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The use of aluminum-rich clays and bauxites as refractory materials is common. Upon firing, these materials form mullite crystals in the shape of needles embedded in a siliceous and vitreous matrix, with mullite being responsible for the refractory properties. In this study, bauxite samples for use in refractory applications have been characterized. Chemical analysis revealed that the alumina content varied between 34 and 40%, with silica values generally being high (around 40%), except for one sample (26%). Two samples were found to be the most suitable for use as “refractory clay” refractories. However, high silica or Fe oxide contents can affect mineralogical transformations at high temperatures. Mineralogical analysis confirmed the presence of several minerals in the bauxite materials, including kaolinite, halloysite, anatase, rutile, gibbsite and boehmite. Differential thermal analysis (DTA) showed the decomposition of gibbsite and its partial transformation to boehmite and alumina, and the dehydroxylation of kaolinite, with primary mullite crystallization observed at a high temperature. These findings provide valuable information for the selection and optimization of bauxite materials for refractory applications, considering their chemical composition and mineralogical characteristics.

Este estudio investiga los efectos de implementar un proyecto de catalogación de minerales en una escuela de primaria, con el objetivo de promover la participación activa de los estudiantes, fomentar su colaboración y trabajo en equipo, así como mejorar su interés y comprensión en el campo de las Ciencias de la Tierra. Además, se proporciona una guía detallada para los docentes que deseen realizar una clase sobre identificación de minerales con sus estudiantes, centrándose principalmente en el aprendizaje de las propiedades de los minerales. La intervención se llevó a cabo en una clase de cuarto grado de Educación Primaria en el colegio C.E.I.P. Las Razas, ubicado en Sevilla, This study investigates the effects of implementing a mineral cataloging project in an elementary school, aiming to promote active student participation, foster collaboration and teamwork, and enhance their interest and understanding of Earth Sciences. Additionally, a detailed guide is provided for teachers who wish to conduct a lesson on mineral identification with their students, focusing primarily on learning about mineral properties. The intervention took place in a fourth-grade class at C.E.I.P. Las Razas School, located in Sevilla

Sulfidic mine wastes have the potential to generate acid mine drainage (AMD) and release acid leachates containing high levels of iron, sulfate and potentially toxic elements (PTEs). Soils receiving AMD discharges are generally devoid of vegetation. Only a few metal-tolerant plant species can survive under such adverse soil conditions. This work investigates two plant species, Nicotiana glauca and Euphorbia segetalis, that have successfully colonized an AMD-impacted wetland area in south-western Spain. The uptake of PTEs from the soil by roots and their transfer and accumulation in the above-ground biomass were quantified. Results showed that these pioneer plants grew in patches of neutral soil within the wasteland despite the high concentrations of PTEs in the rhizosphere soil (up to: 613 mg kg−1 As, 18.7 mg kg−1 Cd, 6370 mg kg−1 Cu, 2210 mg kg−1 Pb and 5250 mg kg−1 Zn). The target organs of As, Cu and Pb accumulation were: root > leaf > stem in N. glauca, and root > stem > leaf in E. segetalis. Zinc and Cd showed a significant decrease in roots relative to aerial parts of N. glauca, and Co was preferentially partitioned in stems of N. glauca and leaves of E. segetalis. The soil–plant transfer coefficient values of PTEs in all parts of both plants were well below unity with the only exception of Cd in leaves of N. glauca (1.254), suggesting that roots acted as a barrier limiting the uptake of PTEs by plants. Interestingly, under the same soil conditions, N. glauca absorbed Cd in considerable proportions from soil and accumulated it in its leaves, while E. segetalis was not effective in transferring PTEs from roots shoots except for Co. In conclusion, soil pH and plant-related factors greatly influence the stabilization of PTE in the rhizospheric soil and produce inconsistencies in PTE phytoavailability. The findings of this study provide criteria to assist in natural remediation in other legacy contaminated sites worldwide.

