Hydrochemical characterization of a mine water geothermal energy resource in NW Spain

Abandoned and flooded mine networks provide underground reservoirs of mine water that can be used as a renewable geothermal energy source. A complete hydrochemical characterization of mine water is required to optimally design the geothermal installation, understand the hydraulic behavior of the water in the reservoir and prevent undesired effects such as pipe clogging via mineral precipitation. Water pumped from the Barredo-Figaredo mining reservoir (Asturias, NW Spain), which is currently exploited for geothermal use, has been studied and compared to water from a separate, nearby mountain mine and a river that receives mine water discharge and partially infiltrates into the mine workings. Although the hydrochemistry was altered during the flooding process, the deep mine waters are currently near neutral, net alkaline, high metal waters of Na-HCO3 type. Isotopic values suggest that mine waters are closely related to modern meteoric water, and likely correspond to rapid infiltration. Suspended and dissolved solids, and particularly iron content, of mine water results in some scaling and partial clogging of heat exchangers, but water temperature is stable (22 °C) and increases with depth, so, considering the available flow (> 100 L s− 1), the Barredo-Figaredo mining reservoir represents a sustainable, long-term resource for geothermal use

MERCURY PARTITIONING IN THE WATER COLUMN OF EL ENTREDICHO OPEN-PIT (ALMAD\uc9N, SPAIN)

The Almad\ue9n mercury (Hg) mining district (Ciudad Real, central Spain) is located within the largest geochemical anomaly of this element in the world. The district includes a series of deposits that comprise a variety of structural and textural styles sharing a simple paragenesis, where a dominant cinnabar mineralization is associated with other accessory minerals but in very low proportions to be considered the deposits as monomineral. An intensive mining activity has been developed during more than 2000 years, leaving an important number of decommissioned mines and liabilities scattered in the area. Among the several sites of exploitation, El Entredicho (Fig. 1) is the most peculiar since it is an unusual open-pit mine which was in operation only for Hg extraction. It is the second mine in importance within the district which produced 290,000 flask of Hg in nineteen years of exploitation. As a consequence of the mine operations, a big hole was created (87,500 m2 of surface and 72 m of depth) which was restored by flooding with waters from the near Valdeazogues River in 1998. Today, this open-pit only receives waters from runoff without other inputs from ground or surface waters. Due to this unusual environmental setting, water column has evolved in isolation during the last seventeen years making this artificial lake a unique laboratory for investigating mercury biogeochemical processes in an isolated freshwater environment. This research focuses on a preliminary characterization of Hg abundance and fractionation in the water column of El Entredicho open-pit to understand the effects of physical and biogeochemical factors on the distribution of Hg specie

Heavy metals and metalloids in sediments of the Nalon River estuary saltmarsh (Northern Spain)

El estuario del r\uedo Nal\uf3n ha venido recibiendo durante los \ufaltimos 200 a\uf1os un aporte continuo de materiales procedentes de actividades minero-industrial es localizadas en su cuenca hidrogr\ue1fica.Como consecuencia de los aportes de metales y metaloides en diferentes fases, los sedimentos del estuario han visto incrementadas significativamente sus concentraciones en algunos elementos con respecto al fondo geoqu\uedmico natural de la zona. La aplicaci\uf3n al estudio de \uedndices normalizados de referencia como el \ucdndice de Geoacumulaci\uf3n o el Factor de Enriquecimiento han mostrado que a determinadas profundidades los sedimentos de las marismas presentan concentraciones especialmente elevadas en As, Pb y Zn, y estas anomal\uedas geoqu\uedmicas se consideran atribuibles a la actividad antropog\ue9nica como fuente principal de aporte

TRACE METALS ENRICHMENT IN THE SEDIMENTS OF A MINING IMPACTED ESTUARY (NORTH OF SPAIN)

Trace elements are important components of natural water systems. Their behaviour is carefully investigated in environmental studies due to their key role in biogeochemical processes involving water, sediments and biota. Natural concentrations of trace elements in these matrices primarily depend on the local lithological and mineralogical characteristics. Unfortunately, as a result of human activities, the contemporary environment has been affected by several additional sources of trace elements, such as potentially toxic metals and metalloids. If the anthropogenic inputs of these elements in the natural systems exceed the local background values, we can expect to observe some effects on their biogeochemical cycles. These may also result in their anomalous accumulation in biota and, possibly, in human beings through fish and mussel consumption. Estuaries represent unique water systems, a vital link between the land and the sea. Due to mixing of fresh and seawater, estuaries are characterized by pronounced gradient of many parameters such as salinity, temperature, pH, redox potential as well as suspended particle matter composition. Besides, they often act as a trap for material brought by rivers, which may also include various contaminants, included potentially toxic elements, associated with anthropogenic activities. The primary aim of this work was to investigate the geochemical characteristics of the present sediments of the Nal\uf3n River estuary compared to the local geochemical background in order to assess possible anomalies due anthropogenic contributions which can have altered their lithogenic properties. For this purpose, spatial and temporal distributions of major and trace elements in the sediments were deeply investigated

Determinaci\uf3n de valores geoqu\uedmicos de fondo para la evaluaci\uf3n del enriquecimiento por metales y metaloides en los sedimentos estuarinos del R\uedo Nal\uf3n (Norte de Espa\uf1a)

This study aims at establishing the regional background levels and upper thresholds (geochemical baseline) for some potentially toxic elements (As, Cr, Hg, Pb, Sb and Zn) in coastal sediments from two boreholes of the Nal\uf3n estuary, N-Spain. By applying a statistical approach, the outliers were identified and removed from the original dataset along with elemental concentration values not representative of the natural sedimentary environment. Results showed significant enrichments in element concentrations at the most recent sedimentary layers. This enrichment has been attributed to historical anthropogenic activities developed within the drainage the basin, and, for Hg, As and Sb, it is mainly due to mining contribution

Predictive factors of six-week mortality in critically ill patients with SARS-CoV-2: A multicenter prospective study.

The objective of the study is to identify the risk factors associated with mortality at six weeks, especially by analyzing the role of antivirals and munomodulators. Prospective descriptive multicenter cohort study. 26 Intensive care units (ICU) from Andalusian region in Spain. Consecutive critically ill patients with confirmed SARS-CoV-2 infection were included from March 8 to May 30. None. Variables analyzed were demographic, severity scores and clinical condition. Support therapy, drug and mortality were analyzed. An univariate followed by multivariate Cox regression with propensity score analysis was applied. 495 patients were enrolled, but 73 of them were excluded for incomplete data. Thus, 422 patients were included in the final analysis. Median age was 63 years and 305 (72.3%) were men. ICU mortality: 144/422 34%; 14 days mortality: 81/422 (19.2%); 28 days mortality: 121/422 (28.7%); 6-week mortality 152/422 36.5%. By multivariable Cox proportional analysis, factors independently associated with 42-day mortality were age, APACHE II score, SOFA score at ICU admission >6, Lactate dehydrogenase at ICU admission >470U/L, Use of vasopressors, extrarenal depuration, %lymphocytes 72h post-ICU admission 6, Lactate dehydrogenase at ICU admission >470U/L, Use of vasopressors, extrarenal depuration, %lymphocytes 72h post-ICU admission 470U/L, Use of vasopressors, extrarenal depuration, %lymphocytes 72h post-ICU admission Age, APACHE II, SOFA>value of 6 points, along with vasopressor requirements or renal replacement therapy have been identified as predictor factors of mortality at six weeks. Administration of corticosteroids showed no benefits in mortality, as did treatment with tocilizumab. Lopinavir/ritonavir administration is identified as a protective factor