Evolución cenozoica de la fosa de Garganta del Villar (Sistema Central español)

La fosa de Garganta del Villar (Sistema Central español) es una depresión tectónica subromboidal sobre zócalo cristalino, que localmente contiene depósitos cenozoicos (Paleógeno-Cuaternario). La interpretación geomorfológica, sedimentológica y de la mineralogía de arcillas, permite aportar nuevos datos sobre la evolución geodinámica durante el Cenozoico de este área del Macizo HercÍnico. Las etapas que configuran dicha evolución son correlacionables, en gran medida, con aquéllas establecidas por otros autores en la zona de contacto entre las grandes cuencas sedimentarias (Duero y Tajo) y el Sistema Central. Sin embargo, un buen registro de morfologías y depósitos cuaternarios de la fosa, han hecho posible matizar y complementar la sucesión de eventos pleistocenos de la misma, que evolucionó con cierta independencia respecto al resto del macizo montañoso

EDTA and hydrochloric acid effects on mercury accumulation by Lupinus albus

The efficiency of white lupine (Lupinus albus) to uptake and accumulate mercury from a soil polluted by mining activities was assessed in a pot experiment with chemically assisted phytoextraction. The mobilizing agents tested were ethylenediaminetetracetic acid (EDTA) and hydrochloric acid (HCl). Two doses of each amendment were used (0.5 and 1.0 g of amendment per kg of soil), and unamended pots were used as a control. Addition of HCl to the soil did not negatively affect plant biomass, while the use of EDTA led to a significant decrease in plant growth when compared to that found for non-treated pots, with plants visually showing symptoms of toxicity. The addition of hydrochloric acid increased root, shoot and total plant Hg uptake of white lupine by 3.7 times, 3.1 times and 3.5 times, respectively, in relation to non-amended plants. The greatest efficiency was obtained for the highest HCl dose. EDTA led to higher concentrations of total plant Hg than that found with the control, but, due to the aforementioned decrease in plant biomass, the Hg phytoextraction yield was not significantly increased. These results were attributed to the capability of both amendments to form stable Hg complexes. The concentration of Hg in the water of the soil pores after the phytoextraction experiment was very low for all treatments, showing that risks derived from metal leaching could be partially avoided by using doses and chemicals suitable to the concentration of metal in the soil and plant performance.La eficiencia del altramuz blanco ( Lupinus albus) para absorber y acumular mercurio de un suelo contaminado por actividades mineras se evaluó en un experimento en macetas con fitoextracción asistida químicamente. Los agentes movilizadores probados fueron ácido etilendiaminotetracético (EDTA) y ácido clorhídrico (HCl). Se utilizaron dos dosis de cada enmienda (0,5 y 1,0 g de enmienda por kg de suelo) y se utilizaron macetas sin enmendar como control. La adición de HCl al suelo no afectó negativamente la biomasa vegetal, mientras que el uso de EDTA condujo a una disminución significativa en el crecimiento de las plantas en comparación con el encontrado en macetas no tratadas, con plantas que mostraban visualmente síntomas de toxicidad. La adición de ácido clorhídrico aumentó la absorción de Hg de la raíz, los brotes y la planta total de altramuz blanco en 3,7, 3,1 y 3,5 veces, respectivamente, en relación con las plantas no modificadas. La mayor eficiencia se obtuvo para la dosis más alta de HCl. El EDTA dio lugar a concentraciones de Hg total de la planta más altas que las encontradas con el control, pero, debido a la disminución mencionada anteriormente en la biomasa de la planta, el rendimiento de la fitoextracción de Hg no aumentó significativamente. Estos resultados se atribuyeron a la capacidad de ambas enmiendas para formar complejos de Hg estables. La concentración de Hg en el agua de los poros del suelo después del experimento de fitoextracción fue muy baja para todos los tratamientos, lo que demuestra que los riesgos derivados de la lixiviación de metales podrían evitarse parcialmente mediante el uso de dosis y productos químicos adecuados para la concentración de metal en el suelo y el rendimiento de la planta. . el rendimiento de la fitoextracción de Hg no aumentó significativamente. Estos resultados se atribuyeron a la capacidad de ambas enmiendas para formar complejos de Hg estables. La concentración de Hg en el agua de los poros del suelo después del experimento de fitoextracción fue muy baja para todos los tratamientos, lo que demuestra que los riesgos derivados de la lixiviación de metales podrían evitarse parcialmente mediante el uso de dosis y productos químicos adecuados para la concentración de metal en el suelo y el rendimiento de la planta. . el rendimiento de la fitoextracción de Hg no aumentó significativamente. Estos resultados se atribuyeron a la capacidad de ambas enmiendas para formar complejos de Hg estables. La concentración de Hg en el agua de los poros del suelo después del experimento de fitoextracción fue muy baja para todos los tratamientos, lo que demuestra que los riesgos derivados de la lixiviación de metales podrían evitarse parcialmente mediante el uso de dosis y productos químicos adecuados para la concentración de metal en el suelo y el rendimiento de la planta.