Mineralogical analysis and laboratory-based leaching tests coupled with speciation modeling were undertaken to quantify the potential for short-term acid generation and the release of trace elements from soils heavily contaminated with mine waste at Rio Tinto. Three different waste materials were considered as case studies: roasted pyrite, copper slags, and leached sulfide ores. The results showed elevated values of net acid generation (up to 663 mmol H+/kg), the major pools being potential sulfidic acidity and acidity retained in jarosite. Remarkable contents of As and toxic heavy metals were found especially in the slag-contaminated soil. Copper, Zn, and Pb were the most abundant metals in the acid leach solutions resulting from mine soil-water interaction, with peak values of 55.6 mg L−1 , 2.77 mg L−1 , and 2.62 mg L−1 , respectively. Despite the high total contents of trace elements occurring in soil, the mobile fraction was limited to maximum release values of 12.60% for Cd and 10.27% for Cu, according to the test leaching. Speciation calculations indicated that free metal ions (M2+) and sulfate species (MSO4 0 ) accounted for most of the dissolved load. Acid soil drainage is a secondary source of acid and heavy metals in the mine site and, therefore, an effective land reclamation program should ensure that acidity and metal mobility are reduced to environmentally sustainable levels.

Currently, only 50% of concrete produced from construction and demolition waste is being recycled in Europe. This falls short of the European Union’s target of 70% by 2020. Moreover, this figure only considers coarse fractions (>4 mm), as technical issues arise when using fine fractions. In pursuit of a complete circular life for recycled concrete, this investigation explores the potential use of fine fractions to enhance the physicochemical conditions and reduce the element concentration of acid mine drainage. Two trickling sets were prepared using a filter holder, with acidic waters passing through a layer of recycled concrete aggregates. Results revealed an immediate increase in water pH to neutral levels, a reduction in solution oxidation, and the complete, or near-complete retention, of potentially toxic elements by the substrate (with retention percentages of over 99.9% for Al and Fe, between 43.1% and 61.1% for S, over 91.1% for Zn, and over 99.1% for Cu). The experiment also showed a significant increase in Ca levels (tripling the initial value) and some Mg in the water, which could promote the subsequent precipitation of carbonates and the retention of trace metals. In summary, this study demonstrates the effectiveness of using recycled concrete aggregates in a laboratory setting. Further investigation is necessary to evaluate the feasibility of implementing this technique at the pilot scale

El estuario del río Guadiana se encuadra en el Sur de la Península Ibérica, concretamente en la frontera entre España y Portugal; el río atraviesa en su último tramo la Faja Pirítica Ibérica, donde se localizan importantes yacimientos mineros que han sido explotados en los últimos 5000 años. Ante el peligro que los drenajes ácidos, producidos por este tipo de actividades, suponen para el medio ambiente, se ha realizado un estudio mediante la extracción de testigos, a los que se les han aplicado diferentes métodos (estudio de su química, datación por C14, y estudio mineralógico) que han permitido obtener resultados que dejan al descubierto un sistema capaz de amortiguar de una forma natural muy eficiente los aportes que han llegado de la parte alta de la cuenca durante los últimos 13000 años, protegiendo así un ecosistema con un alto valor ecológico., The estuary of the Guadiana River is located in the South of the Iberian Peninsula, specifically on the border between Spain and Portugal. The river crosses in its last section the Iberian Pyrite Belt, where there are important mining deposits that have been exploited during the last 5000 years. Given the danger that Acid Drainage, produced by this type of activity, pose to the environment, a study has been carried out through the extraction of cores, to which different methods have been applied (study of their chemistry, dating by C14, and mineralogical study) through which results have been obtained that reveal a system capable of dampening in a quite forceful way the contributions that have come from the upper part of the basin during the last 13000 years, thus protecting an ecosystem with a high ecological value.

