic stratabound and patchy dolostones of the Riópar area (Prebetic Zone, SE Spain) are presented. The results, combined with previously published data, suggest the dolomitizing fluid was a warm brine that interacted with siliciclastic rocks of Triassic age and with the host carbonates at low fluid-rock ratios. The positive Eu anomaly, negative ɛNd values and MREE patterns confirm that the dolostones were formed by interaction with warm acidic crustal fluids. C-O isotopic interaction models indicate that these fluids were characterized by δ18O-enriched and δ13C-depleted compositions, pointing to low ratios of fluid to rock volumes. The studied dolostones show two Sr sources: one Sr signature is close to the host carbonate values and the other one is more radiogenic, indicating that fluids became enriched in 87Sr after interacting with siliciclastic rocks. Furthermore, the Sr-Nd isotope data systematic depicts a positive correlation, thus probably the same rock sources are shared for both elements. Moreover, the warm fluids interacted with regional limestones achieving a negative Ce and positive La anomalies, low δ18O compositions and similar δ13C values than the host carbonates.Peer reviewe

Assessment of two complementary influenza surveillance systems : Sentinel primary care influenza-like illness versus severe hospitalized laboratory-confirmed influenza using the moving epidemic method

Monitoring seasonal influenza epidemics is the corner stone to epidemiological surveillance of acute respiratory virus infections worldwide. This work aims to compare two sentinel surveillance systems within the Daily Acute Respiratory Infection Information System of Catalonia (PIDIRAC), the primary care ILI and Influenza confirmed samples from primary care (PIDIRAC-ILI and PIDIRAC-FLU) and the severe hospitalized laboratory confirmed influenza system (SHLCI), in regard to how they behave in the forecasting of epidemic onset and severity allowing for healthcare preparedness. Epidemiological study carried out during seven influenza seasons (2010-2017) in Catalonia, with data from influenza sentinel surveillance of primary care physicians reporting ILI along with laboratory confirmation of influenza from systematic sampling of ILI cases and 12 hospitals that provided data on severe hospitalized cases with laboratory-confirmed influenza (SHLCI-FLU). Epidemic thresholds for ILI and SHLCI-FLU (overall) as well as influenza A (SHLCI-FLUA) and influenza B (SHLCI-FLUB) incidence rates were assessed by the Moving Epidemics Method. Epidemic thresholds for primary care sentinel surveillance influenza-like illness (PIDIRAC-ILI) incidence rates ranged from 83.65 to 503.92 per 100.000 h. Paired incidence rate curves for SHLCI-FLU/PIDIRAC-ILI and SHLCI-FLUA/PIDIRAC-FLUA showed best correlation index' (0.805 and 0.724 respectively). Assessing delay in reaching epidemic level, PIDIRAC-ILI source forecasts an average of 1.6 weeks before the rest of sources paired. Differences are higher when SHLCI cases are paired to PIDIRAC-ILI and PIDIRAC-FLUB although statistical significance was observed only for SHLCI-FLU/PIDIRAC-ILI (p-value Wilcoxon test = 0.039). The combined ILI and confirmed influenza from primary care along with the severe hospitalized laboratory confirmed influenza data from PIDIRAC sentinel surveillance system provides timely and accurate syndromic and virological surveillance of influenza from the community level to hospitalization of severe cases