Comparison of extractants used for the assessment of mercury availability in a soil from the Almadén mining district (Spain)

Single extraction methods have been extensively used to assess the availability of metals in polluted soils. This work focused on checking the feasibility of several chemicals, i.e. CaCl2, EDTA, diethylenetriaminepentaacetic acid (DTPA) and a low-molecular-weight organic acid mixture (rhizosphere-based method), to be used as extractants for mercury (Hg) in a soil from the Almadén mining district (Spain). Moreover, the effect of several experimental parameters, i.e. extraction time (0.5, 1, 2, 5, 16 and 24 h), concentration of extractant (0.01, 0.05, 0.1 and 1 M) and soil/extractant ratio (1:2, 1:5 and 1:10), on the amount of Hg extracted was investigated. The Hg extraction ability followed the descending order EDTA > rhizosphere-based method > DTPA ≈ CaCl2. This ranking was attributed to the higher complexation power of EDTA and organic acids. It was also found that extraction times between 2 and 5 h are required to avoid underestimation of mobile Hg and re-adsorption of the Hg previously extracted. Although some exceptions were found, Hg extraction efficiency was generally enhanced with higher extractant concentrations. Finally, the amount of Hg extracted by the four extractants increased with decreasing soil/extractant ratios

Performance of waste-based amendments to reduce metal release from mine tailings: One-year leaching behaviour

A one-year leaching experiment has been conducted in order to assess the effectiveness of several amendments on metal immobilization in mine tailings from an old Pb/Zn mining area of Central Spain (San Quintín mine). Demineralized water was used as leaching solution, selecting doses equivalent to the annual rainfall conditions of the studied area. Columns with mine tailings without any amendment and others treated with 10% of sugar foam (SF), 15% of drinking water treatment sludge (DWS), 30% of paper mill sludge (PMS) and 15% of olive mill waste (OMW) were used. SF, DWS and PMS amendments increased the pH of leachates from values of approximately 4 to around neutrality. Additionally, the release of sulfate ions from the oxidation of pyritic residues was decreased in some extent by SF and DWS amendments. Metal leaching was effectively reduced by the amendments reaching overall decreases with respect to the unamended columns of 79–96% for Pb, 36–100% for Zn, 50–99% for Cu and 44–100% for Cd. The effect of the amendments in leachate pH, sulfate concentration and metal release from mine tailings was kept throughout the whole experimental period. Our results showed that the application of different organic and inorganic amendments based on by-products and waste materials may be a feasible alternative for the restoration of soils around abandoned metal mines.Se ha realizado un experimento de lixiviación de un año para evaluar la efectividad de varias enmiendas sobre la inmovilización de metales en relaves mineros de una antigua zona minera de Pb / Zn en el centro de España (mina San Quintín). Se utilizó agua desmineralizada como solución de lixiviación , seleccionando dosis equivalentes a las condiciones de precipitación anual del área de estudio. Columnas con relaves mineros sin enmienda y otras tratadas con 10% de espuma de azúcar (SF), 15% de lodos de potabilización (DWS), 30% de lodos de papelera (PMS) y 15% de residuos de almazara (OMW) fueron usados. Las enmiendas SF, DWS y PMS aumentaron el pH de los lixiviados de valores de aproximadamente 4 a aproximadamente neutralidad. Además, el lanzamiento deLos iones sulfato de la oxidación de residuos piríticos disminuyeron en cierta medida por las enmiendas SF y DWS. La lixiviación de metales se redujo efectivamente con las enmiendas que alcanzaron disminuciones generales con respecto a las columnas sin enmendar de 79–96% para Pb, 36–100% para Zn, 50–99% para Cu y 44–100% para Cd. El efecto de las enmiendas en el pH del lixiviado, la concentración de sulfato y la liberación de metales de los relaves de la mina se mantuvo durante todo el período experimental. Nuestros resultados mostraron que la aplicación de diferentes enmiendas orgánicas e inorgánicas basadas en subproductos y materiales de desecho puede ser una alternativa viable para la restauración de suelos alrededor de minas de metales abandonadas