A field-based experiment was set up to evaluate the effectiveness of a single application of marble waste sludge (MWS) on chemical immobilization of potentially hazardous trace elements (PHE) within the soil profile of a mine Technosol under natural assisted remediation for 12 years. Results showed that MWS amendment significantly reduced soil acidity and PHE mobility compared to unamended soil, thus improving soil health and plant growth. The amendment application had a sustained acid-neutralizing action, as soil pH remains relatively constant at between 5.8 and 6.4 throughout the entire profile (70 cm depth). In addition to diluting pollutants, the treatment triggered a redistribution of trace elements among the various operationally defined geochemical pools, shifting the PHE speciation from water-soluble forms to fractions associated with carbonates (29% Cd), metal oxides (40–48% Zn, Cd, Cu, and Ni), organic matter (22% Cu and Ni), and insoluble secondary oxidation minerals and residual phases (80–99% As, Cr, Sb, Tl, and Pb), thereby effectively limiting its potential environmental significance. MWS treatment to immobilize PHE in the contaminated mine Technosol was effective and persistent while in the untreated soil metal release is continuing over time.

En este trabajo se ofrece una idea para la de creación de un recurso educativo que une la enseñanza de una materia, como las Ciencias de la Tierra, concretamente la Geología, con el uso de las nuevas tecnologías TIC, en concreto, la Realidad Aumentada o RA a partir de ahora. El objetivo del trabajo es obtener un recurso que permita a los docentes ampliar la enseñanza tradicional de estos contenidos mediante esta tecnología y no solo dentro del aula, sino también de forma online, permitiendo a los alumnos acceder fácilmente a ellos mediante dispositivos electrónicos accesibles. Para ello, a lo largo de este trabajo se reflexiona sobre la necesidad de adecuar la educación a los tiempos modernos y a la enseñanza online de calidad. El trabajo de revisión ofrece una idea de la situación de las Ciencias de la Tierra y las TICs en el modelo educativo actual. Se detalla el recurso educativo propuesto, así como una valoración de sus puntos fuertes y débiles, para acabar el presente trabajo con un análisis profundo y con las conclusiones finales., This work offers an idea for the creation of an educational resource that unites the teaching of a subject, such as Earth Sciences, specifically Geology, with the use of new ICT technologies, specifically, Augmented Reality or AR from now on. The aim of this work is to obtain a resource that allows teachers to expand the traditional teaching of these contents through this technology and not only in the classroom, but also online, allowing students to easily access them through accessible electronic devices. To this end, throughout this work it reflects on the need to adapt education to modern times and to a quality online teaching. The review work offers an idea of the situation of Earth Sciences and ICTs in the current educational model. The proposed educational resource is detailed, as well as an assessment of its strengths and weaknesses, to end this work with an in-depth analysis and final conclusions

En este trabajo se describe el taller de geología inclusiva «Ahora toca… la roca», realizado en el marco colaborativo entre la Universidad de Sevilla (US), la Universidad de Barcelona (UB) y la Organización Nacional de Ciegos Españoles (ONCE). La actividad se realizó en el Centro de Recursos Educativos de la ONCE de Sevilla (CRE) para estudiantes con discapacidad visual (DV) de secundaria y bachillerato pertenecientes a las comunidades autónomas de Andalucía y Extremadura. La experiencia se desarrolló dentro del Servicio de Educación Combinada Grupal (SECG) «¡Ponte a punto!» que ofrece la ONCE. El taller trató sobre el ciclo de las rocas; en particular, los procesos geológicos por los que atraviesan las rocas para transformarse en alguno de los tres tipos básicos: ígneas, sedimentarias o metamórficas. El alumnado participante en el taller, a través de la manipulación sistemática y dirigida pudo comprobar y así afianzar mejor los conocimientos acerca de la transformación que sufren las rocas. El alto grado de participación y la positiva valoración por parte del alumnado estuvieron motivados por el detallado diseño, la adaptación de los contenidos desde la perspectiva de la percepción háptica o tacto activo, la motivación del equipo educativo y su carácter multidisciplinar., This paper describes the inclusive geology workshop «Ahora toca... la roca», carried out in a collaborative framework among the University of Seville (US), the University of Barcelona (UB) and the Spanish National Organisation for the Blind (ONCE). The activity was carried out at the ONCE Educational Resources Centre in Seville (CRE) for visually impaired high school pupils from the Autonomous Regions of Andalusia and Extremadura. The experience was implemented within the Combined Group Education Service (SECG) «¡Ponte a punto!» offered by the ONCE. The workshop dealt with the rock cycle; in particular, the geological processes that rocks go through to become one of the three basic types: igneous, sedimentary or metamorphic. Through systematic and guided handling, the pupils participating in the workshop were able to verify and thus consolidate their knowledge of the transformation undergone by rocks. The high level of participation and the positive assessment by the pupils were the result of the detailed design, the adaptation of the contents from the perspective of haptic perception or active touch, the motivation of the educational team and its multidisciplinary character.