Palaeogeographical significance of clay mineral assemblages in the Permian and Triassic sediments of the SE Iberian Ranges, eastern Spain

The evolution of the palaeogeography of the SE Iberian Basin during the Permian and Triassic represents a general evolution from continental to marine environments. It has been recently studied from the sedimentological, stratigraphical, tectonic and palaeontological points of view. In spite of these results, many aspects of this palaeogeography are still a matter of discussion. In this study, clay mineralogy analysis complements previous studies representing a new aspect for understanding the evolution of the sedimentary environment and the palaeogeography of the Iberian Basin during the periods in question and thus of the palaeogeography and the location of the major high areas in the westernmost border of the Tethys sea. In spite of late diagenetic transformations the original clay mineral associations of the Permian-Triassic sediments of the SE Iberian Ranges can be reconstructed. Seventy-seven samples of siliciclastic and carbonate sediments of these ages have been studied (SEM and XRD), revealing six new aspects that help to precise the palaeogeographical interpretation of the area: (1) Two major mineral assemblages have been found: illite+ kaolinite +pyrophyllite in the continental facies and illite + chlorite + vermiculite + mixed-layer clays in the marine facies. (2) The Mg-rich clay minerals are here considered to be of marine origin. (3) Active phases of basin boundary faults are marked in the sediments by the presence of pyrophyllite, derived directly from the Palaeozoic metamorphic basement. (4) Unconformities separating major depositional sequences also separate formations with different clay mineralogy. (5) Different groups of clay minerals can be separated clearly coinciding with the different palaeogeographical stages also distinguished in the westernmost border of the Tethys sea. (6) The clay mineral associations back up the data of a previous hypothesis of a humid climate for the end of the Permian in the study area just prior to the first incursion of the Tethys sea

Studying the feasibility of a selection of Southern European ceramic clays for the production of lightweight aggregates

Nine clays traditionally used in the ceramic brick and tile sector in Southern Europe were evaluated for the production of lightweight aggregates: four from Spain, three from Portugal and two from Italy. The clays’ suitability was thoroughly examined according to their capacity for pelletizing, their tendency to burst during heating, the firing temperature and their technological properties. A greater proportion of phyllosilicates over nonplastic components is directly related to the bursting of the pellets during preheating. Increased sand contents and SiO2/(∑Flux = K2O + Na2O + CaO + MgO + FeO + Fe2O3) ratios are connected to higher firing temperatures, the opposite occurring with the MgO percentage. Those clays with a higher iron content (highlighting in this study the two Italian clays and the Spanish red one) would be more optimal for the development of an expanded structure. The findings of this work show that Southern Europe holds clay deposits with enormous potential in the production of lightweight aggregates. In particular, the red clay from the Zocca deposit (Italy) is remarkable for its excellent characteristics for the production of expanded lightweight aggregates (bloating index of 24.4% and loose bulk density of 0.47 g/cm3). These raw materials could have a new market line due to the multiple applications of lightweight aggregate in construction (lightweight concrete), horticulture as well as in civil and environmental engineering.This research was conducted as a part of the SmartMats Project (MAT2015-70034-R), “Smart materials for sustainable construction”, funded by the Spanish Ministry of Economy and Competitiveness and FEDER (MINECO-FEDER). The authors gratefully acknowledge this support. The authors also gratefully acknowledge the technical and human support provided by CICT of the University of Jaén and the University of Málaga (UJA, MINECO, Junta de Andalucía, FEDER)

Unraveling the expansion mechanism in lightweight aggregates: Demonstrating that bloating barely requires gas