Acid mine drainage is one of the main environmental hazards to ecosystems worldwide and it is directly related to mining activities. In Ecuador, such acidic-metallic waters are drained to rivers without treatment. In this research, we tested a laboratory combined (Ca-Mg) Dispersed Alkaline Substrate (DAS) system as an alternative to remediate acid drainage from the Zaruma-Portovelo gold mining site, at El Oro, Ecuador. The system worked at low and high flow hydraulic rates during a period of 8 months, without signs of saturation.. Analysis of physico-chemical parameters and water composition (ICP-OES, ICP-MS) demonstrated that treatment effectively increased water pH and promoted the retention of about 80% of Fe, Al, Mn and Cu. Under acid conditions As, Cr and Pb concentrations decreased with Fe and possible precipitation of jarosite and schwertmannite. However, the homogeneous depletion of Cr at pH above 6 could be related to ferrihydrite or directly with Cr (OH)3 precipitation. After DAS-Ca, sulphate, phosphate and rare earth elements (REE) concentrations decreased to 1912, 0.85 and 0.07 mg/L respectively, while DAS-Mg contributed to form a complex model of minor carbonate and phosphate phases as main sink of REE. DAS-Mg also promoted the retention of most divalent metals at pH values over seven. Thus, this low cost treatment could avoid environmental pollution and international conflicts. Anyway, further investigations are needed to obtain higher Zn retention values.

En esta ponencia se presenta un mapa conceptual sobre las condiciones geoambientales del río Tinto (Huelva), uno de los ecosistemas más singulares de nuestro planeta debido a la extrema acidez y a las elevadas concentraciones de sulfatos y metales pesados que transportan sus aguas. El mapa conceptual se ha elaborado con la herramienta FreeMind (software libre basado en Java) y aborda conceptos troncales, como el origen y las fuentes de contaminación hídrica, que derivan de forma progresiva y jerárquica hacia aspectos más específicos y complejos, como el proceso de generación de aguas ácidas, el impacto ambiental sobre el medio físico, biológico y socioeconómico, y la composición química y mineralógica de los sedimentos y suelos afectados., In this paper, we present a concept map for organizing and representing knowledge about geo-environmental conditions of the Tinto River (Huelva), a unique ecosystem on Earth due to the extreme acidity and high concentrations of sulphates and heavy metals dissolved in the water. The concept map was drawn with the software FreeMind (a mind-mapping tool based on Java) showing how that specific topics, such as processes of acid mine drainage formation, environmental impacts, and chemical and mineralogical composition of sediments and soils affected, stemming from the main concepts (origin, sources and effects of water pollution).

Recent studies have demonstrated that the Guadiana Estuary contains metal concentrations in excess of background values. Therefore, this work aims to document the potential environmental hazards associated with the availability of these metals in this environment of high ecological value. Mineralogical analysis shows that the sediments are composed mainly of quartz, albite, and clay minerals (illite, smectite, kaolinite, and vermiculite) along with several small, reactive compounds (including soluble sulphated salts, Fe–Mn oxyhydroxides, organic matter, and pyrite) capable of retaining metals, which can be subsequently released, causing environmental degradation. BCR sequential extraction shows that As, Cd, Cu, Mn, Pb, and Zn present mobile fractions with respect to the total metal content (41, 100, 57, 53, 70, and 69%, respectively) in any of the described reactive phases (F1 + F2 + F3).Calculated environmental risk indices demonstrate moderate to considerable ecological risk for almost the entire estuary, associated mainly with acid mine drainage from the nearby Iberian Pyrite Belt. In addition, the indices highlight several zones of extremely high risk, which are related to industrial and urban dumps in the vicinity of the estuary and to heavy traffic on the international bridge.

El objetivo general de la Tesis Doctoral es determinar la calidad ambiental de las aguas, suelos y sedimentos del Estero, y generar nuevos conocimientos sobre los factores que gobiernan el enriquecimiento, fraccionamiento geoquímico, movilidad y destino ambiental de elementos traza potencialmente tóxicos en los humedales costeros.Los objetivos concretos que se pretenden cubrir con esta investigación se resumen en los siguientes puntos:1. Identificar las fuentes difusas y los principales focos puntuales de contaminación por elementos traza.2. Determinar la composición, propiedades y parámetros indicadores de calidad ambiental de las aguas, suelos y sedimentos.3. Establecer el modelo de fraccionamiento de los elementos traza entre las distintas fracciones geoquímicas y especies mineralógicas de los suelos y sedimentos, siguiendo un esquema optimizado de extracción secuencial.4. Predecir el posible destino ambiental ante diferentes escenarios hipotéticos (oxidación, reducción, acidificación) y determinar la especiación química en medio acuoso de los elementos traza más lábiles.5. Cuantificar la fracción móvil y potencialmente móvil de los elementos traza y discutir su posible destino o transferencia a otros medios más sensibles.6. Proponer medidas correctoras para atenuar los efectos de la contaminación en las zonas más vulnerables.

This study relates elemental content of a range of edible crops grown in soils severely polluted by metals and metalloids as affected by traditional smallholder management practices. Five agricultural plots close to a sulfidic waste dump were monitored. Soil analysis demonstrated elevated concentrations of As, Cu, Pb and Zn that were greatly in excess of maximum statutory limits for agricultural soils in the studied region. The main vegetables (lettuce, chard, onion, potatoes) and lemon, together with their associated soils, were measured for elemental content. Extractable soil element concentrations were very low. There were differences in elemental accumulation between crops, but none exceeded statutory concentrations in edible parts. Soil-plant transfer factors were uniformly low for all elements and crops. It is concluded that traditional soil management practices (annual liming and application of animal manures) have created conditions for sustainable long-term safety use, with potential for multiple end-use, of these highly polluted soils.

This study relates elemental content of a range of edible crops grown in soils severely polluted by metals and metalloids as affected by traditional smallholder management practices. Five agricultural plots close to a sulfidic waste dump were monitored. Soil analysis demonstrated elevated concentrations of As, Cu, Pb and Zn that were greatly in excess of maximum statutory limits for agricultural soils in the studied region. The main vegetables (lettuce, chard, onion, potatoes) and lemon, together with their associated soils, were measured for elemental content. Extractable soil element concentrations were very low. There were differences in elemental accumulation between crops, but none exceeded statutory concentrations in edible parts. Soil-plant transfer factors were uniformly low for all elements and crops. It is concluded that traditional soil management practices (annual liming and application of animal manures) have created conditions for sustainable long-term safety use, with potential for multiple end-use, of these highly polluted soils.

Major ions, nutrients, trace elements and pesticides distribution were studied in a coastal wetland heavily impacted by human development in Spain. Past land use has altered the local hydrodynamics leading to the partitioning of the ecosystem into a tideland subject to marine influence, and an artificial freshwater reservoir created by stream impoundment. The tideland stretch is flooded twice a day with a heavy metal plume that emerges from the mine-polluted estuary of Huelva and propagates landward depicting the same dispersal trend of major seawater ions. Additionally, the tidal channel receives acid discharges from industrial point sources that contribute to metal enhancement. The impounded area and stream tributaries are affected by agrochemicals runoff (nitrate, phosphate, pendimethalin, simazine, diuron and therbuthylazine) from surrounding agricultural lands. The tidal regime plays a crucial role in the transport and dispersion of pollutants, except in the artificial reservoir where freshwater exhibits a seasonal mineralization pattern.