Lightweight aggregate bloating process has been studied by a simple experiment using an archetypal clay to know the actual amount of gas involved in expansion. Considering the relationship between gas loss (LOI) and volumetric changes over time, three main stages are identified: 1) a preheating stage of massive gas loss (close to 80% of the total) with hardly any volumetric change; 2) a very brief transition stage, in which sintering (shrinkage) and closed (micro)porosity formation begin, accompanied by a sudden gas loss (close to 100% of the total); 3) the bloating stage itself, in which an appropriate viscosity is reached, allowing the available residual gas (<0.1 wt%) to increase the aggregate volume due to the growth in size of the micropores formed in the transition phase and probably also to the development of new porosity. Therefore, the proportion of gas-generating components estimated to obtain a highly expanded lightweight aggregate would be much lower than previously thought: e.g., only 0.06 to 0.2% of carbonates (calcite or dolomite) or 0.2 to 1% of Fe2O3 would actually be involved in bloating. These results suggest that obtaining an adequate viscosity appears to be much more decisive for bloating than gas release capacity.This research was conducted as a part of the SmartMats Project (MAT2015-70034-R), “Smart materials for sustainable construction”, funded by the Spanish Ministry of Economy and Competitiveness and FEDER (MINECO-FEDER). The authors gratefully acknowledge this support. The authors also gratefully acknowledge the technical and human support provided by CICT of the University of Jaén and the University of Málaga (UJA, MINECO, Junta de Andalucía, FEDER)

Comprehensive study of electrokinetic-assisted phytoextraction of metals from mine tailings by applying direct and alternate current

Electrokinetic-assisted phytoextraction (EKPH) involves the use of electric current to improve the mobilization of metals in soils and, therefore, their removal efficiency. It emerges as an interesting sustainable technology for the rehabilitation of abandoned mining areas. The goal of this research was to conduct a comprehensive study of this technique applied to real mine tailings from an abandoned Pb/Zn mine by using ryegrass as plant species and two types of electric current: direct with polarity reversal (DC-PR) and alternate (AC). The EKPH tests were conducted in specially designed plastic containers that allowed recording the main parameters of the electrokinetic process and sampling the different matrices studied, i.e. water, soil and plants. This intensive sampling program allowed detailed monitoring of the metal mobilization processes for the different treatments applied. The changes caused in metal mobility and physicochemical parameters of the tailings due to the application of electric current were reflected to a greater extent in the water samples than in solid ones. Accumulation of Pb, Zn, Cd and Cu in ryegrass tissues increased significantly by 41%, 17%, 34% and 32% when applying 1 V cm−1 of AC current, with respect to the results of phytoextraction without electric current. The application of DC-PR current did not lead, in general, to statistically significant increases in the plant metal uptake. These findings were adequately correlated with the changes found in the metal concentrations of soil pore water and, to a lesser extent, with those observed from the BCR sequential extraction applied to tailings samples.La fitoextracción electrocinética asistida (EKPH) implica el uso de corriente eléctrica para mejorar la movilización de metales en suelos y, por tanto, su eficiencia de eliminación. Surge como una interesante tecnología sostenible para la rehabilitación de zonas mineras abandonadas. El objetivo de esta investigación fue realizar un estudio exhaustivo de esta técnica aplicada a estériles mineros reales procedentes de una mina abandonada de Pb/Zn utilizando ryegrass como especie vegetal y dos tipos de corriente eléctrica: continua con inversión de polaridad (DC-PR) y alterna (AC). Los ensayos EKPH se realizaron en recipientes de plástico especialmente diseñados que permitieron registrar los principales parámetros del proceso electrocinético y muestrear las distintas matrices estudiadas, es decir, el agua, el suelo y las plantas. Este programa intensivo de muestreo permitió un seguimiento detallado de los procesos de movilización de metales para los diferentes tratamientos aplicados. Los cambios provocados en la movilidad de los metales y en los parámetros fisicoquímicos de los estériles debido a la aplicación de corriente eléctrica se reflejaron en mayor medida en las muestras de agua que en las sólidas. La acumulación de Pb, Zn, Cd y Cu en los tejidos de ryegrass aumentó significativamente en un 41%, 17%, 34% y 32% al aplicar 1 V cm-1 de corriente AC, respecto a los resultados de la fitoextracción sin corriente eléctrica. La aplicación de corriente DC-PR no condujo, en general, a incrementos estadísticamente significativos en la captación de metales por la planta. Estos resultados se correlacionaron adecuadamente con los cambios encontrados en las concentraciones metálicas del agua de poro del suelo y, en menor medida, con los observados a partir de la extracción secuencial BCR aplicada a muestras de estériles

Does environmental risk really change in abandoned mining areas in the medium term when no control measures are taken?

Studies regarding how environmental risk evolves in abandoned mining areas in the medium term have been seldom carried out. The answer to this question is not obvious despite it is essential in order to evaluate the need to take urgent control measures in these areas. Fifty-two samples corresponding to soils (from natural pasture and arable lands) and mine tailings were collected in the surroundings of an old Spanish Pb/Zn mine (San Quintín, Central Spain). Current concentrations of pseudo-total and available metal (loid)s (Pb, Zn, Cd, Cu, As and Ag) were determined and the environmental risk assessment (ERA) was conducted with these data and those corresponding to a sampling previously carried out in 2006. ERA was carried out by calculating the geoaccumulation index (Igeo), the pollution load index (PLI) and the potential ecological risk index (PER). Results demonstrated that Pb and Zn concentrations have increased in the soils of the plots surrounding the mining areas causing a moderate rise in most of the determined pollution indices between 2006 and 2020. It was especially significant in the pastureland areas, with increases up to 17% in the number of soil samples that reached the highest risk classification in 2020 as compared to those taken in 2006. The results obtained here demonstrate that the environmental risk can actually increase in a continuous way in abandoned mining areas despite the closure of the mining operation and the effect of the possible natural attenuation.Pocas veces se han realizado estudios sobre cómo evoluciona el riesgo ambiental en áreas mineras abandonadas a mediano plazo. La respuesta a esta pregunta no es obvia, aunque es fundamental para evaluar la necesidad de tomar medidas urgentes de control en estas áreas. Se recogieron 52 muestras correspondientes a suelos (de pastos naturales y tierras de cultivo) y relaves de mina en el entorno de una antigua mina española de Pb/Zn (San Quintín, Centro de España). Se determinaron las concentraciones actuales de metales (loid)s pseudototales y disponibles (Pb, Zn, Cd, Cu, As y Ag) y con estos datos y los correspondientes a un muestreo realizado previamente se realizó la evaluación de riesgo ambiental (ERA). en 2006. ERA se realizó calculando el índice de geoacumulación(Igeo), el índice de carga contaminante (PLI) y el índice de riesgo ecológico potencial (PER). Los resultados demostraron que las concentraciones de Pb y Zn han aumentado en los suelos de las parcelas aledañas a las zonas mineras provocando un aumento moderado en la mayoría de los índices de contaminación determinados entre 2006 y 2020. Fue especialmente significativo en las zonas de pastoreo, con incrementos de hasta el 17%. en el número de muestras de suelo que alcanzaron la clasificación de mayor riesgo en 2020 en comparación con las tomadas en 2006. Los resultados aquí obtenidos demuestran que el riesgo ambiental puede aumentar de manera continua en áreas mineras abandonadas a pesar del cierre de la operación minera y el efecto de la posible atenuación natural

Petrographic and geochemical evidence for multiphase formation of carbonates in the Martian orthopyroxenite Allan Hills 84001

This research has been funded by the Spanish Ministry of Science and Innovation (projects: AYA2011‐26,522, AYA 2015‐67175‐P, CTQ2015‐62,635‐ERC, and CTQ2014‐60,119‐P to which J.M. Trigo‐Rodríguez and C.E. Moyano‐Cambero acknowledge financial support). The UK Science and Technology Facilities Council is also thanked for funding through grants ST/H002960/1, ST/K000942/1, and ST/L002167/1. ICN2 and ICMAB acknowledge support of the Spanish MINECO through the Severo Ochoa Centers of Excellence Program under Grants SEV‐2013‐0295 and SEV‐2015‐0496, respectively. We acknowledge B. Ballesteros and M. Rosado from the ICN2 Electron Microscopy Division, and A. Fernández from the ICTS (National Center of Electronic Microscopy) for the SEM, EDS, and microprobe measurements. We also thank the NASA Meteorite Working Group, and the Johnson Space Center for providing the ALH 84001,82 section. This study was done in the frame of a PhD on Physics at the Autonomous University of Barcelona (UAB) under the direction of J. M. Trigo‐Rodríguez.Peer reviewedPublisher PD